The Morphometrical Variance and Abundance Of

The Pennsylvania State University

The Graduate School

College of Agricultural Sciences

REVIEW OF THE GENUS DIPLOTAXODON WITH A DESCRIPTION

OF TWO NEW SPECIES

A Thesis in

Wildlife and Fisheries Science

Titus Bandulo Phiri

Submitted in Partial Fulfillment of the Requirements for the Degree of

Master of Science

December 2013

The thesis of Titus Bandulo Phiri was reviewed and approved* by the following:

Jay R. Stauffer, Jr. Distinguished Professor of Ichthyology Thesis Adviser

Walter Tzilkowski Associate Professor Emeritus of Wildlife

Wilson Lazaro Jere Senior Lecturer of Fish Genetics

Jeremy Likongwe Associate Professor of Fisheries Sciences

Michael G. Massina Head and Professor Department of Ecosystems Science and Management

*Signatures are on file in the Graduate School

ABSTRACT

A review of the described species of the genus Diplotaxodon Trewavas 1935, deep water

(offshore) fishes endemic to Lake Malaŵi, was conducted and included the description of two new species. Diplotaxodon spp. represent another example of the rapid radiation of the

Haplochromine species in Lake Malaŵi. Fishes were collected from Domira Bay and Senga

Bay. Morphometric and meristic differences among spp. were analyzed using Sheared

Principal Component Analysis (SPCA) for the morphometric data and Principal Component

Analysis (PCA) for the meristic data. To date seven species of Diplotaxodon are formally described. The investigations from this study resulted into describing two new species which were known by cheironym.

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TABLE OF CONTENTS

LIST OF FIGURES ...... vi LIST OF TABLES ...... ix AKNOWLEDGEMENTS ...... xi

CHAPTER 1 ...... 1 1.0.0 GENERAL INTRODUCTION ...... 1 1.1.0 Study area ...... 2 1.2.0 Study goals and objectives ...... 5 2.0.0 GENERAL METHODOLOGY ...... 7 2.2.0 Collection of Fish Specimen...... 7 2.3.0. Data collection (Meristic and Morphometric) ...... 7 2.4.0 Meristic data ...... 10 2.5.0 Data analysis ...... 14 3.0.0 OVERVIEW OF THE GENUS Diplotaxodon TREWAVAS 1935 ...... 14 3.1.0 General Distribution of Diplotaxodon...... 15 4.0.0 DESCRIBED SPECIES ...... 15 4.1.0 Diplotaxodon apogon Turner & Stauffer, 1998 ...... 15 4.2.0. Diplotaxodon ecclesi Burgess & Axelrod, 1973 ...... 19 4.3.0 Diplotaxodon macrops Turner & Stauffer, 1998 ...... 20 4.4.0 Diplotaxodon aeneus Turner & Stauffer, 1998 ...... 22 4.5.0 Diplotaxodon limnothrissa Turner, 1994 ...... 26 4.6.0 Diplotaxodon greenwoodi Stauffer &McKaye, 1986...... 32 4.7.0 Diplotaxodon argenteus Trewavas, 1935 ...... 38 5.0.0. Overview of undescribed species...... 45 CHAPTER 2 ...... 47

6.0.0 DESCRIPTION OF TWO NEW SPECIES ...... 47 6.1.0. INTRODUCTION ...... 47 7.0.0 New species of Diplotaxodon ...... 50 Diplotaxodon altus n. sp., n. nov (nova species, novem nomen) (Fig. 18)...... 50 Diplotaxodon sp. ‘deep’...... 50 7.1.0 Results ...... 52

8.0.0 Diplotaxodon maxillalongus n. sp., n. nov (nova species, novem nomen) (Fig. 18) ...... 67 Diplotaxodon sp. ‘maxillalongus’...... 67 8.1.0 Results ...... 70 9.0.0 Discussion ...... 83 10.0.0 Conclusion ...... 86

CHAPTER 3 ...... 88 11.0.0 Dichotomous key for Diplotaxodon ...... 88 13.0.0 Remarks...... 92 LITERATURE CITED ...... 93

LIST OF FIGURES

Figure 1: Maps illustrating location of the study area, Lake Malaŵi showing Domira Bay and Senga Bay in Salima District. Inset is map of Africa showing The Great Lift Valley Lakes and location of Lake Malaŵi. (Source: Google earth and http://www.odci.gov/cia/publications) ..... 4 Figure 2: Diplotaxodon spp. showing landmarks and distances measured as indicated by the numbered landmarks, the measured points not shown in the figure include orbital depth, cheek depth, horizontal and vertical eye diameter...... 8 Figure 3: Illustration of counting of main external meristic sets of variables on dorsal spines, dorsal rays, anal spines, anal rays and lateral line scales in black dots...... 10 Figure 4: Counting model for rays on pectoral-fin and pelvic-fin as part of the meristic variables. .... 11 Figure 5: Format for counting scales on the cheek, scales appear to form a pattern/ series were considered as indicated by I, II, and III representing 3 series of scales ...... 12 Figure 6: Part of the gill bar arch from the right hand side indicating how the gill rakers were counted for epibranchial and ceratobranchial...... 12 Figure 7: Diplotaxodon apogon, holotype from British Museum, described by Turner and Stauffer in (1998). Holotype: BMNH 1996.4.30:21a ripe male of 87.8mm standard length (Source: Turner and Stauffer 1998)...... 17 Figure 8: Plots of the sheared second principle components (morphological data) and the first factor score, first principle component (meristic data) for Diplotaxodon apogon and Diplotaxodon limnothrissa sampled from commercial vessel in Domira Bay, Lake Malawi in 2012 ...... 18 Figure 9: Diplotaxodon ecclesi described from a male holotype: USNM 210696 of 145.7mm standard length, collected off Monkey Bay by Herbert R. Axelrod in 1973, redefined by Turner & Stauffer 1998. Photo by Dr. Herbert R. Axelrod (Source://fishbase.org)...... 20 Figure 10: Diplotaxodon macrops, described from a ripe male holotype: BMNH 1996.4.30:1, with 106.7mm in standard length and was collected from 100m depth off Monkey Bay at 14o03′S 34o56′E by Turner in 1991. (Source: //wikipedia.org)...... 22 Figure 11: Diplotaxodon aeneus, described from a ripe male of 125mm standard length, holotype: BMNH 1996.4.30:16, collected from a depth of 400m northeast of Nkhata Bay by ODA/SADC pelagic Resource Project between 30 November 1993-December 1994 (source: Turner and Stauffer 1998)...... 23 Figure 12: Freshly caught D aeneus (Photo: Martin J.Genner) ...... 24 Figure 13: Male Diplotaxodon limnothrissa, at the beginning to develop breeding dress, Holotype collected in 1991 is in the British Museum (Source:http://www.fishbase.org)...... 27 Figure 14: Plots of the sheared second principle components (morphological data) and the first factor score, first principle component (meristic data) for Diplotaxodon greenwoodi and Diplotaxodon limnothrissa sampled from commercial vessel in Domira Bay, Lake Malaŵi in 2012 ...... 31 Figure 15: Diplotaxodon greenwoodi specimen from Pennsylvania State University fish Museum (Photo: Ad Connings)...... 33

Figure 16: Plots of the sheared second principle components (morphological data) and the first factor score, first principle component (meristic data) for Diplotaxodon apogon and Diplotaxodon greenwoodi sampled from commercial vessel in Domira Bay, Lake Malaŵi in 2012...... 37 Figure 17: Diplotaxodon argenteus, a benthopelagic fish species; (Photo source: malawicichlids.com) ...... 39 Figure 18: Plots of the sheared second principle components (morphological data) and the first factor score, first principle component (meristic data) for Diplotaxodon argenteus and Diplotaxodon limnothrissa sampled from commercial vessel in Domira Bay, Lake Malaŵi in 2012 ...... 44 Figure 19: A fin clipped female Diplotaxodon altus from collected from Senga Bay, northeast of Chipoka, Lake Malawi. (Photo: by Evance Samikwa 2013)...... 51 Figure 20: Plots of the sheared second principle components (morphological data) and the first factor score, first principle component (meristic data) for Diplotaxodon apogon and Diplotaxodon altus sampled in Senga Bay and Domira Bay, Lake Malaŵi in 2012-2013 ...... 56 Figure 21: Plots of the sheared second principle components (morphological data) and the first factor score, first principle component (meristic data) for Diplotaxodon argenteus and Diplotaxodon altus...... 59 Figure 22: Plots of the sheared second principle components (morphological data) and the first factor score, first principle component (meristic data) for Diplotaxodon maxillalongus and Diplotaxodon altus...... 62 Figure 23: Plots of the sheared second principle components (morphological data) and the first factor score, first principle component (meristic data) for Diplotaxodon altus and Diplotaxodon greenwoodi...... 65 Figure 24: Plots of the sheared second principle components (morphological data) and the first factor score, first principle component (meristic data) for Diplotaxodon altus and Diplotaxodon limnothrissa ...... 66 Figure 25: A female Diplotaxodon maxillalongus from collected from Senga Bay, northeast of Chipoka. (Photo: by Evance Samikwa 2013)...... 69 Figure 26: Part of the mouth showing the jaw arrangement and the teeth structure on the lower jaw . 69 Figure 27: Plots of the sheared second principle components (morphological data) and the first factor score, first principle component (meristic data) for Diplotaxodon argenteus and Diplotaxodon maxillalongus...... 72 Figure 28: Plots of the sheared second principle components (morphological data) and the first factor score, first principle component (meristic data) for Diplotaxodon maxillalongus and Diplotaxodon greenwoodi...... 75 Figure 29: Plots of the sheared second principle components (morphological data) and the first factor score, first principle component (meristic data) for Diplotaxodon maxillalongus and Diplotaxodon limnothrissa...... 78 Figure 30: Plots of the sheared second principle components (morphological data) and the first factor score, first principle component (meristic data) for Diplotaxodon apogon and Diplotaxodon maxillalongus...... 81

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Figure 31: Diplotaxodon spp. with a juvenile fish in the mouth...... 92

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LIST OF TABLES

Table 1: Morphometric measurements as a straight line joining two distinct points, 1-15 are related to the standard length and the 16-23 are related to the head length, the measurements were used for the sheared principal components analysis ...... 9 Table 2: Main meristic variable and codes used to collect and enter data, counting follows the order in the table...... 13 Table 3: Morphometrics of Diplotaxodon macrops (holotype and 19 paratypes), D. apogon (holotype and 20 paratypes), D. aeneus (holotype and 5 paratypes), and D. ecclesi (holotype) (source:Ichthyol. Explor. Freshwaters, vol.8 no. 3, pp. 239-252, 1998) ...... 25 Table 4: Morphometric and meristic values of type series of Diplotaxodon limnothrissa (n= 23) with mean, standard deviation and range of the population sampled from commercial vessel at Domira Bay in 2012 ...... 27 Table 5: The Sheared principal components (PC2) and Unsheared Principle component (PC2) variable loadings on size for D. greenwoodi and D. limnothrissa ...... 29 Table 6: The principle component analysis PC1 (meristic) and their standardized scoring coefficients for D. greenwoodi and D. limnothrissa ...... 30 Table 7: Principal morphometric and meristic characteristics of Diplotaxodon greenwoodi (n=4 and includes holotype). (Source: Proceedings of Biological Society of Washington 99(1), 1986, pp. 29-33) ...... 34 Table 8: The Sheared principal components (PC2) and Unsheared Principle component (PC2) variable loadings on size for D. greenwoodi and D. apogon...... 35 Table 9: The Principle Component Analysis PC1 (meristic) and their standardized scoring coefficients for D. greenwoodi and D. apogon ...... 36 Table 10: Morphometric and meristic values of type series of Diplotaxodon argenteus (n= 11) with mean, standard deviation and range of the population including the holotye sampled from commercial vessel at Domira Bay in 2012-2013 ...... 39 Table 11: The Sheared principal components (PC2) and Unsheared Principle component (PC2) variable loadings on size for D. argenteus and D. limnothrissa...... 41 Table 12: The principle component analysis PC1 (meristic) variables and their standardized scoring coefficients for D. argenteus and D. limnothrissa ...... 42 Table 13: List of possible existing but undescribed species in the genus Diplotaxodon and their taxonomic status ...... 45 Table 14: Morphometric and meristic values of type series of Diplotaxodon altus (n= 18) with mean, standard deviation and range of the population including the holotype sampled from Senga Bay and Domira Bay in 2012-2013 ...... 52 Table 15: The Sheared principal components (PC2) and Unsheared Principle component (PC2) variable loadings on size for D. altus and D. apogon...... 54 Table 16: The principle component analysis PC1 (meristic) and their standardized scoring coefficients for D. altus and D. apogon ...... 55

Table 17: The Sheared principal components (PC2) and Unsheared Principle component (PC2) variable loadings on size for D. altus and D. agenteus...... 57 Table 18: The principle component analysis PC1 (meristic) variables and their standardized scoring coefficients for D. altus and D. argenteus ...... 58 Table 19: The Sheared principal components (PC2) and Unsheared Principle component (PC2) variable loadings on size for D. altus and D. maxillalongus...... 60 Table 20: The principle component analysis PC1 (meristic) variables and their standardized scoring coefficients for D. altus and D. maxillalongus ...... 61 Table 21: The Sheared principal components (PC2) and Unsheared Principle component (PC2) variable loadings on size for D. altus and D. greenwoodi...... 63 Table 22: The principle component analysis PC1 (meristic) variables and their standardized scoring coefficients for D. altus and D. greenwoodi ...... 64 Table 23: Morphometric and meristic values of type series of Diplotaxodon maxillalongus (n= 18) with mean, standard deviation and range of the population including the holotye sampled from Senga Bay and Domira Bay in 2012-2013 ...... 70 Table 24: The Sheared principal components (PC2) and Unsheared Principle component (PC2) variable loadings on size for D. maxillalongus and D. greenwoodi ...... 72 Table 25: The principle component analysis PC1 (meristic) variables and their standardized scoring coefficients for D. maxillalongus and D. apogon ...... 74 Table 26: The principle component analysis PC1 (meristic) and their standardized scoring coefficients for D. maxillalongus and D. limnothrissa ...... 76 Table 27: The principle component analysis PC1 (meristic) variables and their standardized scoring coefficients for D. maxillalongus and D. limnothrissa ...... 77 Table 28: The Sheared principal components (PC2) and Unsheared Principle component (PC2) variable loadings on size for D. maxillalongus and D. apogon ...... 79 Table 29: The principle component analysis PC1 (meristic) variables and their standardized scoring coefficients for D. maxillalongus and D. apogon...... 80 Table 30: The adopted scientific classification (Linnaeus hierarchy) to which Diplotaxodon spp. were described for the binomial nomenclature...... 91

AKNOWLEDGEMENTS

I would like to convey my sincere appreciations to USAID-Malaŵi and the management of USAID Initiative for Long-term Training and Capacity Building

(UILTCB) for the financial assistance to pursue this study. I would also like to specifically thank Mywish Maredia, UILTCB Program Co-Director, Vincent

Langdon-Morris and Jean Msosa-Maganga of USAID-Malawi and Irv Widders,

Director of Dry Grain Pulses for their support and guidance in processing and implementing my scholarship. I am also very thankful to the Office of International

Program at College of Agriculture of Penn State University for steadily processing finances and guidance throughout my study program. Many thanks should go to

Melanie Gilbert and Thom Gill for all the support in coordinating the scholarship and for the administrative work during my stay at the Great University.

With great honor and humbleness, I would like to express my deeper most profound appreciation to Dr. Jay Stauffer, Distinguished Professor of Ichthyology, my academic supervisor and Director of Graduate Studies for Ecosystem Science and

Management of the Pennsylvania State University (USA) for the marvelous supervisory work and total guidance in my academic work, research and writing of the thesis. Your supervision, advice, critiques and foresight inclusive planning towards my academic studies and research made my MSc. program the most educating and memorable in my lifetime. I also thank Dr. Walter Tzilkowski,

Associate Professor Emeritus of Wildlife of The Pennsylvania State University (USA) for your patience to see my work done having retired from active professorship. I am very grateful to my Co-supervisor Dr. Wilson Jere for putting me in track during my research, I enjoyed every moment of our interaction. Many thanks should go to Dr.

Jeremy Likongwe for accepting to be in my committee.

I am indebted to Emily Hill for being an excellent administrator for my graduate studies, you were always ready to help and see to it that all is done in time.

You were almost a mother, I salute you and I cherish your endless jovial mood.

Similarly, I would like to thank, most sincerely Bobbi Jo Scovern, Barb Irwin,

Christin and other administrators for their indispensable support, without you my study program could not have been accomplished.

I am also grateful to Ministry of Agriculture and Food Security through The

Department of Fisheries for proving me with supporting documents, financial assistance and more importantly offering me a two year study leave. I would like to specifically thank Jacquiline Kazembe, Training Coordinator in the Department of

Fisheries for the prompt support and encouragements throughout the study program.

I would like to express my most reflective appreciation to my wife Julliet

Jinazali Phiri and my intelligent daughter Lusungu Phiri for their endless love, endurance, encouragements, moral and spiritual support. Your patience gave me hope and made me get focused on my studies. I thank my ‗Mama‘ Love Chirwa, for all the support while I was away. I would like to thank all my relatives for material and moral support to my family while I was away.

I would like to thank my systematics lab mates Shelly Pickett, for sourcing

Diplotaxodon samples from Penn State Fish Museum, Shan Li, Bill Hanson, David

Ryan, Rich Taylor, Casey Weathers, Karl Werner and many others for all the assistance, encouragements and moral support throughout my study period.

I am very thankful to the American Museum of Natural History and British

Natural History Museum for the type specimen. I would like to thank Tim Stecko for the scanned images of Diplotaxodon specimen.

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I also thank Mr M. Ngochera, Officer in Charge -Senga Bay Fisheries

Research Centre for the logistic support and other official arrangements made during the study. I thank all members of staff for the Centre for various forms of work that contributed greatly towards this study. Lastly I thank General management of

Maldeco Fisheries Ltd (Salima) for allowing me to collect fish samples from catches of fish Eagle vessel.

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DEDICATION

―Take up one idea. Make that one idea your life - think of it, dream of it and live on that idea. Let the brain, muscles, nerves, every part of your body, be full of that idea, and just leave every other idea alone. This is the way to success‖

~Swami Vivekananda~

I dedicate this work to my Daughters Lusungu and Luskani. I say ―be focused, stick to your dreams; you shall be successful.‖

I also dedicate this work in memory of my Grandfather and also a friend, the late Hezron Chimpetewu Phiri who passed on (2012) while I was in USA for studies. I wish I said ―good bye‖. I will always remember you through strings of stories of endurance, patience and history of our clan. YOU were an inspiration to me.

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CHAPTER 1

1.0.0 GENERAL INTRODUCTION

Cichlid fishes are known to be the species rich and diverse group of vertebrates.

The African freshwaters are considered to contain between 70 and 80% of all the described cichlid fishes (Stauffer et al. 2007). The Haplochromine of the East African

Great Lakes are considered a classic example of adaptive radiation (Stauffer et al.

2007, Joyce et al. 2011, Kerschbaumer and Sturmbauer 2011). An extraordinary number of cichlid fishes are considered an evolutionary mystery (Yong-Jin et al.

2011), and the largest species radiation is from Lake Malaŵi, estimated to contain as many as 850 endemic species ( Konings 2007, Joyce 2010). It is this rapid radiation of cichlids in the Great Lakes of East Africa that has attracted the most attention and almost 2000 species of cichlids have evolved in the very recent evolutionary past

(Kocher 2004). Koning (1995) stated that no lake in the world contains such a diversified and distinct community of cichlid fishes as Lake Malaŵi. The driving mechanism for these speciation events is not known (Stauffer et al. 2007) and the understanding of the evolutionary origins of these radiations has been limited by inadequate taxonomic and genomic sampling (Shaw 2000, Meyer 1990 and Joyce

2010). Such a rapid radiation of species is a significant challenge for phylogenetic reconstruction (Kocher 2004). Nevertheless, the lack of morphological differentiation, the absence of sympatry, and the inability of allozyme data to delimit species do not diminish the validity of the species status of many of these populations (Stauffer,

2001.). The most significant finding reported is the extent to which Diplotaxodon species have adapted to the pelagic mode of life (Thompson et al. 1996).

There are a number of concepts that try to explain the cause of this rapid species radiation of endemic cichlid species of Lake Malaŵi. Genner et al. (2010) recognizes

that there was a period of isolation and divergence of populations in satellite lakes within the current Lake Malaŵi basin, due to climate-driven changes in the volume of the lake. Genner et al. (2010), however argued that it is very difficult to imagine a deep water species such as Diplotaxodon being separated by physical barriers.

Nevertheless, Genner et al. (2010) did not ignore the behavioral traits like reproductive seasonality where isolation of gene pools can take place within the lake.

Various authorities have proposed various models of species recognition based on various speciation concepts. Practically, Kocher (2004) recommends morphological species concept in which individuals are categorized by similarities in size, shape and color. Kocher (2004) further said that organisms present at a particular location are usually sorted by color pattern and/or morphology into discrete groups that all would agree to be unique species. Cichlids are not an exception and most species are usually distinguished using morphometric and breeding color. For instance in describing the three deep water cichlids, Turner and Stauffer (1998) distinguished Diplotaxodon aeneus by male breeding color and morphometric information. The distinctive male colors and morphology of Diplotaxodon apogon and Diplotaxodon aeneus are convincing evidence that these are separate species (Turner and Stauffer, 1998). Four sympatric putative species collected from deep water gill nets, were diagnosed on the basis of male breeding pattern (Genner 2006).

1.1.0 Study area

Lake Malaŵi is bordered by Malaŵi, Mozambique, and Tanzania and lies between 90 30″S and 14030″S. It is approximately 550km long and an average width of 55km. Lake Malaŵi has surface area of 28,800km2 with maximum depth of over

700m and average depth of 292m (Thompson, 1996). The lake is the ninth largest in the world by area and the surface lies 472 meters above sea level (Konings 1995).

Domira Bay is located in the southern part of Lake Malaŵi and is located at13034″600S and 34027″0E (Fig. 1). The Bay is about 40 km wide and faces northeast. The Bay has a wide shelf of relatively shallow water with the 50m contour about 10km offshore and 100m contour 20km out. The area around Mbenji Island in particular is an important fishing ground (Tweddle 1994). Mbenji Island is situated at the middle of Domira Bay, 15km from the main land (Chikombe beach) in Salima

District. The Island is well known for its traditional fishery management scheme in regulating fishing. Fishing in the vicinity of the Island is subjected to closed season between December and March.

Senga Bay is also found in south western part of Lake Malaŵi and is located at an elevation of 472 meters above sea level. Its coordinates are 13°45'0" N and

34°37'0" (Fig. 1). The area has a large number of fishers and is an important fish market. The area is known for fishing at night and use light to attract fish.

Domira Bay Senga Bay

Figure 1: Maps illustrating location of the study area, Lake Malaŵi showing Domira

Bay and Senga Bay in Salima District. Inset is map of Africa showing The Great Lift

Valley Lakes and location of Lake Malaŵi. (Source: Google earth and http://www.odci.gov/cia/publications)

1.2.0 Study goals and objectives

Turner (1996) stated that Diplotaxodon fishes are of scientific interest because most theories of vertebrate speciation assume that population have to be separated geographically; however, it is a greater challenge to explain how these fishes have radiated into so many species. Turner (1996) further emphasized that among the fishes of Lake Malaŵi, the offshore cichlids are (i) the most important for human food, (ii) the most interesting to evolutionary biologists, (iii) the species most likely to be in danger of extinction, and (iv) is one of the least known. Stauffer et al. (2007) explained that fish throughout the world are threatened by overfishing, the introduction of exotic species, habitat destruction, and anthropogenically induced environmental stress. Stauffer et al. (2007) further stated that determination of the specific status of local taxonomic units is critical for the development of programs that conserve fish for purpose of food, aquaculture, tourism, disease control, and scientific investigation.

The fisheries in Lake Malaŵi shifted from shallow waters (<30m) to off-shore to catch species such as Diplotaxodon because shallow water fishery was overexploited. Thompson et al (1996) indicated that cichlids comprised approximately 88% of the offshore fish biomass of which 71% of the biomass was

Diplotaxodon spp. Turner (1996) recognized Diplotaxodon to account for a larger proportion of biomass in Lake Malaŵi than any other genus. At this time, however there is no evidence that Diplotaxodon species can indefinitely support such a fishery.

The introduction of commercial fishery to some parts of central region lake shore district of Malaŵi attracted a need for scientific information of this resource. These fishes mainly occur in the mid-water trawl catches as well as the catches of deep

water bottom trawls. The fishes also occurred in catches of pair trawls and chilimira nets, a huge locally fabricated fishing gear (Kasembe 2006).

Commercial fishery has for a long time been operating in the south-east arm and Diplotaxodon spp. were the main catch. Most of the studies conducted on the

Diplotaxodon were concentrated in the southeast and southwest arms of Lake Malaŵi.

A scientific study of Diplotaxodon spp in other parts surrounding southern part of

Lake Malaŵi provided information needed to understand the long term population diversity, population structure, and the evolutionary biology for the management of the fish in this genus.

There was a need to establish how many of the undescribed Diplotaxodon spp. existed around Salima. There was a threat that some of the described species or undescribed Diplotaxodon species which are found in the area could have been extirpated before management strategies were implemented. This study covered the information gap of the Diplotaxodon species found in areas around Salima District.

Species in the genus Diplotaxodon found in Salima District were investigated and the information can be incorporated in the management strategies for these species, which are mainly targeted by commercial and semi commercial fishery. The study areas are some of the most active and important fishing Districts of the lakeshore areas in Malaŵi. The fishers‘ routine sorting and record keeping of small- sized fishes such as Diplotaxodon, has never been based on species specific data, of which detailed information retrieval had been difficult or impossible. Detailed scientific information on Diplotaxodon from the commercial and semi commercial fishery is important for resource management and reference.

2.0.0 GENERAL METHODOLOGY

2.1.0 Material examined

Type series examined were borrowed from National Museum of Natural

History, Diplotaxodon greenwoodi (Holotype: USNM 270847) and Diplotaxodon ecclessi (Holotype: USNM 210696). British Museum of Natural History (BMNH),

Diplotaxodon apogon (Holotype: BMNH 1996.4.30:21). Diplotaxodon limnothrissa

(Holotype: BMNH 1992.3.25.1). Penn State University Fish Museum, Diplotaxodon macrops (Paratype: PSU 3024).The results obtained from the type series were used in delimitation between new species description and existing described species.

2.2.0 Collection of Fish Specimen

Adult Diplotaxodon fish were sampled from catches in commercial, semi commercial and small scale fishery every month for six months starting from August

2012 through January 2013 in Domira Bay and Senga Bay. The small scale fishers were very restrictive to take any form anesthesia to sedate fish on board avoiding deep odor to contaminate other fish meant for sale. Fish were placed in cold water for small scale and rushed to the shore thereafter fish were transferred into water with clove oil immediately upon reaching the beach. While in commercial fishery targeted fish species were euthanized with clove oil. Fish were sorted by species with close pictorial book reference and photographed and put in a labeled 2000ml jar with ice.

Subsequently fixed with 10% formalin upon reaching the laboratory ice and. After five days the fish were rinsed for two weeks and preserved in 70 % ethanol.

2.3.0. Data collection (Meristic and Morphometric)

The morphometric data were collected using digital calipers with a computer chip that recorded the data directly into the computer using Excel. The morphometric data were measured to the nearest 0.01mm. Meristic data were collected

simultaneously for every specimen and entered into an Excel spread sheet. Some meristic data such as teeth, scales and rays were collected with the aid dissecting microscope.

Figure 2: Diplotaxodon spp. showing landmarks and distances measured as indicated by the numbered landmarks, the measured points not shown in the figure include orbital depth, cheek depth, horizontal and vertical eye diameter.

The morphometric and meristic data were taken from the left side as detailed by (Stauffer 1991.). All morphometric data were recorded to the nearest 0.01mm and all expressed as percent head length (HL) or percent standard length (SL.

Table 1: Morphometric measurements as a straight line joining two distinct points, 1-

15 are related to the standard length and the 16-23 are related to the head length, the measurements were used for the sheared principal components analysis

Number Morphometric measurements Code 1 Standard Length SL

2 Body Depth BD

3 Snout to Dorsal Fin Origin SDF

4 Snout to Pelvic Fin Origin SPF

5 Dorsal Fin Base Length DFBL

6 Anterior Dorsal Fin to Anterior Anal fin ADAA

7 Anterior Dorsal Fin to Posterior Anal fin ADPA

8 Posterior Dorsal Fin to Anterior Anal fin PDAA

9 Posterior Dorsal Fin to Posterior Anal fin PDPA

10 Posterior Dorsal Fin to Ventral origin Caudal Fin PDVC

11 Posterior Anal Fin to Dorsal Caudal Fin Origin PADC

12 Anterior Dorsal Fin to Pelvic Fin Origin ADPF

13 Posterior Dorsal Fin to Pelvic Fin Origin PDPF

14 Caudal Peduncle Length CPL

15 Least Caudal Peduncle Depth LCPD

16 Head Length HL

17 Head Depth HD

18 Horizontal Eye Diameter HED

19 Vertical eye Diameter VED

20 Pre-orbital Eye Diameter POED

21 Post Orbital Head length POHL

22 Cheek Depth CD

23 Lower Jaw Length LJL

2.4.0 Meristic data

The meristic data included counts of spines, rays, teeth, gill rakers and lateral line scales. The lateral line scales were counted along the upper lateral line and continued by counting the scales along the lower lateral line (Fig. 3). Overlapping scales were not counted. The meristic counts were done twice and averages were entered into Excel input sheet.

Figure 3: Illustration of counting of main external meristic sets of variables on dorsal spines, dorsal rays, anal spines, anal rays and lateral line scales in black dots.

The spines were identified by their hard construction, which was not segmented, unlike the rays (Fig. 4) which were soft and segmented. At least fourteen meristic variables were collected from all the samples. Contrast to all other counts the gill-rakers on ceratobranchial and the gill-rakers on epibranchial were counted from

the right hand side.

Figure 4: Counting model for rays on pectoral-fin and pelvic-fin as part of the meristic variables.

Rays (Fig. 4) were counted closer to the base to avoid counting branches.

Small ray at the end of fin was not counted as it has a combined a root with the big adjacent ray. Pelvic fin spine was not included as part of the meristic variable.

Scale rows were a series of scales that appeared to form a pattern. The cheek scale rows (Fig. 5) were considered from outermost scale pattern. In most cases the scale rows were irregular posterior dorsally but only those that made a logical row were considered.

Figure 5: Format for counting scales on the cheek, scales appear to form a pattern/ series were considered as indicated by I, II, and III representing 3 series of scales

Figure 6: Part of the gill bar arch from the right hand side indicating how the gill rakers were counted for epibranchial and ceratobranchial.

The gill rakers were counted on the outer arch; on the upper shorter part

(epibranchial) they were counted to where the bar starts forming an arch and the gill rakers on the ceratobranchial they were counted on the longer lower bar. The very middle gill raker separating the gill rakers on epibranchial and gill rakers on ceratobranchial was not counted (Fig. 6).

Table 2: Main meristic variable and codes used to collect and enter data, counting follows the order in the table.

No. Meristic variable Code 1 Doral Fin Spines DFS

2 Dorsal Fin Rays DFR

3 Anal Fin Spines AFS

4 Anal fin Rays AFR

5 Pelvic Fin Rays P2RAYS

6 Pectoral Fin Rays P1RAYS

7 Lateral Line Scales LLS

8 Pored Scales Past Lateral Line PSPLL

9 Scale Rows on the Cheek SRC

10 Gill rakers on ceratobranchial GRFC

11 Gill rakers on epibranchial GRFE

12 Teeth Outer Row of Left Lower Jaw TORLLJ

13 Teeth Rows on Upper jaw TRUJ

14 Teeth Rows on Lower jaw TRLJ

2.5.0 Data analysis

Morphometric data were analyzed using a sheared principal component analysis, which factors the covariance matrix and restricts size variation to the first principal component (Humphries et al. 1981, Bookstein et al. 1985). Meristic data were analyzed using a principal component analysis in which the correlation matrix was factored. Differences among species were illustrated by plotting the sheared second principal components (SPC2) of the morphometric data against the first principal components (PC1) of the meristic data (Stauffer & Hert 1992). Minimum polygon clusters were formed for each population. Institutional abbreviations follow Leviton et al. (1985).

If the minimum polygon plots overlapped, an ANOVA was used to determine if the minimum polygon clusters for the sheared principal component axis of the morphometric data and the first principal component axis of the meristic data to determine if the clusters were significantly different along one axis, independent of the other. If the mean multivariate scores of the clusters formed by the plots were significantly different along one axis independent of the other, a Duncan Multiple

Range Test (DMRT) (p<0.05) was used to determine the difference of clusters from each other. If the cluster were not significantly different along one axis independent of the other, a MANOVA was used to determine if the clusters were different in multivariate space.

3.0.0 OVERVIEW OF THE GENUS Diplotaxodon TREWAVAS 1935

The cichlid fishes of genus Diplotaxodon are mid-water zooplanktivores and piscivores endemic to Lake Malaŵi (Genner 2007). Turner (1996) defined

Diplotaxodon species to have upwardly-angled mouth and adult sizes ranges from 10-

30 cm, depending on the species. Generally the species in the genus Diplotaxodon can be distinguished from other species in having relatively large eyes. Turner (2001) recognized eleven species of the genus Diplotaxodon and, further stated that five of the eleven are not described.

Diplotaxodon was derived from a combination of three terms: ―diplo‖ means

―double rows‖ in this case ―double rows of teeth‖, ―taxi‖ means order or arrangements and ―odon‖ means teeth. In general, species in the genus Diplotaxodon have two rows of teeth. The common local name for Diplotaxodon is ―Ndunduma‖ and it is also called ―Jamison‖ in some southern parts of the lakeshore district areas.

3.1.0 General Distribution of Diplotaxodon

Diplotaxodon spp. are endemic to Lake Malaŵi and are widely distributed in the lake. Kanyere et al. (2005) noted that Diplotaxodon spp. are probably the most abundant cichlid in the lake with biomass estimates of around 87,000 metric tons in the pelagic zone alone. Thus, Diplotaxodon spp. comprise the most fish biomass in

Lake Malaŵi. The populations differ significantly within the lake and Kanyere et al.

(2005) indicated that D. limnothrissa was the most abundant in south east arm of the

Lake.

4.0.0 DESCRIBED SPECIES

4.1.0 Diplotaxodon apogon Turner & Stauffer, 1998

Type locality. Off Monkey Bay, Lake Malaŵi.

Diagnosis. Small size, not known to exceed 110mm in standard length. Head large ranges between 35.5-39.7% SL. Has relatively deeper body (Fig 7) range between 32-37 % SL and larger eye range between 30-36 % HL that distinguishes this species from most Diplotaxodon spp. Among the known species in the genus

Diplotaxodon, which have the eye diameter greater than the snout length, it is the only species in which the ripe males have pale silvery flanks. Lower jaw range between

42-46% HL, relatively longer than that of D. macrops ranged between 37-41% HL.

Body depth ranged between 32-37% SL and greater than D. ecclesi ranged between

32% SL. Dorsal spines range between 12-14 and gill rakers of ceratobranchial range between 16-20, lower than D. macrops ranges 14-16 and 20-25 respectively (Table 3).

Description. Morphometric ratios and meristic data in Table 3. Body laterally compressed. Dorsal head profile straight and 22o to horizontal. Premaxillary pedicel prominent and profile at 31o to horizontal axis. Gape at 53o to horizontal axis. Lower jaw slightly protruded and premaxillary with beak. Posterior end of maxilla behind nostril and just anterior to eye. Pectoral fin long to first anal spine. Pelvic fin short, not to vent. In mature males to anterior of genital papilla. Longest rays of dorsal and anal fins not to base of caudal fin. Lateral line with scales between 31-34. Teeth numerous, very small, slender and curved. Color generally silvery and counter-shaded grey dorsally and white ventrally.

Distribution. Commonly found in catches from trawl net from depth of 80-130m.

According to Turner & Stauffer (1998), D. apogon was described from the southern arm of the lake where it is abundant on the shelf area depths of 100m or more. The species also captured in samples from similar habitats in the South-West Arm, Senga

Bay, Domira Bay and off Nkhotakota in the south-western part of the lake, off

Metangula on the eastern shore, and in Weissmann Bay in the far north (Turner et al.2007).The species was also sampled from other areas of Lake Malaŵi.

Etymology. The specific name refers to the general similarity of body form to some of the cardinal fishes of the genus Apogon La Cepède.

Figure 7: Diplotaxodon apogon, holotype from British Museum, described by Turner and Stauffer in (1998). Holotype: BMNH 1996.4.30:21a ripe male of 87.8mm standard length (Source: Turner and Stauffer 1998).

Specific morphometric and meristic counts are provided in Table 3. All measurements and counts were based holotype: BMNH 1996.4.30:21and 9 recently collected specimen. It morphologically resembles D. limnothrissa (Fig 13); however the minimum polygons when the sheared second principal components of the

morphometric data were plotted against the first principal components of the meristic data were significantly (p<0.05) different along the meristic axis (Fig. 8).

0.20 D. apogon

D. limnothrissa )

a 0.15

a c

i 0.10

e m

o 0.05

m (

0.00

D -0.05

H S -0.10

-2 -1 0 1 2 3 PC1 (meristic data)

Figure 8: Plots of the sheared second principle components (morphological data) and the first factor score, first principle component (meristic data) for Diplotaxodon apogon and Diplotaxodon limnothrissa sampled from commercial vessel in Domira

Bay, Lake Malawi in 2012

4.2.0. Diplotaxodon ecclesi Burgess & Axelrod, 1973

Type locality.Monkey Bay, Southeast arm Lake Malaŵi.

Redescription of D. ecclesi – Turner and Stauffer1998

Diagnosis. The eye diameter (32.9% HL) greater than snout length (31.3%

HL). Slender body (fig 9) with maximum depth of 32% of SL; caudal peduncle depth

11% of SL. Male bleeding color, dark grey or black with a white dorsal-fin margin that distinguishes it from D. aeneus and D. apogon. The lower jaw which is 42% of the head length is longer than that of D. macrops which ranges between 37%-41. D. ecclesi differs from D. argenteus in lesser number of scales in a lateral line in a series of 32-33 than 34-36 respectively. Distinguishes from D. limnothrissa, D. greenwoodi and D. argenteus by its relatively slender body at a maximum depth 32 % of standard length (Table 3).

Description. Morphometric ratios and meristic data in Table 3. Body less deep

(31.6% SL) or laterally compressed (14.4% SL) than congeneric species. Dorsal head profile straight and 21o to horizontal. Premaxillary pedicel prominent and profile at

23o to horizontal axis. Gape at 58o to horizontal axis. Premaxillary with small beak.

Pectoral fin not to first anal spine. Pelvic fin not to vent. Longest rays of dorsal and anal fins not to base of caudal fin. Lateral-line scales 32 and cheek scales in two rows.

Epibranchial with 6 gill rakers on outer arch; 22 gill rakers on outer arch of ceratobranchial. Teeth small, crowded, and erect. Gold/brown with black pelvic fins and white border on dorsal fin. Pelvic fin back with two yellow egg spots on anal fin.

Distribution. It was described from a single specimen collected at a depth of

90m off the Nankumba Penninsula, at the north of SE Arm. Individuals with similar morphology were collected from 60m at Domira Bay and 68m near Maleri Island

(Turner 1996). Turner and Stauffer (1998) noted that D. apogon was abundant from

depths of 80m to at least 130m in the southern part of Lake Malawi. The species was also sampled by Turner et al. (2001) in similar habitats in Senga Bay, Domira Bay and off Nkhota Kota in the south western part of the Lake, the eastern shore off

Metangula, and far north in Weissman Bay.

Etymology. Named after Dr. David H. Eccles, whose work helped to clarify the taxonomic confusion in the Lake Malaŵi cichlids.

Figure 9: Diplotaxodon ecclesi described from a male holotype: USNM 210696 of

145.7mm standard length, collected off Monkey Bay by Herbert R. Axelrod in 1973, redefined by Turner & Stauffer 1998. Photo by Dr. Herbert R. Axelrod

(Source://fishbase.org).

4.3.0 Diplotaxodon macrops Turner & Stauffer, 1998

Type locality. Monkey Bay, Southeast arm Lake Malawi.

Diagnosis. Small sized species (Fig 10) not known to exceed 120mm SL.

Distinguishes from D. argenteus, and D. limnothrissa by longer eye diameter than the snout (32.9% HL, 31.5% HL versus 24-33% HL, 30-38 HL and 25-29% HL, 32-40%

HL). Deep body ranges between 33.5-37% SL than D. ecclesi (31.5 % SL). Lower

jaw shorter ranges between 37-41% HL than that D. apogon ranges between 42-46%

HL. Higher number of ceratobranchial gill rakers and lateral-line scales than D. apogon (20-25 versus 16-20 and 33-35 versus 31-34) (see Table 3). Predorsal length ranges between 36-38% HL. Body depth ranges between 40-51% SL shorter and narrower than D. aeneus (38-40% and 40-42% respectively). Smaller head than D. aeneus (36-39% versus 46-51%).

Description. Morphometric ratios and meristic data in Table 3. Deep body laterally compressed. Dorsal head profile straight and 26o to horizontal. Premaxillary pedicel prominent and profile at 30o to horizontal axis. Gape at 57o to horizontal axis.

Premaxillary with small beak. Pectoral fin long, to just past first anal-fin spine. Pelvic fin of female short, not to vent and in males longer, to posterior to vent but rarely to first anal-fin spine. Longest ray of anal fin and dorsal fin not to base of caudal fin.

Lateral line between 33-35 and lower lateral straight. Two rows of scales between upper and lower lateral lines. Cheek with 2-3 rows of scales. Gill rakers on outer arch of epibranchial between 6-8 and on outer arch of ceratobranchial 20-25. Teeth on both upper and lower jaws small in 2-3 rows. Anal and pelvic fins white, with 1-2 large pale yellow egg spots on anal fin.

Distribution. Found in depths between 80-130m with a few below 120m in south eastern part of Lake Malaŵi. The distribution range extends to as far as

Nkhotakota.

Etymology. Macrops derived from a Greek word and refers to the large eye.

Figure 10: Diplotaxodon macrops, described from a ripe male holotype: BMNH

1996.4.30:1, with 106.7mm in standard length and was collected from 100m depth off

Monkey Bay at 14o03′S 34o56′E by Turner in 1991. (Source: //wikipedia.org).

4.4.0 Diplotaxodon aeneus Turner & Stauffer, 1998

Type locality. Monkey Bay, Southeast arm Lake Malaŵi.

Diagnosis. Uniform male breeding color including the dorsal fin. Eye diameter longer than snout length (30.4-34.5% versus 27.8-29.9%), distinguishing from other known species. Longer head ranges 38-40 % SL. Pre-dorsal length greater 40-42 %

SL. Body wider ranges 46-51 % of maximum depth than D. macrops which are 34-

38, 36-39 and 40-46 respectively. Pectoral-fin length ranges between 34-38 % SL and lower jaw length ranges 38-43 % HL shorter than D. apogon, 35-41 and 42-46 respectively. Body depth ranges between 34-37 % SL, greater than D. ecclesi, 32%

(Table 3).

Description. Morphometric ratios and meristic data in Table 3. Laterally compressed body; head moderately concave in profile above eye (Fig 11 and 12).

Dorsal head profile straight and 22o to horizontal. Premaxillary pedicel prominent and profile at 31o to horizontal axis. Gape at 53o angle to horizontal axis. Lower jaw slightly protruding (Fig 11 and 12). Premaxillary with small beak. Pectoral fin long,

well past first anal-fin spine. Pelvic fin of female short, not to vent and in mature males longer, reaching genital papilla. Longest ray of anal fin and dorsal fin not to base of caudal fin. Lateral-line with 31-34 scales; lower lateral line short but straight.

Cheek with 3 rows of scales. Outer arch of epibranchia with 5-7 gill rakers and 16-20 on outer arch of ceratobranchial. Slender teeth, and curved, with two series on both upper and lower jaws. Sexually active male uniformly dark.

Distribution. It is known to be from Nkhata bay area, but also near 10o5ʹS

34o10ʹE which is just southeast of Karonga (far north of Lake Malaŵi). Genner et al.

(2009) collected some samples in Chilumba and Karonga in 2004. Diplotaxodon aeneus is found between 25–160 m depth and occurs in the central and northern parts of the lake where it is considered to be rare; it is also known at Domira Bay further south (Kasembe 2006).

Etymology. The name ‗aeneus‘ is derived from a Latin word which means bronze and this was to refer to the bronze color of ripe male fish.

Figure 11: Diplotaxodon aeneus, described from a ripe male of 125mm standard length, holotype: BMNH 1996.4.30:16, collected from a depth of 400m northeast of

Nkhata Bay by ODA/SADC pelagic Resource Project between 30 November 1993-

December 1994 (source: Turner and Stauffer 1998).

Figure 12: Freshly caught D aeneus (Photo: Martin J.Genner)

Table 3: Morphometrics of Diplotaxodon macrops (holotype and 19 paratypes), D. apogon (holotype and 20 paratypes), D. aeneus (holotype and 5 paratypes), and D. ecclesi (holotype) (source:Ichthyol. Explor. Freshwaters, vol.8 no. 3, pp. 239-252, 1998)

D. macrops D. apogon D. aeneus D. ecclesi Variable Holotype Mean ± SD Range Holotype Mean ± SD Range Holotype mean ± SD Range Holotype

Standard length 106.7 94.5 54.5-117 87.8 91.5 62.5-109 125.2 129.4 125.2-137.2 35.5

As percent of SL Head length 36.1 35.5 ± 0.9 33.9-37.6 37.2 37.6±0.9 35.5-39.7 40.5 39.4±0.9 38.5-40.6 35.5 maximum depth 35.2 35 ± 1.0 33.5-36.8 35.9 35.3±1.3 32.4-37.3 37.1 35.3±0.9 34.3-37.1 31.6 maximum width 14.6 15.1 ± 0.5 14.4-16.5 16.1 16.4±0.5 15.7-17.6 16.9 16.9±0.6 16.0-17.9 14.5 Pectoral fin length 33 33.4 ± 1.6 29.6-37.6 35.1 37.2±1.6 34.9-40.7 33.6 32.3±0.9 31.4-34.0 27.8 Pelvic fin length 26 25 ± 1.8 21.3-28.2 24.9 23.0±1.2 21.1-25.1 25.4 25.9±1.5 22.8-27.3 22.9 Dorsal fin base length 48.5 47.6 ± 1.3 45.1-51.4 43.7 44.2±0.9 42.9-45.6 43.2 44.6±1.2 43.2-46.3 48.3 Pre-dorsal length 37.6 37 ± 0.9 35.5-38.7 39.1 40.4±1.3 38.2-42.5 40.9 40.8±0.6 40.2-42.0 36.8 Pre-pelvic length 42.6 41.2 ± 1.2 38.4-43.6 43.6 42.8±1.0 41.1-45.0 44.2 43.1±1.2 41.1-44.7 39.4

Caudal peduncle length 17 18.3 ± 1.1 16.3-20.0 19.7 19.0±1.3 16.5-21.4 18.6 18.1±0.8 17.1-19.2 18.9 Caudal peduncle depth 12.3 12.7 ± 0.4 11.9-13.3 12.6 12.4±0.4 11.6-13.1 12.6 12.5±0.2 12.3-12.8 11.2 As percent of head length Cheek depth 19.5 22.6 ±1.8 19.3-26.5 25.7 25.2 ±1.1 23.2-28 26.6 25.8±1.5 23.2-28.1 31.3 Head depth 81 78.7±2.9 73.0-84.1 74.3 79.4 ±2.6 74.3-82.9 76.9 76.7 ±1.3 75.5-79.3 78.8 Horizontal eye diameter 34 34.7±1.9 32.6-39.7 32.4 32.6 ±1.5 30.5-35.6 30.4 32.1±1.3 30.4-34.5 32.9 Vertical eye diameter 34.3 33.7±1.8 30.7-37.5 31.5 31.6 ±1.8 28.5-34.8 29.8 31.6 ±0.9 29.8-32.5 32.5 Interorbital width 19.2 19.8±0.8 18.3-21.4 17.4 16.9 ±1.0 14.3-18.5 62.7 18.1 ±0.8 17.3-19.7 19.2 Lower jaw length 40.5 39.1 ±1.0 37.1-40.7 42.2 44.3 ±1.0 42.2-46.3 42.6 39.6 ±1.4 38.0-42.6 41.7 Premaxillary pedicel length 26.8 26.3 ±1.3 24.2-29.3 24.5 24.8 ±0.9 23.2-26.3 25.4 25.2 ±0.9 23.6-26.1 26 Preorbital bone depth 17.4 17.7 ±0.8 15.5-19.1 16.5 16.4 ±0.9 14.5-19 17 17.3 ±0.6 16.7-18.6 18.7 Postorbital head length 35.6 36.6 ±1.4 33.8-39.3 38.8 37.8 ±1.2 35.5-40.3 41.2 39.9 ±1.1 37.7-41.2 38.9 Snout length 29.4 28.0 ±1.6 24.7-31.8 29.4 28.1±1.1 26.1-30.5 28.4 28.8±0.6 27.8-29.9 31.3

As percent of maximum depth Maximum width 41.5 43.3 ±1.3 40.2-45.5 44.8 46.6 ±1.7 44.2-49.7 45.7 47.9 ±1.7 45.7-50.8 45.9 Caudal peduncle length/depth 1.4 1.4 ±0.1 1.3-1.6 1.6 1.5 ±0.1 1.3-1.8 1.5 1.4 ±0.1 1.3-1.5 1.7

4.5.0 Diplotaxodon limnothrissa Turner, 1994

Type locality. Monkey Bay, Southeast arm Lake Malaŵi.

Type. BMNH 1992.3.25.1

Diagnosis. Smaller, more slender and elongated (117.7-185.4 mm) (see Fig. 12) than congenerics, with smaller lower jaw length and eyes (24-33% and 25-29% HL respectively).

There are no spots or stripes on the body. Head length between 28-34% SL smaller than

Diplotaxodon apogon, Diplotaxodon ecclesi Diplotaxodon aeneus and Diplotaxodon greenwoodi (35.5-37.6%, 35.5%, 38.5-40.6% and 42.1-75.1% SL respectively). Smaller body depth than D. greenwoodi, D. macrops, D. apogon and D. aeneus (26-30% SL versus

34.2-36.5%, 33.5-36.8%, 32.4-37.3 and 34.3-37.1% SL respectively). Lateral-line scales more than D. greenwoodi (36-39 vs 34). Small mouth, numerous set of teeth. Premaxillaries lack beak like structure present in D. greenwoodi. Gill rakers in the outer arch of ceratobranchial more than D. greenwoodi (20-26 versus 10-11).

Description. Morphometric ratios and meristic data in Table 4. Small head moderately concave in profile above eye (Fig. 13). Premaxillary pedicel moderately noticeable. Lower jaw slightly protruded with upper and lower lips meeting at their rostral ends. Posterior end of the maxilla anterior to the nostrils and eyes. Pectoral fins short and not to vent. Caudal fin moderately forked with many scales basally. Longest rays of the dorsal and anal fin not to base of caudal fin. Two rows of scales between the upper and lower lateral lines and 2-3 rows of scale on cheek. Outer arch of epibranchial with 6-10 gill rakers; outer arch of ceratobranchial with 20-26. Two series of teeth in both upper and lower jaws.

Figure 13: Male Diplotaxodon limnothrissa, at the beginning to develop breeding dress,

Holotype collected in 1991 is in the British Museum (Source:http://www.fishbase.org).

Table 4: Morphometric and meristic values of type series of Diplotaxodon limnothrissa (n=

23) with mean, standard deviation and range of the population sampled from commercial vessel at Domira Bay in 2012

Variable Mean SD Range

Standard length, mm 141.57 19.67 117.7-185.4

Head length, mm 49.30 9.67 36-73.3

Percent of standard length

Body depth 29.96 3.87 25-38

Snout to dorsal-fin origin 37.61 2.90 31-43

Snout to pelvic-fin origin 40.30 1.89 37-46

Dorsal fin base length 48.30 2.29 42-51

Anterior dorsal to anterior anal 43.74 1.39 41-46

Anterior dorsal to posterior anal 53.13 1.87 49-56

Posterior dorsal to anterior anal 26.61 1.83 24-31

Posterior dorsal to posterior anal 15.26 0.81 14-17

Posterior dorsal ventral caudal 22.13 1.25 20-24

Posterior anal to dorsal caudal 22.22 1.13 20-24

Anterior dorsal to pelvic-fin origin 50.52 2.81 47-59

Posterior dorsal to pelvic-fin origin 25.52 4.41 19-33 caudal peduncle length 16.65 2.60 12-21

Least caudal peduncle depth 10.83 1.64 8-13

Percent of head length

Snout length 34.91 2.19 32-40

Postorbital head length 36.35 2.06 33-40

Horizontal eye diameter 26.65 1.27 25-29

Vertical eye diameter 26.78 1.20 25-29

Preorbital depth 19.52 2.27 15-27

Cheek depth 15.87 1.69 13-19 lower jaw length 28.22 2.35 24-33

Head depth 64.87 5.07 54-78

Counts Mode Frequency % Range

Dorsal-fin spines 16 56.52 15-16

Dorsal-fin rays 12 78.26 12-13 anal-fin spines 3 100 3-3

Anal-fin rays 10 78.26 9-11

Pelvic-fin rays 5 100 5-5

Pectoral-fin rays 13 91.3 11-13

Lateral line scale 35 39.13 33-36

Pored scale posterior to lateral line 1 60.87 1-3

Scale rows on cheek 2 100 2-2

Gill rakers on first epibranchial 6 47.83 6-9

Gill rakers on first ceratobranchial 23 39.13 18-25

Teeth in outer row of left lower jaw 34 52.17 32-37

Teeth rows on upper jaw 2 100 2-2

Teeth rows on lower jaw 2 95.65 2-3

Table 5: The Sheared principal components (PC2) and Unsheared Principle component (PC2) variable loadings on size for D. greenwoodi and D. limnothrissa

Sheared unsheared Variable Size PC2 Size PC2

Standard length -0.169 0.045 0.035 0.004

Head length -0.231 0.069 0.056 -0.056

Snout length -0.297 0.057 0.040 -0.027

Pre-orbital head length OHL -0.194 0.119 0.108 0.031

Horizontal eye diameter -0.218 0.058 0.045 -0.082

Vertical eye diameter -0.224 0.049 0.036 -0.046

Pre-orbital eye diameter -0.225 -0.003 -0.016 0.90*

Cheek depth -0.304 -0.132 -0.150 0.018

Lower jaw length -0.313 -0.002 -0.021 -0.109

Head depth -0.210 0.058 0.045 -0.34*

Body depth -0.276 -0.22* -0.231 -0.083

Snout to dorsal fin origin -0.247 0.052 0.037 0.045

Snout to pelvic fin -0.214 0.075 0.063 -0.051

Dorsal fin base length -0.132 -0.015 -0.023 0.033

Anterior dorsal to anterior anal fin -0.176 -0.064 -0.074 0.033

Anterior dorsal to posterior anal fin -0.152 -0.023 -0.032 0.008

Posterior dorsal to anterior anal fin -0.209 -0.081 -0.094 -0.108

Posterior dorsal to posterior anal -0.198 -0.008 -0.020 -0.082

Posterior dorsal to ventral caudal -0.146 0.127 0.119 0.046

Posterior anal dorsal caudal -0.135 0.123 0.115 -0.024

Anterior dorsal to pelvic origin -0.179 -0.054 -0.065 -0.013

Posterior dorsal to pelvic fin origin 0.014 0.68* 0.682 0.017

Caudal peduncle length 0.005 0.39* 0.389 -0.086

Least caudal peduncle depth 0.013 0.48* 0.481 0.059

* Highest loadings for a particular variable (sheared and unsheared)

Table 6: The principle component analysis PC1 (meristic) and their standardized scoring coefficients for D. greenwoodi and D. limnothrissa

Variable Factor1 Factor2

Dorsal fin spine -0.19* 0.172

Dorsal fin Rays -0.040 0.33*

Anal fin spine 0.000 0.000

Anal fin ray -0.023 -0.010

Pelvic fin ray 0.000 0.000

Pectoral fin rays 0.017 0.189

Lateral line scale -0.061 0.295

Pored Scales Past Lateral Line -0.055 -0.012

Scale rows on the cheek 0.48* 0.052

Gill rakers on ceratobranchial -0.12* 0.091

Gill rakers on epibranchial -0.20* 0.106

Teeth outer row of left lower jaw 0.100 0.35*

Teeth rows on upper jaw 0.000 0.000

Teeth rows on lower jaw 0.19* 0.23*

* Highest scorings

The variables with the highest loadings on the PC1 based on the standardized scoring coefficients were Dorsal fin spine (-0. 19), Scale rows on the cheek (0.41) gill rakers on epibranchial (-0.20), gill raker on ceratobranchial (-0.12) and teeth on lower left jaw (0.19)

(Table 6). While for shape factors (SPC) the highest loadings were body depth (-0.22), posterior dorsal fin origin to posterior anal (0.68), caudal peduncle length (0.39) and least caudal peduncle depth (0.48) (Table 5).

0.3 )

a D. greenwoodi t

a D. limnothrissa d

0.2

e m

o 0.1

(

2 0.0

R -0.1

H S

-0.2 -1 0 1 2 3 4 5 PC1 (meristic data)

Figure 14: Plots of the sheared second principle components (morphological data) and the first factor score, first principle component (meristic data) for Diplotaxodon greenwoodi and

Diplotaxodon limnothrissa sampled from commercial vessel in Domira Bay, Lake Malaŵi in

2012

The morphology of D. limnothrissa (fig 13) are extraordinarily distinguishable from D. greenwoodi (fig 15).The clusters were significantly different for D. limnothrissa and D. greenwoodi. The minimum polygons, sheared second principal components of the morphometric data were plotted against the first principal components of the meristic data were significantly (p<0.05) different along both the morphometric data and meristic axis

(Fig. 14). D. greenwoodi is considered as a larger species compared to D. limnothrissa with mean standard length and head length of 198.7mm and 71.4mm as compared to 141mm and

49mm respectively (see Tables 4 & 7).

4.6.0 Diplotaxodon greenwoodi Stauffer &McKaye, 1986

Type locality. Off Monkey Bay, Lake Malaŵi.

Type: USNM 270847

Diagnosis. Increased gape inclination (Fig 14) between 57-66 degrees. Distinguishes from other Diplotaxodon spp. has fourth row of teeth in the upper jaw.

Description. Morphometric ratios and meristic data in Table 5. Body moderately compressed, body width between 34.2-36.5 % SL. Distance between snout and dorsal-fin origin between

38.2-40.4% SL. Distance between snout and pelvic-fin origin between 45.2-47.2% HL. Head length between 37.4-38.1% SL. Eyes large and horizontal eye diameter between 27.5-35.4%

HL. Cheek with 2-3 rows of scales. Mean length of lower jaw 48.7% HL. Teeth on lower jaw in 2-3 rows and teeth on the upper jaw in four rows. Small ventral protrusion at sympysis of dentries. Gill rakers on outher arch of ceratobranchial between 19-20 and on outer arch of epibranchial 6, Mean dorsal-fin base length 44.7% SL. Pectoral fins with 12-13 segmented rays. Anal fins with three spines and 10-11 segmented rays. Lateral-line scales 34. Dark

dorsally, with purple sheen. Lateral surface silver; white ventrally and no dark spots or stripes.

Distribution. Morphometric ratios and meristic data in Table 7. Collection of the holotype was 8km south of Mumbo Island in the Nankumba Peninsula/Cape Maclear in 1984.

It occurs in the open water and it is indicate to be found in some areas as down to 150 m but has been mostly captured in trawls in small numbers at around 50 m. It is widely distributed in the southern part of the lake and has been reported near Nkhata bay and at Chizumulu

(Kasembe 2006). Turner (1994) noted that D. limnothrissa was found in areas ranging between 20-126m. The species was never found in seine net catches in southern Lake Malawi or Lake Malombe, and did not appear to enter waters less than 20m deep (Turner 1994). At the time of reporting, Turner (1998) found that the species was the most abundant haplochromine cichlids in from commercial trawl operating between Boadzulu Island and

Monkey Bay in south east arm of Lake Malaŵi. Turner (1998) also collected D. limnothrissa near Maleri Islands and off Mbenji Island in Domira Bay.

Figure 15: Diplotaxodon greenwoodi specimen from Pennsylvania State University fish

Museum (Photo: Ad Connings).

Table 7: Principal morphometric and meristic characteristics of Diplotaxodon greenwoodi (n=4 and includes holotype). (Source: Proceedings of Biological Society of Washington 99(1), 1986, pp. 29-33)

Variable Holotype Mean Range SD

Standard length, mm 198.7 154.5 111.9-198.7 37.1

Head length, mm 75.1 58.3 42.1-75.1 14.2

Percent of Head Length

Horizontal eye diameter 275 309 27.6-35.4 34

Vertical eye diameter 278 310 27.8-35.2 33

Snout length 317 299 24.2-34.2 43

Postorbital head length 406 389 38.0-40.6 12

Premaxillary pedicel 173 191 17.3-20.0 13

Lower jaw length 519 487 46.0-51.9 25

Interorbital width 189 176 16.6-19.3 18

Cheek depth 217 185 15.9-20.1 28

Head depth 870 850 82.4-87.0 21

Percent of Standard Length

378 377 37.4-38.1 3 Head length, mm

Snout to dorsal 383 396 38.3-40.4 10

Snout to pelvic 453 459 45.3-47.2 9

Body depth 355 354 34.2-36.5 9

Least caudal peduncle length 196 185 16.8-19.6 14

Least caudal peduncle depth 113 112 10.9-11.5 3

Pectoral fin length 329 320 30.6-33.2 13

Pelvic fin length 199 198 18.0-21.0 13

Dorsal fin base length 459 447 42.6-45.9 15

Gape inclination (degrees) 63 62.3 57-66 3.8

Lateral line scales 34 34 34 -

Scale rows on cheek 2 2.5 2-3 0.58

pectoral fin rays 13 12.5 12-13 0.58

pelvic fin rays 5 5 5 -

Anal fin spines 3 3 3 -

Anal fin rays 10 10.3 10-11 0.5

Gill rakers on ceratobranchial 20 19.3 19-20 0.5

Gill rakers on epibranchial 6 5.3 5-6 0.5

The minimum polygons sheared second principal components of the morphometric data plotted against the first principal components of the meristic data were significantly (p<0.05) different along both the morphometric and meristic data (Fig. 16).

Table 8: The Sheared principal components (PC2) and Unsheared Principle component (PC2) variable loadings on size for D. greenwoodi and D. apogon

Sheared Unsheared Variable Size PC-2 Size PC-2

Standard length -0.176 0.093 0.033 -0.076

Head length -0.234 0.055 -0.035 0.017

Snout length -0.254 0.169 0.072 -0.002

Pre-orbital head length -0.175 0.198 0.137 -0.192

Horizontal eye diameter -0.372 -0.32* -0.447 0.28*

Vertical eye diameter -0.376 -0.31* -0.445 0.29*

Pre-orbital eye diameter -0.193 0.010 -0.047 -0.047

Cheek depth -0.273 0.135 0.043 -0.53*

Lower jaw length -0.280 -0.031 -0.142 0.075

Head depth -0.238 -0.021 -0.118 -0.015

Body depth -0.182 -0.007 -0.093 0.088

Snout to dorsal fin origin -0.239 0.017 -0.073 0.080

Snout to pelvic fin origin -0.200 0.068 -0.010 -0.009

Dorsal fin base length -0.106 0.135 0.104 -0.20*

Anterior dorsal to anterior anal -0.120 0.117 0.078 -0.168

Anterior dorsal to posterior anal -0.104 0.119 0.081 -0.179

Posterior dorsal to anterior anal -0.155 0.124 0.060 -0.207

Posterior dorsal to posterior anal -0.118 0.087 0.028 -0.103

Posterior dorsal to ventral caudal -0.175 0.183 0.127 0.047

Posterior anal to dorsal caudal -0.166 0.175 0.121 0.010

Anterior dorsal to pelvic fin origin -0.118 0.117 0.070 -0.104

Posterior dorsal to pelvic fin origin -0.046 0.32* 0.286 0.23*

Caudal peduncle length 0.106 0.51* 0.511 0.42*

Least caudal peduncle depth 0.056 0.35* 0.342 0.31*

* Highest loadings for variable (sheared and unsheared)

Table 9: The Principle Component Analysis PC1 (meristic) and their standardized scoring coefficients for D. greenwoodi and D. apogon

Variable Factor1 Factor2

Dorsal fin spines -0.08 0.2*

Dorsal fin rays 0.00 -0.05

Anal fin rays 0.01 -0.03

Lateral line scale 0.04 0.3*

Cheek scales 0.6* -0.3*

Gill rakers on ceratobranchial -0.02 0.17

Gill rakers on epibranchial -0.15 -0.13

Teeth on lower left jaw 0.2* -0.03

* Highest loadings

0.4 D. apogon

D. greenwoodi

) a

t 0.3

c i

r 0.2

o h

p 0.1

(

2 0.0

D R

H -0.1 S

-0.2 -1 0 1 2 3 PC1 (meristic data)

Figure 16: Plots of the sheared second principle components (morphological data) and the first factor score, first principle component (meristic data) for Diplotaxodon apogon and

Diplotaxodon greenwoodi sampled from commercial vessel in Domira Bay, Lake Malaŵi in

2012

The plot of D. greenwoodi and D. apogon had minimum polygons did not overlapped

(Fig 16). The variables with the highest loadings on the PC1 based on the standardized scoring coefficients were Scale rows on the cheek (0.61) and teeth on the lower left jaw

(0.21) for factor 1, dorsal spines (0.21) lateral line scales (0.3) and Scale rows on the cheek (- 37

0.3) for factor 2 (Table 9). Shape factors (SPC) the highest loadings were posterior eye diameter (-0.32), posterior dorsal fin origin to posterior anal (0.32), caudal peduncle length

(0.51) and least caudal peduncle depth (0.35) for the sheared (Table 8).

4.7.0 Diplotaxodon argenteus Trewavas, 1935

Type locality. Off Monkey Bay, Lake Malaŵi.

Type: USNM 270847. 99(1): 29-33

Diagnosis. Eye diameter shorter than D. macrops (24-33% versus 33-40% HL).

Differs from D. limnothrissa mouth smaller than D. greenwoodi (lower jaw 14-16% versus

46-51.9% HL). Distinguished from D. altus and D. greenwoodi having more slander body.

Differs D. altus in larger eyes with wider inter orbital. Higher number of gill rakers in the range of 21-27 ceretobranchials. Shallow body flat dorsal profile. upturned mouth strongly protruding lower jaw (Fig 17).

Description. Morphometric ratios and meristic data in Table 6. Ripe males silvery dusky dorsum and head. Black eyes, snout and (dorsal, anal, caudal and pelvic) fins. Large 1-

2 yellow egg-spots on anal (Turner 1996).

Distribution. It can be found in depth range 34 - 114 m. It is common in the southern part of the lake although found throughout. It is common catches from trawl nets cast between 34–114 m and from 50-125m in the southwestern arm of the lake. It is considered as a mid-water spawner, in the south western arm 60% of breeding males were caught at 75 m while ripe females were caught between 75-125 m. It occurs as by catch in the mid water trawl catches and also occurs in the catches of deep-water demersal trawls as well as chilimira nets and hand-lines (Kasembe 2006).

Figure 17: Diplotaxodon argenteus, a benthopelagic fish species; (Photo source: malawicichlids.com)

Table 10: Morphometric and meristic values of type series of Diplotaxodon argenteus (n=

11) with mean, standard deviation and range of the population including the holotye sampled from commercial vessel at Domira Bay in 2012-2013

Variable Mean SD Range

Standard length, mm 134.13 25.03 104.6-177.7

Head length, mm 48.97 12.50 33.7-67.9

Percent of standard length

Body depth 30.09 3.21 25-35

Snout to dorsal-fin origin 39.45 4.01 33-45

Snout to pelvic-fin origin 41.00 2.28 37-43

Dorsal fin base length 47.73 2.57 44-51

Anterior dorsal to anterior anal 43.73 2.15 41-48

Anterior dorsal to posterior anal 52.45 1.97 49-56

Posterior dorsal to anterior anal 26.64 1.36 25-29

Posterior dorsal to posterior anal 15.82 0.98 15-15

Posterior dorsal ventral caudal 22.09 1.22 21-24

Posterior anal to dorsal caudal 22.73 1.10 21-24

Anterior dorsal to pelvic-fin origin 48.91 2.21 44-52

Posterior dorsal to pelvic-fin origin 40.36 9.51 25-52

Caudal peduncle length 22.55 5.87 13-32

Least caudal peduncle depth 15.27 3.47 10-20

Percent of head length

Snout length 33.73 2.97 30-38

Postorbital head length 37.18 1.25 36-40

Horizontal eye diameter 28.00 2.65 24-33

Vertical eye diameter 28.09 3.08 24-33

Preorbital depth 19.00 1.48 16-21

Cheek depth 15.27 1.95 12-18

Lower jaw length 29.45 2.34 26-32

Head depth 64.45 2.66 60-71

Counts Mode Frequency % Range

Dorsal-fin spines 14 61.54 14-16

Dorsal-fin rays 12 46.15 11-13

Anal-fin spines 3 100 3

Anal-fin rays 10 76.92 10-11

Pelvic-fin rays 5 100 5

Pectoral-fin rays 13 84.62 11-13

Lateral line scale 34 30.77 32-35

Pored scale posterior to lateral line 1 61.54 1-2

Scale rows on cheek 2 92.31 2-3

Gill rakers on first epibranchial 5 38.46 4-8

Gill rakers on first ceratobranchial 17 46.15 17-23

Teeth in outer row of left lower jaw 33 46.15 32-34

Teeth rows on upper jaw 2 92.31 2-3

Teeth rows on lower jaw 2 53.85 2-3

Morphologically D. argenteus (Fig 17) is more similar to D. limnothrissa (Fig 13), however the clusters formed when plotting the SPCA2 against the PCA of the meristic data indicated that they are different. The polygons sheared second principal components of the morphometric data plotted against the first principal components of the meristic data were significantly (p<0.05) different along both the morphometric and meristic data (Fig. 18).

Table 11: The Sheared principal components (PC2) and Unsheared Principle component

(PC2) variable loadings on size for D. argenteus and D. limnothrissa.

Sheared Unsheared Variable Size PC_2 Size PC_2

Standard length -0.172 -0.066 -0.060 0.197

Head length -0.241 0.047 0.055 0.024

Snout length -0.311 0.004 0.015 0.055

Postorbital head length -0.214 0.069 0.076 0.161

Horizontal eye diameter -0.201 0.138 0.145 -0.157

Vertical eye diameter -0.200 0.127 0.134 -0.185

Preorbital depth -0.249 -0.012 -0.003 0.41*

Cheek depth -0.307 0.058 0.069 -0.443*

Lower jaw length -0.314 0.133 0.144 -0.139

Head depth -0.217 0.024 0.031 -0.039

Body depth -0.247 -0.022 -0.014 -0.401*

Snout to dorsal fin origin -0.252 0.074 0.082 0.020

Snout to pelvic fin origin -0.214 0.002 0.010 0.064

Dorsal fin base length -0.134 -0.121 -0.116 0.255

Anterior dorsal to anterior anal -0.162 -0.081 -0.075 0.086

Anterior dorsal to posterior anal -0.149 -0.110 -0.105 0.171

Posterior dorsal to anterior anal -0.201 -0.053 -0.046 -0.089

Posterior dorsal to anterior anal -0.191 -0.006 0.001 0.017

Posterior dorsal to ventral caudal -0.151 -0.073 -0.067 0.295

Posterior anal to dorsal caudal -0.151 -0.041 -0.036 0.248

Anterior dorsal to pelvic fin Origin -0.162 -0.131 -0.125 0.074

Posterior dorsal to pelvic fin origin 0.033 0.680* 0.678 0.203

Caudal peduncle length 0.033 0.415* 0.414 -0.038

Least caudal peduncle depth 0.027 0.481* 0.480 0.117

* Highest loadings for variable (sheared and unsheared)

Table 12: The principle component analysis PC1 (meristic) variables and their standardized scoring coefficients for D. argenteus and D. limnothrissa

Varable Factor1 Factor2

Dorsal fin spines 0.21* 0.075

Dorsal fin rays 0.165 0.181

Anal fin spines 0.000 0.000

Anal fin rays 0.014 -0.003

Pelvic fin rays 0.000 0.000

Pectoral fin rays 0.076 0.166

Lateral line scale 0.181 0.124

Pored scale posterior to lateral line 0.016 0.176

Scale rows on cheek -0.26* 0.73*

Gill rakers on first ceratobranchial 0.21* 0.004

Gill rakers on first epibranchial 0.21* 0.049

Teeth in outer row of left lower jaw 0.079 0.249

Teeth rows on upper jaw 0.000 0.000

Teeth rows on lower jaw -0.153 0.142

* Highest loadings

D. argenteus

0.3 D. limnothrissa

)

a t

a 0.2

t e

m 0.1

o m

( 0.0

D -0.1

H S

-0.2

-3 -2 -1 0 1 2 PC1 (meristic data)

Figure 18: Plots of the sheared second principle components (morphological data) and the first factor score, first principle component (meristic data) for Diplotaxodon argenteus and

Diplotaxodon limnothrissa sampled from commercial vessel in Domira Bay, Lake Malaŵi in

2012

The variables with the highest loadings on the PC1 based on the standardized scoring coefficients were Dorsal fin rays (0.21), Scale rows on the cheek (-0.26) on both factors gill rakers on epibranchial (0.21) and ceratobranchial (0.21) (Table 12). While for shape factors

(SPC) the highest loadings were posterior dorsal fin origin to posterior anal 0..68), caudal peduncle length (0.42) and least caudal peduncle depth (0.41) (Table 11).

5.0.0. Overview of undescribed species.

A couple of species in the genus remains undescribed despite being discovered. The last species were described in 1998, almost 15 years has passed. It was assumed that the species lack distinct features that can discrete them from the described species. Most of the undescribed species in the genus Diplotaxodon have cheironym (Table 13) that are either too temporal or not well documented.

Table 13: List of possible existing but undescribed species in the genus Diplotaxodon and their taxonomic status

No. Provisional name Taxonomic Status 1 Diplotaxodon ‗brevimaxillaris’ Invalid name, op.cit., redescribed, n. nov. §

ᴪ 2 Diplotaxodon ‗bigeye‘ Working name, sp. ind. , op. cit. Ω

3 Diplotaxodon ‗ngulube‘ Provisional name, sp. ind, op. cit.

4 Diplotaxodon ‗similis‘ Invalid name, sp. ind, op. cit.

5 Diplotaxodon ‗white belly‘ Provisional name, sp. ind, op. cit.

6 Diplotaxodon ‗holochromis‘ Invalid name, sp. ind, op. cit.

7 Diplotaxodon ‗offshore‘ Provisional name, sp. ind, op. cit.

8 Diplotaxodon ‗intermediate‘ Provisional name, sp. ind, op. cit.

9 Diplotaxodon ‗macrostoma‘ Invalid name, sp. ind, op. cit.

10 Diplotaxodon ‗molted‘ Working name, sp. Ind.

11 Diplotaxodon ‗white top‘ Working name. sp. ind.

12 Diplotaxodon ‗deep‘ Invalid name, redescribed n. nov

13 Diplotaxodon ‗large black‘ Provisional name, sp. ind

14 Diplotaxodon ‗thick‘ Provisional name, sp. ind, op. cit.

15 Diplotaxodon ‗black fin‘ Provisional name, sp. ind , op. cit.

§ ᴪ n. nov is nomen novum meaning new name, proposed for as a direct substitution for an invalid existing name. sp. ind is species indeterminate meaning species of doubtful identity, need further investigation. Ω op. cit is Opere citato meaning publication cited.

There are more interim names found in literature that were given to undescribed

Diplotaxodon spp. and have not been included in Table 13. The interim names that were given in relation to the location (such as Diplotaxodon ‘mosambique‘) that were found have deliberately not been included in the list. The fact that there is no proper documentation for such undescribed spp., it is not hard not to suspect that it might refer to same spp. listed in the table because such names do not give any hypothesized characteristic to refer to a particular fish species. Diplotaxodon ‗similis‘ was confused with D. argenteus in many previous studies and D. ‗offshore‘ was previously known as D. ‗bigeye‘(Snoeks et al. 2004 ).

CHAPTER 2

6.0.0 DESCRIPTION OF TWO NEW SPECIES

6.1.0. INTRODUCTION

Fish species in the genus Diplotaxodon are haplochromine cichlids endemic to Lake

Malaŵi. The main synapomorphic character of Cichlidae is supported by the morphology of the otoliths (Stauffer et al. 2007). There are no concrete figures on the number of genera and species in Cichlidae because there are still many revisions being made and a considerable number of species are yet to be described (Myers et al. 2013). The cichlid species that flock in Lake Malaŵi are considered as one of the most complicated assemblages of species in existence (Konings 1995). The phylogenetic relationships and the distribution of Cichlids suggest that the family was adequately developed before the separation of Gondwanaland

(Stauffer et al. 2007).

Kocher (2004) stated that rapid radiation of cichlids in east Africa has posed a challenge to those attempting to reconstruct the historical relationships among species. He further explains that the radiation in Lake Malaŵi can be characterized in three historical stages; habitat divergence (rock and sand dwelling clades), morphologically distinct genera

(feeding apparatus differentiation), and color pattern (action of sexual selection). It has been difficult to investigate both phylogenetics and genetics of cichlids of Lake Malaŵi because the species tend to share much of their genetic variation (Won et al. 2001). And Won (2005) explains that the absence of phylogenetics assessments makes it very difficult to know as to what degree recent speciation and questions if genetic variation is as a result of gene exchange. There had been several concepts/hypotheses to suggest the existing close relationships of cichlids of Lake Malaŵi. Some studies have shown that there is a possibility of hybridization as evident on the studies on Cynotilapia afra. Stauffer et al. (1996) observed

that the introduction of northern populations of Cynotilapia afra to areas in Cape Maclear, where they were not native had variations in color and intermediate dentition.

Some species of the genus Diplotaxodon move vertically in the water column.

Diplotaxodon ‗bigeye‘ was recorded in the depth of 3m at full moon at night and during the day was always recorded from deeper than 150m and usually at 220m (Thompson et al.

1996); thus, they can support both the commercial and traditional Chilimira fishery.

Fisheries in Lake Malaŵi showed that most of the exploited species in the South East and South West arms also occur in the non-exploited trawling grounds between Domira Bay and Nkhata Bay (Duponchelle et al. 2000, Banda and TÓmasson 1996).

Male color is of tremendous utility in determining if more than one species is present and it is obviously of no value in the identification of female and immature fishes (Turner &

Stauffer 1998). Species within the genus of Diplotaxodon differ in monochromatic patterning on the bodies and fins of males (Genner 2007). Genner (2007) further indicated that all known female juvenile individuals in the genus of Diplotaxodon have plain silver bodies, largely translucent fins and lack any conspicuous melanin markings. It has however been noted that male breeding color pattern of D. ecclesi is very similar to that of D. macrops and the reported type localities are in the same area (Turner & Stauffer 1998).The range of color hues visible to fishes is dependent not only on their optical capabilities, but also upon local environmental regimes. Some habitats have narrow ambient light spectra due to selective absorption of wavelengths (Genner 2006).Thompson et al. (1996) indicated that in Lake

Malaŵi, cichlids occupy most of the pelagic habitats, although their relatively low reproductive output prevents them from supporting a robust fishery.

Seven species in the genus Diplotaxodon have been formally described with collections from different places of Lake Malaŵi. This study was strategically conducted in Salima

District, to capture data from semi commercial and commercial fishery in southern part of

Lake Malaŵi. Data from the commercial fisheries reveals that Diplotaxodon catches are 48

considerably higher than those of other species. Fisheries Policy (2012) recognizes that commercial fishing is done in the waters between 50 m to 130 m deep and mainly target species in the genus Diplotaxodon. It can be presumed that in shorter period from now some of the species may start disappearing from most areas. Establishing the information on these important species will provide the basis for the management of the resource.

The main aim of this chapter is to formally describe two new species in the genus

Diplotaxodon which had working names of ―brevimaxillaris‖ and ―deep‖ by examining their morphological and meristic characteristics.

7.0.0 New species of Diplotaxodon

Diplotaxodon altus n. sp., n. nov (nova species, novem nomen) (Fig. 18)

Diplotaxodon sp. ‘deep’.

Holotype (1) PSU12501: Male collected from trawl net at a depth below 70m, sourtheast of

Senga Bay, Lake Malaŵi, in January 2013. Collected by T. Phiri

Paratype (3) PSU12502, LUANARB02 (2). Collected from trawl net at a depth below 70m, sourtheast of Senga Bay, Lake Malaŵi, in January 2013. Collected by T. Phiri

Diagnosis. Eye diameter longer than the snout length which distinguished it from D. greenwoodi, D. argenteus and D. limnothrissa. Body depth (31-41% SL) longer than D. limnothrissa (26-30% HL).Has 17-19 gill rakers on ceratobranchial which lower than D. macrops and D. argenteus (20-25 and 21-27 respectively). Lower Jaw length is 31-34% HL shorter than of D. ecclesi, D. aeneus, D. macrops, D. greenwoodi and D. apogon; 41.7%, 38-

42.6%, 37.1-40.7%, 46-51.9% and 42.2-46.3% HL respectively. Dorsal-fin spines between

14-16, more than D. apogon (12-14).

Description. Morphometric ratios and meristic data in Table 14. Large eyes (33-37%

HL). Deep bodied. Body laterally compressed. Head concave just above eye. Lower jaw slightly convex. Premaxillary with small beak. Pectoral fin long reaching beyond vent, longest ray no to first anal-fin spine. Pelvic fin of female short, not to vent. Longest ray of anal and dorsal fin to half-length of caudal peduncle. Caudal fin emarginated. Small ctenoid scales. Number of scales on lateral line between 34-35; lower lateral line short but straight.

Two series of scales between upper and lower lateral line at anterior end of lower lateral line.

One series of scales posterior between upper and lower lateral line. One scale series between lateral line and posterior of dorsal fin. Cheek fully scaled with 3 rows of scales. Outer arch of epibranchial with 6 gill rakers; outer arch of ceratobranchial with 17-19. Gill rakers on ceratobranchial longer. Teeth curved inwardly in two series on upper and lower jaws.

Mature fish dark grey dorsally; light white ventrally. Bars, stripes, saddles or blotches absent. 50

Distribution. Diplotaxodon altus is found in offshore, deep water environments. It is rare compared with other species in the genus, but is common in Chilimira seine nets at depths below 70m. Samples for the description were collected southeast of Senga Bay. It has also been reported Nkhata Bay and is known to be from Nkhotakota area and Metangula

(www.cichlids.dk)

Etymology. The specific name ‗altus‘ is derived from a Latin word which means deep and this was to refer to the deep body of fish also from deep water and did not want to change the conceptualized name ‗deep‘ as the species has for long been referred to before it was described.

Figure 19: A fin clipped female Diplotaxodon altus from collected from Senga Bay, northeast of Chipoka, Lake Malawi. (Photo: by Evance Samikwa 2013).

7.1.0 Results

Table 14: Morphometric and meristic values of type series of Diplotaxodon altus (n= 18) with mean, standard deviation and range of the population including the holotype sampled from Senga Bay and Domira Bay in 2012-2013

Variable Holotype Mean SD Range

Standard length, mm 153.91 159.00 38.90 104.1-192.9

Head length, mm 54.76 60.85 15.11 41.3-77

Percent of standard length

Body depth 55.37 34.50 4.51 31-41

Snout to dorsal-fin origin 61.36 42.25 0.96 41-43

Snout to pelvic-fin origin 62.85 43.25 1.26 42-45

Dorsal fin base length 72.8 44.25 2.63 42-48

Anterior dorsal to anterior anal 69.23 42.00 1.41 40-43

Anterior dorsal to posterior anal 81.97 50.50 1.73 49-53

Posterior dorsal to anterior anal 43.73 27.50 1.29 26-29

Posterior dorsal to posterior anal 23.51 15.00 0.82 14-16

Posterior dorsal ventral caudal 31.16 21.75 0.50 21-22

Posterior anal to dorsal caudal 31.14 22.50 0.58 22-23

Anterior dorsal to pelvic-fin origin 55.94 42.00 14.21 21-52

Posterior dorsal to pelvic-fin origin 82.86 38.50 10.66 30-53 caudal peduncle length 23.75 15.75 4.27 13-22

Least caudal peduncle depth 18.52 12.75 3.59 10-18

Percent of head length

Snout length 20.59 36.00 3.16 32-39

Postorbital head length 19.41 34.00 0.82 33-35

Horizontal eye diameter 13.92 27.50 3.42 33-37

Vertical eye diameter 14.36 27.75 3.59 33-37

Pre-orbital depth 13.17 18.75 1.89 16-20

Cheek depth 9.61 16.75 2.50 14-20 lower jaw length 16.14 32.25 1.50 31-34

Head depth 29.73 67.25 3.77 63-72

Counts Mode Frequency % Range

Dorsal-fin spines 16 15 50 14-16

Dorsal-fin rays 14 12 50 12-14 anal-fin spines 3 3 100 3-3

Anal-fin rays 11 11 100 11-11

Pelvic-fin rays 5 5 100 5-5

Pectoral-fin rays 13 13 100 13-13

Lateral line scale 34 35 75 34-35

Pored scale posterior to lateral line 1 1 100 1-1

Scale rows on cheek 3 3 100 3-3

Gill rakers on first epibranchial 6 6 100 6-6

Gill rakers on first ceratobranchial 19 19 50 17-19

Teeth in outer row of left lower jaw 33 33 100 33-33

Teeth rows on upper jaw 2 2 100 2-2

Teeth rows on lower jaw 2 2 100 2-2

Table 15: The Sheared principal components (PC2) and Unsheared Principle component

(PC2) variable loadings on size for D. altus and D. apogon.

Sheared Unsheared Variable Size PC-2 Size PC-2

Standard length -0.221 0.115 0.169 -0.051

Head length -0.224 -0.090 -0.030 -0.001

Snout length -0.283 -0.036 0.039 -0.066

Post orbital head length -0.226 0.082 0.141 -0.006

Horizontal eye diameter -0.178 -0.31* -0.269 0.049

Vertical eye diameter -0.182 -0.31* -0.266 0.069

Pre-orbital depth -0.290 0.161 0.232 -0.064

Cheek depth -0.238 -0.161 -0.089 0.004

Lower jaw length -0.226 -0.266* -0.202 -0.058

Head depth -0.224 -0.136 -0.076 0.016

Body depth -0.203 -0.197 -0.139 0.163

Snout to dorsal fin origin -0.231 -0.101 -0.040 -0.003

Snout to pelvic fin origin -0.228 0.008 0.067 -0.036

Dorsal fin base length -0.223 0.306* 0.357 -0.037

Anterior dorsal to anterior anal -0.192 0.161 0.208 -0.060

Anterior dorsal to posterior anal -0.205 0.215 0.264 -0.059

Posterior dorsal to anterior anal -0.218 0.058 0.115 -0.066

Posterior dorsal to posterior anal -0.199 0.101 0.150 -0.166

Posterior dorsal to ventral caudal -0.218 0.116 0.168 -0.092

Posterior anal to dorsal caudal -0.203 0.075 0.125 -0.099

Anterior dorsal fin to pelvic fin origin -0.110 0.29* 0.321 0.914*

Posterior dorsal to pelvic fin origin -0.023 -0.413* -0.390 0.194

Caudal peduncle length 0.005 -0.181 -0.173 0.082

Least caudal peduncle depth 0.006 -0.270* -0.259 0.109

(* Highest loadings for a particular variable)

Table 16: The principle component analysis PC1 (meristic) and their standardized scoring coefficients for D. altus and D. apogon

Variable Factor1 Factor2

Dorsal fin spines 0.10788 0.21423

Dorsal fin rays 0.07409 0.36346*

Anal fin rays 0.13903 0.31544*

Lateral line scale 0.20048 -0.03714

Cheek scale rows 0.17650 0.24824

Gill rakers on ceratobranchial 0.01713 -0.15386

Gill rakers on epibranchial -0.17292 0.12042

Teeth outer row of lower left jaw 0.17681 -0.04317

(*Highest scoring of a particular variable)

0.2 D. apogon

D.altus

)

a t

a 0.1

t e

m 0.0

m (

-0.1

R -0.2

H S

-0.3 -2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 PC1 (meristic data)

Figure 20: Plots of the sheared second principle components (morphological data) and the first factor score, first principle component (meristic data) for Diplotaxodon apogon and

Diplotaxodon altus sampled in Senga Bay and Domira Bay, Lake Malaŵi in 2012-2013

The minimum polygons sheared second principal components of the morphometric data plotted against the first principal components of the meristic data did not overlap (Fig.

20). The variables with the highest loadings on the PC1 based on the standardized scoring coefficients were Dorsal fin rays (0.36), anal fin rays (0.32) (Table 16). While for shape factors (SPC) the highest loadings were horizontal eye diameter and vertical eye diameter (-

0.31), dorsal fin base length (0.31), anterior dorsal fin origin to posterior anal fin (0.29) and posterior dorsal fin origin to posterior anal (-0.41)(Table 15).

Table 17: The Sheared principal components (PC2) and Unsheared Principle component

(PC2) variable loadings on size for D. altus and D. agenteus.

Sheared Unsheared Variable Size PC2 Size PC2

Standard length -0.192 0.137 0.146 -0.12057

Head length -0.241 -0.05 -0.04 0.027

Snout length -0.316 -0.00 0.013 -0.035

Postorbital head length -0.23 0.06 0.073 0.033

Horizontal eye diameter -0.162 -0.22 -0.216 0.084

Vertical eye diameter -0.157 -0.24 -0.235 0.099

Preorbital depth -0.290 0.18 0.195 -0.092

Cheek depth -0.28 -0.432* -0.419* 0.222 lower jaw length -0.28 -0.222 -0.209 0.031

Head depth -0.22 -0.108 -0.097 0.00

Body depth -0.209 -0.202 -0.192 0.177

Snout to dorsal-fin origin -0.248 -0.062 -0.051 0.036

Snout to pelvic-fin origin -0.220 -0.009 0.000 -0.041

Dorsal fin base length -0.171 0.295 0.302* -0.150

Anterior dorsal to anterior anal -0.164 0.129 0.137 -0.106

Anterior dorsal to posterior anal -0.170 0.193 0.201 -0.137

Posterior dorsal to anterior anal -0.202 0.017 0.026 -0.076

Posterior dorsal to posterior anal -0.192 0.071 0.080 -0.155

Posterior dorsal ventral caudal -0.178 0.196 0.204 -0.196

Posterior anal to dorsal caudal -0.182 0.147 0.155 -0.185

Anterior dorsal to pelvic-fin origin -0.131 0.51* 0.520* 0.818*

Posterior dorsal to pelvic-fin origin 0.035 -0.23 -0.236 0.135

Caudal peduncle length 0.040 0.021 0.018 0.119

Least caudal peduncle depth 0.028 -0.094 -0.095 0.118

( * Highest loadings for a particular variable)

Table 18: The principle component analysis PC1 (meristic) variables and their standardized scoring coefficients for D. altus and D. argenteus

Variable Factor1 Factor2

Dorsal fin spines 0.559* -0.067

Dorsal fin rays 0.692* 0.230

Anal fin spines 0.00000 0.00000

Anal fin rays 0.926* 0.026

Pelvic fin rays 0.00000 0.00000

Pectoral fin rays 0.496* 0.093

Lateral line scale 0.571* 0.309

Pored scales posterior lateral line -0.069 0.455*

Cheek scale rows 0.727* 0.230

Gill rakers on the ceratobranchial 0.581* -0.429

Gill raker on the epibranchial 0.064 -0.560

Teeth rows on lower left jaw 0.071 0.843*

Teeth rows on upper jaw -0.154 0.663*

Teeth rows on upper jaw -0.569* 0.311

(* Highest scoring for variable on factor 1 or2)

0.2 D. argenteus

D. altus

)

a t

a 0.1

r e

m 0.0

(

R -0.1

H S

-0.2 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 PC1 (meristic data)

Figure 21: Plots of the sheared second principle components (morphological data) and the first factor score, first principle component (meristic data) for Diplotaxodon argenteus and

Diplotaxodon altus.

The minimum polygons sheared second principal components of the morphometric data plotted against the first principal components of the meristic data did not overlap (Fig.

21). The variables with the highest loadings on the PC1 based on the standardized scoring coefficients were anal fin rays (0.93 ), lateral line scales (0.57), cheek scale rows (0.73), gill rakers on ceratobranchial (0.58), teeth on lower left jaw (-0.60) (Table 18). While for shape factors (SPC) the highest loadings were cheek depth (-0.43), anterior dorsal fin origin to posterior anal fin (0.51) (Table 17). 59

Table 19: The Sheared principal components (PC2) and Unsheared Principle component

(PC2) variable loadings on size for D. altus and D. maxillalongus.

Sheared Unsheared Variable Size PC-2 Size PC-2

Standard length -0.219 -0.065 -0.102 0.127

Head length -0.225 0.061 0.025 -0.116

Snout length -0.285 0.065 0.017 -0.121

Posterior head length -0.240 -0.057 -0.095 -0.116

Horizontal eye diameter -0.122 0.171 0.152 -0.217

Vertical eye diameter -0.121 0.163 0.145 -0.248

Preorbital depth -0.264 -0.018 -0.060 -0.078

Cheek depth -0.288 0.106 0.057 -0.085

Lower jaw length -0.253 0.198 0.156 -0.229

Head depth -0.186 0.130 0.098 -0.132

Body depth -0.198 0.141 0.107 -0.070

Snout to dorsal fin origin -0.233 0.057 0.019 -0.117

Snout to pelvic fin origin -0.216 0.034 -0.002 0.012

Dorsal fin base length -0.21 -0.161 -0.198 0.234

Anterior dorsal to anterior anal -0.193 -0.068 -0.100 0.094

Anterior dorsal posterior anal -0.211 -0.113 -0.148 0.177

Posterior dorsal to anterior anal -0.225 -0.003 -0.039 -0.014

Posterior dorsal to posterior anal -0.199 -0.089 -0.121 -0.104

Posterior dorsal to ventral caudal -0.224 -0.149 -0.187 0.167

Posterior anal to dorsal caudal -0.217 -0.101 -0.139 0.176

Anterior dorsal to pelvic fin origin2 -0.158 -0.347* -0.374 0.491*

Posterior dorsal to Pelvic fin origin -0.019 0.625* 0.614 0.453*

Caudal peduncle length -0.001 0.288* 0.286 0.221

Least caudal peduncle depth 0.012 0.379* 0.376 0.267*

(*Highest loading a particular variable)

Table 20: The principle component analysis PC1 (meristic) variables and their standardized scoring coefficients for D. altus and D. maxillalongus

Variable Factor1 Factor2

Dorsal fin spines 0.20953 0.25714*

Dorsal fin rays 0.16083 0.27067*

Anal fin rays 0.25199* 0.02965

Lateral line scale 0.26454* -0.06236

Pored scales posterior lateral line -0.15115 0.07178

Cheek scale rows 0.21121 -0.32300*

Gill rakers on the ceratobranchial 0.18699 0.17041

Gill raker on the epibranchial -0.08930 0.41716*

Teeth on outer row of lower left jaw 0.01525 -0.25771*

(* Highest scoring for variable on factor 1 or2)

0.3 maxillalongus

D. altus

)

a t

a 0.2

t e

m 0.1

m (

0.0

R -0.1

H S

-0.2 -2 -1 0 1 2 PC1 (meristic data)

Figure 22: Plots of the sheared second principle components (morphological data) and the first factor score, first principle component (meristic data) for Diplotaxodon maxillalongus and Diplotaxodon altus.

There was no overlap of polygons of sheared second principal components of the morphometric data plotted against the first principal components of the meristic data (Fig 22).

The variables with the highest loadings on the PC1 based on the standardized scoring coefficients were anal fin rays (0.25), lateral line scales (0.26) (Table 20). While for shape factors (SPC) the highest loadings were anterior dorsal fin origin to posterior anal fin (-0.35) and posterior dorsal fin origin to posterior anal (0.63), Caudal peduncle length (0.29), least caudal peduncle depth (0.38) (Table 19).

Table 21: The Sheared principal components (PC2) and Unsheared Principle component

(PC2) variable loadings on size for D. altus and D. greenwoodi.

Sheared Unsheared Variable Size PC2 Size PC2

Standard length -0.227 -0.007 -0.012 -0.047

Head length -0.217 -0.005 -0.010 -0.185

Snout length -0.283 -0.029 -0.036 -0.328

Postorbital head length -0.232 0.033 0.027 -0.215

Horizontal eye diameter -0.125 -0.032 -0.035 0.103

Vertical eye diameter -0.129 -0.018 -0.020 0.139

Pre-orbital depth -0.309 -0.093 -0.100 0.037

Cheek depth -0.217 -0.075 -0.080 0.468

Lower jaw length -0.208 -0.115 -0.120 -0.157

Head depth -0.216 -0.014 -0.019 0.058

Body depth -0.206 0.070 0.065 0.525

Snout to dorsal-fin origin -0.224 -0.028 -0.033 -0.069

Snout to pelvic-fin origin -0.231 -0.010 -0.016 -0.130

Dorsal fin base length -0.247 0.035 0.029 0.153

Anterior dorsal to anterior anal -0.205 -0.015 -0.019 0.069

Anterior dorsal to posterior anal -0.226 0.003 -0.002 0.093

Posterior dorsal to anterior anal -0.228 -0.030 -0.035 0.117

Posterior dorsal to posterior anal -0.218 -0.079 -0.084 -0.156

Posterior dorsal ventral caudal -0.223 -0.013 -0.018 -0.072

Posterior anal to dorsal caudal -0.206 -0.036 -0.041 -0.127

Anterior dorsal to pelvic-fin origin -0.102 0.953* 0.951* -0.003 63

Posterior dorsal to pelvic-fin origin -0.015 0.100 0.100 0.223

Caudal peduncle length -0.023 0.150* 0.149* -0.227

Least caudal peduncle depth -0.009 0.107 0.106 -0.195

(* Highest loadings for a particular variable for the sheared and unsheared)

Table 22: The principle component analysis PC1 (meristic) variables and their standardized scoring coefficients for D. altus and D. greenwoodi

Variable Factor1 Factor2

Dorsal-fin spines 0.6587 0.69862

Dorsal-fin rays 0.2578 0.82725*

Anal-fin rays 0.98624* -0.12032

Lateral line scale 0.52819 -0.81489*

Gill rakers on first epibranchial 0.85958 0.26948

Teeth on outer row of left lower jaw -0.98624* 0.12032

Teeth rows on upper jaw -0.98624* 0.12032

Teeth rows on lower jaw -0.98624* 0.12032

(* Highest scoring for variable on factor 1 or2)

D. altus

0.1 D. greenwoodi

)

c i

r 0.0

p r

o -0.1

(

D -0.2

H S

-0.3 -2.0 -1.5 -1.0 -0.5 0.0 0.5 PC1 (meristic data)

Figure 23: Plots of the sheared second principle components (morphological data) and the first factor score, first principle component (meristic data) for Diplotaxodon altus and

Diplotaxodon greenwoodi.

The plot of D. altus and D. greenwoodi indicated that there was no overlap of polygons of sheared second principal components of the morphometric data plotted against the first principal components of the meristic data (Fig. 23).The variables with the highest loadings on the PC1 based on the standardized scoring coefficients were anal-fin rays (0.99), teeth in outer row of left lower jaw (-0.99), teeth rows on upper jaw (-0.99) and teeth rows on lower jaw (0.99) (Table 22).

D. altus

0.3 D. limnothrissa

)

c 0.2

m o

h 0.1

(

2 0.0

D R

H -0.1 S

-0.2 -3 -2 -1 0 1 2 PC1 (meristic data)

Figure 24: Plots of the sheared second principle components (morphological data) and the first factor score, first principle component (meristic data) for Diplotaxodon altus and

Diplotaxodon limnothrissa

8.0.0 Diplotaxodon maxillalongus n. sp., n. nov (nova species, novem nomen) (Fig. 18)

Diplotaxodon sp. ‘maxillalongus’.

Holotype (1) PSU 12499: Collected from trawl net at a depth below 110m, Northeast of

Domira Bay, Lake Malaŵi 2012. Collected by T. Phiri

Paratype (4) PSU12500, LUANARB01 (10): Collected from trawl net at a depth below

110m, Northeast of Domira Bay, Lake Malaŵi 2012. Collected by T. Phiri.

Diagnosis. The snout length (30-37% HL) distinguishes it from D. apogon and D. aeneus (26.1-30.5%, and 27.8-29.9% HL respectively). Distinguishes from D. greenwoodi

Stauffer & McKaye, 1986 by having a relatively longer snout to dorsal fin origin length (41-

43% versus 38.3-40.4% HL), shorter lower jaw length and head depth (26-32% and 60-73%

HL vs 46-51.9% and 82.4-87% of HL respectively). It has fewer gill rakers on the outer arch of the ceretobranchial (16-21) than those of D. limnothrissa and D. argenteus which have of

21-27 and 20-26 respectively. More dorsal-fin spines than D. apogon (12-14 versus 14-16).

More lateral line scales than D. ecclesi (34-35 versus 32). Less ceratobranchial gill rakers than D. macrops (17-19 versus 20-25).

Description. Morphometric ratios and meristic data in Table 23. Deep bodied but laterally compressed. Eye diameter shorter than snout length. Head concave just above eye.

Jaws elongated and prognathous; frontal lower teeth visible. Premaxillary with beak. Longest ray on pectoral fin not to first anal-fin spine. The pelvic fin of female short, not to vent.

Longest ray of anal fin and dorsal fin to half-length of caudal peduncle. Caudal fin emarginate.

Small ctenoid scales. Lateral-line scales between 26-34 and the lower lateral line short but straight. Two series of scales between upper and lower lateral lines at anterior of lower lateral line. One scale row posterior between upper and lower lateral lines. One scale series between lateral line and posterior of dorsal fin. Cheek with 2 rows of scales, smaller dorsal

anteriorly. 6 gill rakers on outer arch of epibranchial and 16-21 outer arch of ceratobranchial.

Gill rakers on the ceratobranchial longer.

Teeth fairly larger and curved inwardly (Fig. 26). Teeth in two series on both upper and lower jaws. Outer teeth larger than inner teeth. Mature male fish dark grey dorsally and lighter grey ventrally. Mature females grey dorsally and white ventrally. Has no bars, stripes, saddles or blotches absent.

Distribution: Diplotaxodon maxillalongus is found in offshore habitat. It is rare compared with D, limnothrissa, D. macrops and D. argenteus. It is common in trawl nets at depths below 80m. Samples for the description were collected northeast of Domira Bay and southeast of Senga Bay, Lake Malawi.

Etymology.The specific name ‗maxillalongus‘ is derived from a Latin words maxilla which means upper jaw and longus which means long, in reference to the long upper jaw bone.

Figure 25: A female Diplotaxodon maxillalongus from collected from Senga Bay, northeast of Chipoka. (Photo: by Evance Samikwa 2013).

Figure 26: Part of the mouth showing the jaw arrangement and the teeth structure on the lower jaw

8.1.0 Results

Table 23: Morphometric and meristic values of type series of Diplotaxodon maxillalongus

(n= 18) with mean, standard deviation and range of the population including the holotye sampled from Senga Bay and Domira Bay in 2012-2013

Variable Holotype Mean SD Range

Standard length, mm 182.99 122.49 18.49 105.4-167.9

Head length, mm 71.47 45.41 7.66 38.7-68

Percent of standard length

Body depth 59.55 31.50 2.79 26-35

Snout to dorsal-fin origin 78.11 40.00 2.99 34-45

Snout to pelvic-fin origin 80.01 41.44 1.92 38-44

Dorsal fin base length 85.2 47.06 2.07 43-51

Anterior dorsal to anterior anal 79.19 43.61 1.42 41-46

Anterior dorsal to posterior anal 95.16 52.28 1.60 50-55

Posterior dorsal to anterior anal 50.92 26.61 1.65 23-29

Posterior dorsal to posterior anal 29.69 16.17 0.99 14-18

Posterior dorsal ventral caudal 38.03 22.28 1.07 21-25

Posterior anal to dorsal caudal 38.12 22.28 1.02 21-25

Anterior dorsal to pelvic-fin origin 58.63 49.28 1.84 46-54

Posterior dorsal to pelvic-fin origin 90.29 30.06 4.45 21-38 caudal peduncle length 29.02 16.83 2.77 11-21

Least caudal peduncle depth 22.33 12.11 1.68 8-14

Percent of head length

Snout length 26.94 32.56 1.54 30-37

Postorbital head length 23.59 36.17 1.82 33-39

Horizontal eye diameter 17.72 30.06 2.55 25-34

Vertical eye diameter 17.72 30.50 2.96 25-35

Pre-orbital depth 13.4 18.67 1.28 16-21

Cheek depth 11.13 14.61 1.61 12-18 lower jaw length 23.28 28.56 1.58 26-32

Head depth 44.26 65.33 3.79 60-73

Counts Mode Frequency % Range

Dorsal-fin spines 15 14 42.86 13-16

Dorsal-fin rays 8 11 38.10 8-13 anal-fin spines 3 3 100 3-3

Anal-fin rays 10 10 66.67 9-11

Pelvic-fin rays 5 5 100 5-5

Pectoral-fin rays 13 13 95.24 11-13

Lateral line scale 33 32 28.57 26-34

Pored scale posterior to lateral line 1 1 76.19 1-2

Scale rows on cheek 3 2 85.71 2-3

Gill rakers on first epibranchial 6 6 71.43 4-6

Gill rakers on first ceratobranchial 18 20 38.10 16-21

Teeth in outer row of left lower jaw 33 32 52.38 32-33

Teeth rows on upper jaw 2 2 100 2-2

Teeth rows on lower jaw 2 2 100 2-2

0.2 D. argenteus

) D. maxillalongus

c i

r 0.1

p r

o 0.0

(

D -0.1

H S

-0.2 -3 -2 -1 0 1 2 PC1 (meristic data)

Figure 27: Plots of the sheared second principle components (morphological data) and the first factor score, first principle component (meristic data) for Diplotaxodon argenteus and

Diplotaxodon maxillalongus

The plot of D. argenteus and D. maxillalongus had no overlap of polygons of sheared second principal components of the morphometric data plotted against the first principal components of the meristic data (Fig. 27).

Table 24: The Sheared principal components (PC2) and Unsheared Principle component

(PC2) variable loadings on size for D. maxillalongus and D. greenwoodi

Sheared Unsheared Variable Size PC-2 Size PC-2

Standard length -0.211 0.153 0.129 -0.149

Head length -0.228 -0.062 -0.090 0.118

Snout length -0.284 -0.012 -0.048 0.104

Postorbital head length -0.243 -0.069 -0.097 0.047

Horizontal eye diameter -0.120 -0.135 -0.150 0.32*

Vertical eye diameter -0.114 -0.174 -0.189 0.33*

Pre-orbital depth -0.231 -0.095 -0.120 -0.010

Cheek depth -0.333 -0.177 -0.215 -0.033

Lower jaw length -0.281 -0.195 -0.229 0.183

Head depth -0.164 -0.082 -0.104 0.148

Body depth -0.190 -0.145 -0.169 0.116

Snout to dorsal fin origin -0.238 -0.095 -0.123 0.070

Snout to pelvic fin origin -0.204 0.074 0.049 0.010

Dorsal fin base length -0.196 0.22* 0.198 -0.26*

Anterior dorsal to anterior analaa -0.184 0.104 0.083 -0.142

Anterior dorsal to posterior anal -0.199 0.179 0.157 -0.21*

Posterior dorsal to anterior anal -0.221 0.022 -0.005 -0.041

Posterior dorsal to posterior anal -0.185 0.013 -0.010 -0.061

Posterior dorsal to ventral caudal -0.223 0.21* 0.184 -0.27*

Posterior anal to dorsal caudal -0.223 0.21* 0.183 -0.2&*

Anterior dorsal fin to pelvic fin origin -0.190 0.166 0.144 -0.177

Posterior dorsal fin to pelvic fin origin -0.019 0.49* 0.489 0.36*

Caudal peduncle length 0.015 0.44* 0.439 0.37*

Least caudal peduncle depth 0.027 0.38* 0.380 0.27*

(* Highest loadings for a particular variable for sheared and unsheared)

Table 25: The principle component analysis PC1 (meristic) variables and their standardized scoring coefficients for D. maxillalongus and D. apogon

Variable Factor1 Factor2

Dorsal fin spines -0.063 0.291*

Dorsal fin rays -0.050 0.230*

Anal fin rays -0.023 0.266*

Lateral line scale 0.083 0.262*

Pored scales posterior lateral line -0.053 -0.142

Cheek scale 0.211* 0.030

Gill rakers on the ceratobranchial 0.017 0.246*

Gill raker on the epibranchial -0.212* 0.068

Teeth in outer row of left lower jaw 0.205* -0.080

Teeth rows on upper jaw 0.503* 0.106

(* Highest scoring for variable on factor 1 or2)

0.3 D. maxillalongus

D. greenwoodi

)

t a

d 0.2

o h

p 0.1

(

C P

0.0

H S

-0.1

-1 0 1 2 3 4 PC1 (meristic data)

Figure 28: Plots of the sheared second principle components (morphological data) and the first factor score, first principle component (meristic data) for Diplotaxodon maxillalongus and Diplotaxodon greenwoodi.

The plot of D. greenwoodi and D. maxillalongus did not overlap (Fig 28). The variables with the highest loadings on the PC1 based on the standardized scoring coefficients were Scale rows on the cheek (0.21) gill rakers on epibranchial (-0.21), gill raker on ceratobranchial (-

0.12), teeth on outer row of lower left jaw and teeth rows on upper jaw (0.50) for factor 1

(Table 25). While for shape factors (SPC) the highest loadings were dorsal fin base length

(0.21), Posterior dorsal ventral caudal (0.21), Posterior anal to dorsal caudal (0.21), posterior

dorsal to posterior anal (0.49), caudal peduncle length (0.44) and least caudal peduncle depth

(0.38) for the sheared (Table 24).

Table 26: The principle component analysis PC1 (meristic) and their standardized scoring coefficients for D. maxillalongus and D. limnothrissa

Sheared Unsheared Variable Size PC-2 Size PC-2

Standard length -0.18 0.21 0.20 0.02

Head length -0.23 -0.09 -0.11 0.10

Snout length -0.29 -0.03 -0.05 0.06

Post orbital head length -0.21 0.00 -0.01 0.16

Horizontal eye diameter -0.19 -0.4* -0.38 0.17

Vertical eye diameter -0.19 -0.4* -0.41 0.16

Pre-orbital depth -0.23 0.02 0.00 0.3*

Cheek depth -0.32 0.00 -0.02 -0.17

Lower jaw length -0.31 -0.3* -0.28 0.02

Head depth -0.20 -0.13 -0.15 -0.04

Body depth -0.25 -0.18 -0.20 -0.3*

Snout to dorsal fin origin -0.25 -0.09 -0.11 0.08

Snout to pelvic fin origin -0.21 0.05 0.03 0.07

Dorsal fin base length -0.15 0.3* 0.33 -0.05

Anterior dorsal to anterior anal -0.18 0.19 0.17 -0.10

Anterior dorsal to posterior anal -0.17 0.27* 0.26 -0.05

Posterior dorsal to anterior anal -0.21 0.08 0.07 -0.18

Posterior dorsal to posterior anal -0.19 0.01 0.00 -0.13

Posterior dorsal to ventral caudal -0.17 0.3* 0.26 0.03

Posterior anal to dorsal caudal -0.17 0.3* 0.28 0.02

Anterior dorsal to pelvic fin origin -0.18 0.24 0.23 -0.11

Posterior dorsal to pelvic fin origin 0.00 0.05 0.05 0.6*

Caudal peduncle length 0.01 0.3* 0.25 0.4*

Least caudal peduncle depth 0.02 0.11 0.11 0.4*

(* Highest loadings for a particular variable)

Table 27: The principle component analysis PC1 (meristic) variables and their standardized scoring coefficients for D. maxillalongus and D. limnothrissa

Variable Factor1 Factor2

Dorsal fin spines 0.225* -0.108

Dorsal fin rays 0.207* -0.021

Anal fin spines 0.000 0.000

Anal fin rays 0.094 -0.294*

Pelvic fin rays 0.000 0.000

Pectoral fin rays -0.034 0.181

Lateral line scale 0.194 -0.122

Pored scales posterior lateral line 0.031 0.253*

Cheek scale rows -0.114 -0.147

Gills rakers on the ceratobranchial 0.188 -0.240

Gill rakers on the epibranchial 0.211* 0.017

Teeth on outer row lower left jaw 0.162 0.377*

Teeth rows on upper jaw 0.000 0.000

Teeth rows on lower jaw 0.091 0.463*

(* Highest scoring for variable on factor 1 or2) 77

0.2 D. maxillalongus

D. limnothrissa

)

a d

0.1

h p

r 0.0

(

C P

-0.1

H S

-0.2 -2 -1 0 1 2 PC1 (meristic data)

Figure 29: Plots of the sheared second principle components (morphological data) and the first factor score, first principle component (meristic data) for Diplotaxodon maxillalongus and Diplotaxodon limnothrissa.

The two clusters were significantly different along both axes, the first principal component PC1 (F1, 39=41.91; P <0.001) meristics (axis) and along the Sheared Second

Principal Component PC2 (F1,39 =57.09; P <0.001) morphometric (axis). The MANOVA test based on ―Hotelling-Lawley‖ indicated that the clusters were significantly different (P

<0.001).

The plot of D. limnothrissa and D. maxillalongus had a slight overlap of polygons of sheared second principal components of the morphometric data plotted against the first

principal components of the meristic data (Fig. 29), but were significantly different (<0.05) along the meristic data.

The variables with the highest loadings on the PC1 based on the standardized scoring coefficients were Dorsal fin spines (0. 23), anal fin rays (0.21) and gill rakers on epibranchial

(-0.21) for factor 1(Table 27). While for shape factors (SPC) the highest loadings were eye diameters (0.4), lower jaw length (0.3), Posterior anal to ventral caudal (0.3), posterior anal to dorsal caudal (0.3) and caudal peduncle length (0.44) for the sheared (Table 26).

Table 28: The Sheared principal components (PC2) and Unsheared Principle component

(PC2) variable loadings on size for D. maxillalongus and D. apogon

Sheared Unsheared Variable size PC-2 Size PC-2

Standard length -0.21 0.18 0.20 0.10

Head length -0.23 -0.13 -0.10 0.06

Snout length -0.28 -0.04 -0.01 0.06

Postorbital head length -0.24 -0.02 0.01 0.00

Horizontal eye diameter -0.16 -0.44* -0.42 0.25

Vertical eye diameter -0.15 -0.47* -0.45 0.21

Pre-orbital depth -0.23 0.00 0.03 0.18

Cheek depth -0.33 -0.03 0.01 -0.33*

Lower jaw length -0.28 -0.18 -0.15 -0.02

Head depth -0.18 -0.20 -0.18 -0.13

Body depth -0.19 -0.21 -0.18 -0.17

Snout to dorsal fin origin -0.24 -0.11 -0.09 0.03

Snout to pelvic fin origin -0.21 0.02 0.05 0.06

Dorsal fin base length -0.19 0.33* 0.35 0.06

Anterior dorsal to anterior anal -0.18 0.20 0.22 -0.02

Anterior dorsal to posterior anal -0.19 0.26 0.29 0.02

Posterior dorsal to anterior anal -0.21 0.07 0.09 -0.17

Posterior dorsal to posterior anal -0.18 0.03 0.05 -0.19

Posterior dorsal to ventral caudal -0.22 0.24 0.26 0.15

Posterior anal to dorsal caudal -0.22 0.25 0.28 0.14

Anterior dorsal to pelvic fin origin -0.18 0.20 0.23 -0.02

Posterior dorsal to pelvic fin origin -0.02 0.10 0.10 0.53*

Caudal peduncle length 0.03 0.00 0.00 0.45*

Least caudal peduncle depth 0.03 0.03 0.03 0.30*

(* Highest loadings for a particular variable)

Table 29: The principle component analysis PC1 (meristic) variables and their standardized scoring coefficients for D. maxillalongus and D. apogon.

Variable Factor1 Factor2 Factor3 Dorsal fin spines 0.29* 0.14 0.02

Dorsal fin rays 0.30* -0.15 0.25*

Anal fin spines 0.00 0.00 0.00

Anal fin rays 0.22 -0.02 -0.06

Pelvic fin rays 0.00 0.00 0.00

Pectoral fin rays -0.10 0.21 0.49

Lateral line scales 0.21 0.30 -0.10

Pored scales posterior lateral line -0.05 -0.31 -0.33*

Cheek scale rows -0.12 0.28 -0.42*

Gills rakers on the ceratobranchial 0.21 0.14 -0.04

Gill rakers on the epibranchial 0.18 -0.31 -0.04

Pored scales posterior lateral line -0.13 -0.08 0.38* Teeth rows upper jaw 0.00 0.00 0.00

Teeth rows on lower jaw 0.00 0.00 0.00

(* Highest scoring for variable on factor 1 or2)

0.20 D. apogon D. maxillalongus

0.15

)

a d

0.10

e m

o 0.05

m (

0.00

D -0.05

H S -0.10

-0.15 -2 -1 0 1 2 Factor1 (meristic Data)

Figure 30: Plots of the sheared second principle components (morphological data) and the first factor score, first principle component (meristic data) for Diplotaxodon apogon and

Diplotaxodon maxillalongus.

The two clusters were significantly different along the Sheared Second Principal

Component morphometric (axis) and along the first Principal Component PC1 (meristics

(axis) . The MANOVA test based on ―Hotelling-Lawley‖ indicated that the clusters were significantly different (P < 0.05).

The plot of D. greenwoodi and D. maxillalongus had an overlap of polygons of sheared second principal components of the morphometric data plotted against the first principal components of the meristic data (Fig. 30). The variables with the highest loadings on the PC1 based on the standardized scoring coefficients were dorsal fin spines (0.29) and anal fin rays (0.3) for factor 1 (Table 29). While for shape factors (SPC) the highest loadings were horizontal and vertical eye diameters (-0.44 and 0.47 respectively), dorsal fin base length (0.33) for the sheared (Table 28).

9.0.0 Discussion

Extraordinary species diversity of Lake Malaŵi cichlids does not translate into high genetic diversity. Rapid radiation of the Haplochromine and low genetic diversity poses a big challenge for systematists attempting to delimit species (Stauffer 2001). The discovery of external characters that can be used to delimit species is critical for determining life history, behavior, distribution, and reproductive biology which are needed to devise effective management strategy (Stauffer 2007). For the purpose of this study, I recognized species as individuals in ontological sense as explained by Ghiselin (1974, 1997). Species exist because they evolved in a speciation event (Mayden 1999, Stauffer 2001). In such context it makes more sense to develop fisheries management strategies to increase yield, prevent extinction, and address questions of native and exotic species (Stauffer et al. 2007). Conversely it does not make sense to consider species as categories where species are constructs of the human mind. It is impossible to manage a construct of human mind where by definition cannot evolve or become extinct (Stauffer 2001). In this regard, I view species in a broader philosophical framework of the Evolutionary Species Concept (ESP) as proposed by Simpson

(1951). The ESC is recognized in diagnosing the species of the genus Diplotaxodon because it is the only species concept that provide theoretical basis for describing all species (George et al. 2005, Stauffer et al.1997). However the ESC is non-operational and it is not practical to use (George et al. 2005); other criteria associated with surrogate species concepts (biological and morphological species concepts) were used with their operational definitions of species to distinguish species taxa (Stauffer et al. 2001, Stauffer et al. 1997). Biological Species concept (BSP) was considered because male color (though morphological, female fish use color in reproductive selection) was used as an exhibition of the presence of different species in the sample collection. Although the BSC possess both ecological and genetic components, the definition does not emphasize morphological difference; it only provide an operational method for identifying species through reproductive isolation as such the method is difficult 83

to put into practice (George et al. 2005). Species traditionally have been described and identified into discrete groups on the basis of morphological criteria; it was practical to regard species based on morphologically distinct individuals and it conveyed a criterion pertinent to the Morphological Species Concept (Kocher 2004).

Unlike in Mbuna (rock dwelling) and many other Lake Malaŵi cichlids,

Diplotaxodon apart from being considered monochromatic the male nuptial pattern differences appear to be decoupled from phylogenetic and selective influences on the non- territorial body pattern (Genner et al. 2007). It was therefore required of this study to thoroughly analyze morphological differences and just like Turner and Stauffer (1998), there was no unambiguous character state for these species. Morphological characters have been commonly used in fisheries biology to measure discreteness and relationships among various taxonomic categories (Turan 1999). Morphology has an significant role in the study of systematics and evolution of organism; for a long time meristic and univariate morphometric analysis have been used to delimit species, in some instances species were described using one or two specimen (Stauffer 2001). There was a distinct morphometric difference, and meristic frequency counts differences for the diagnosed species. It was imperatively necessary to use mature fish in this study the presence of male color was used as evidence of the existence of species (Turner and Stauffer 1998). The male breeding color cannot always be a clear cut basis for diagnosing species in the genus Diplotaxodon. Turner and Stauffer

(1998) noted that male bleeding color for D. ecclesi and D. macrops were similar but had morphologic and meristic differences.

When using principle component analysis, shape and size were the major input to consider variation of populations. Sundberg (1989) noted that shape as well as size diverges for subpopulation during natural selection. And further Sundberg (1989) explains that size is equally an important element and when standardizing it should not be removed, considering situations of sexual dimorphism in size may confound the analysis. Somers (1989) argued 84

that size is often evaluated within a bivariate framework with no concomitant change in shape. And this bivariate conceptualization of size and shape has been extrapolated to a multivariate model summarized by the principal component analysis (Somers (1989), where first component anywhere in the component analysis is identified with size (Bookstein 1989).

Size in this study was only considered when selecting mature fish for grouping.

The male breeding colors for D. macrops were somehow similar to that of D. altus previously known with a working name ‗deep‘. However D. macrops is known to be a smaller species, not known to be larger than 120mm SL (Turner and Stauffer, 1998) and D. altus has a deeper body than D. macrops. With such notable characteristics it was very compelling to test the hypothesis if these were indeed different species. The morphological and meristic examination clearly showed that these are different species. The maximum standard length for D. altus was 192mm which by size category of the species in this genus cannot be regarded as a small species. When D. altus was compared with other described species there were significant differences. The plots for the sheared second principal components of the morphometric data plotted against the first principal components of the meristic data showed separate cluster and the minimum polygons did not overlap in all the plots, implying that they are not conspecific.

There had been some assumptions from that D. maxillalongus might be conspecific to

D. greenwoodi; however the findings of this study are proving otherwise, the increased gape inclination clearly distinguished D. greenwoodi from D. maxillalongus. Elongated distance between tip of snout to just above the eye (maxilla bone) of D. maxillalongus distinguishes it from D. greenwoodi. The analysis of sheared principal component of the morphometric and meristic data support the argument that the species were heterospecific. The plot for Principle

Component (PC1), meristic data and Shear Principle Component (PC2) morphomentric data showed that that they were undoubtedly different clusters (Fig 29). When D. maxillalongus

was compared with other described species, there were no overlaps for the plot with all other species apart from with D. limnothrissa (Fig 29) and D. apogon (Fig 30). An ANOVA suggested that the minimum polygon clusters for the sheared principal component axis of the morphometric data and the first principal component axis of the meristic data were significantly different along the axis and were independent of the other. Similarly the Duncan

Multiple Range Test (DMRT) determined that clusters were significantly different.

10.0.0 Conclusion

There had been confusion where several cheironyms were believed to have been given to a single species. It is almost impossible to work with undescribed fish species from all types fishery for scientific information retrieval and general management of a fishery. A number of cheironyms were given to unnoticeable and undescribed species of the genus

Diplotaxodon by several scientists. It is not very unlikely that most of these names were redundantly referring to the same species or same name referring to different species. In absence of a species description and working with cheironym was extremely difficult to retrieve reliable and scientific information. Despite the fact that there may be large number of undescribed species in the genus Diplotaxodon, it has been extremely confusing to work with undescribed coupled with lack of reference material for the same.

Investigations of this study resulted in describing new species, Diplotaxodon altus and

Diplotaxodon maxillalongus. The described species add to the other valid seven described species. The new described species in this study are considered valid on the basis of evolutionary species concept.

The high number of cheironyms available in literature (Table 7) suggest the possible number of species that may still exist in Lake Malaŵi undescribed. It was noted in this study that some of the cheironym were conspecifics of other described species i.e. there was no significant difference between D. limnothrissa and D. ‗white top‘, they were therefore treated 86

as one species. In a similar situation it is also very possible that most of these working names might be referring to a particular existing species. I recommend that another study be conducted and sample more parts of the lake to describe some more species and investigate thoroughly on the biology of these species.

CHAPTER 3

11.0.0 Dichotomous key for Diplotaxodon

1. a) Big eye present, normally silvery color, elongated body, ...... 2

b) Big eye present, normally silvery color, deep body……….……...………...………6

2. a) Eye diameter shorter than snout length………...….………………………………..3

b) Eye diameter greater than snout length…………...…...……………………………5

3. a) Smaller head, small mouth, small closely set of teeth, lack of beak like

premaxillary, gill raker on ceratobranchial (20-26)……………………….limnothrissa

b) Less slender………….……….…………………………………………………….4

4. a) Ripe males are silvery with dusky dorsum and head, Black eye, snout, dorsal, anal,

caudal and pelvic fins, 1-2 large yellow egg spot on anal fin, gill rakers on

ceratobranchial (21-27 )…….……………………………..……………….…argenteus

b) Longer lower jaw……………………………...……………………………………5

5. a) Ripe male dark grey with white margin to the dorsal fin and bronze sheen, lower

jaw slightly protruding, pre-maxillary very slightly protruded, caudal peduncle depth

is 11% of SL, Body depth 32% of SL, dorsal fin 15…………...………………ecclesi

b) Not slender …………………………………………………………………………6

6. a) Increased gape inclination (57-66%), fourth row of teeth on the upper jaw,

compressed body, slight ventral protrusion at sympsis of dentries, 10-11 segmented

anal rays. 34 pored lateral line scales, eye diameter shorter than snout

length...…………………………………………………………….……….greenwoodi

b) Less gape inclination……………………………..…………………………………7

7. a) Long snout length ( 30-37% of head length), eye diameter shorter than the snout

length, 13-16 dorsal fin spines ,2-3 egg spots, 16-21gill rakers on ceratobranchial

………………………………….…………………………………..…maxillalongus

b) Eye diameter greater than snout length……………………………………………8

8. a) Smaller species, scales 33-35 lateral line scales, short lower jaw (37-41% HL),

deep but narrower body, shorter pre-dorsal length (34-38% SL), a yellow egg spot on

anal fin, 14-16 dorsal spines………….………………………………………..macrops

b) Moderately wider body, relatively longer lower jaw………..….………………….9

9. a) Larger pre-dorsal length, lower jaw protruding, relatevily longer lower jaw length

(38-43%HL), body depth (34-37% SL), Pelvic fin long usually reaching vent and in

ripe males beyond, pectoral …………………………………..……………….. aeneus

b) Notable belly………………………………..……………………………………..10

10. a) Relatively with large eyes, lower jaw protrude, ripe males with pale silvery flanks,

12-14 total dorsal spine, 31-34 lateral line scales, 16-20 ceratobranchial gill-rakers,

42-46% HL lower jaw length, body depth 32-37% of standard length….……apogon

b) Shorter lower jaw length (31-34% of Head Length), 14-16 dorsal fin spines

17-19 gill rakers on ceratobranchial, 31-41% SL body depth, short snout length, 34-

35 lateral line scales………………………………………………………..……. altus

Table 30: The adopted scientific classification (Linnaeus hierarchy) to which Diplotaxodon spp. were described for the binomial nomenclature.

Kingdom: Animalia

Phylum: Chordata

Subphylum: Vertebrata

Superclass: Gnathostomata

Class: Actinopterygii

Order: Perciformes

Family: Cichlidae

Subfamily: Psuedocrenilabrinae

Tribe: Haplochromini

Genus: Diplotaxodon Trewavas 1935

13.0.0 Remarks

Two species (D.greenwoodi and D. ecclesi) were redescribed because of some limitations in the original decription. The species description of D. greenwoodi was revised on the explanation that the distribution records given by Eccles &Trewavas (1989) were possibly not reliable, argued that the species might have been confused with D. macrops and

D. apogon (Turner & Stauffer 1998). The male breeding color of D. ecclesi is very similar to that of D. macrops and can easily be confused but D. ecclesi is more slender (Turner &

Stauffer 1998). The presence of eggs in stomach of D. greenwoodi suggested that it is a paedophage. It was found with eggs in the stomach from a deep water trawl where numerous ripe male and female Lethrinops gossei were present suggesting that the trawl was made in the breeding arena where a paedophage would be expected (Stauffer &McKaye, 1986). I was unable to get D. altus samples from the commercial trawls and semi commercial trawl which operated during the day even after six months of sampling. I managed to get sample for the same from small scale fishery which operated at night and uses light to attract fish, suggesting that D. altus move up the water column at night. I noted the presence of juvenile fishes in the mouth (Fig 31) of D. maxillalongus, D. apogon and D. greenwoodi, supporting the fact that Diplotaxodon spp. are piscivorous.

Figure 31: Diplotaxodon spp. with a juvenile fish in the mouth.

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