Phylogenetic analysis of (Perciformes: Cichlidae) endemic to and validation of the Paracyprichromis

Tetsumi Takahashi

Lake Biwa Museum, 1091 Oroshimo, Kusatsu, Shiga 525-0001, Japan (e-mail: [email protected])

Received: January 7, 2003 / Revised: July 25, 2003 / Accepted: August 1, 2003

Abstract The phylogenetic relationships among two Paracyprichromis and five species, Ichthyological included in the Tanganyikan tribe Cyprichromini, were investigated using morphological fea­ Research tures. The previously proposed diagnostic characters of Paracyprichromis are not synapomorphies, because the nonelongated swim bladder is plesiomorphic, the numbers of dorsal and anal fin rays and ©The Ichthyological Society of Japan 2004 scales on longitudinal line and around the caudal peduncle overlap with those of Cyprichromis, and Ichthyol Res (2004) 51: 1-4 these counts and number of vertebrae are all included within the ranges of other Tanganyikan . The monophyly of Paracyprichromis is supported by a unique condition of infraorbitals to this genus. DOI 10.1007/s10228-003-0183-5 Additionally, the monophyly of Cyprichromis was reconfirmed by one of the previously proposed diagnostic characters, the presence of an elongated swim bladder.

Key words Cyprichromini • Paracyprichromis • Synapomorphy • Lake Tanganyika

he cichlid tribe Cyprichromini Poll, 1986 includes two This study attempts to resolve the phylogenetic relation­ T endemic genera in Lake Tanganyika, Cyprichromis ships of the members of the tribe Cyprichromini, on the Scheuermann, 1977 and Paracyprichromis Poll, 1986, with basis of internal and external morphological characters, and four and two valid species, respectively, of small, stream­ to identify a derived character attesting to the monophyly of lined maternal mouth brooders (Konings, 1998). The genus Paracyprichromis. Cyprichromis was described by Scheuermann (1977) for Limnochromis leptosoma (Boulenger, 1898) as having a slender body (body depth 1/4 to 1/4.5 times lower than Materials and Methods standard length), large numbers of soft rays in the dorsal and anal fins (11-18 and 8-12, respectively), large numbers All six valid species of the tribe Cyprichromini, plus an of gill rakers (20-24) and scales on the longitudinal line (35­ undescribed species (Cyprichromis sp., sensu Takahashi et 71), and a highly protrusile upper jaw. Five additional spe­ al., 2002), as well as representatives of all other Tanganyikan cies have been included in Cyprichromis: Cyprichromis cichlid tribes, were examined. Specimens were identified by microlepidotus (Poll, 1956) and Cyprichromis nigripinnis comparison of the morphological features with the descrip­ (Boulenger, 1901) (both formerly in Limnochromis), tions of Takahashi et al. (2002) for Cyprichromis and Cyprichromis brieni Poll, 1981, Cyprichromis pavo Buscher, Poll (1981) for Paracyprichromis. Based on their molecular 1994, and Cyprichromis zonatus Takahashi, Hori and phylogenetic analysis, Sturmbauer and Meyer (1993) Nakaya, 2002. tentatively identified a sister-group relationship between Poll (1981) noted that among Tanganyikan cichlids Cyprichromini and Ectodini, but their evidence was weak, and C. microlepidotus exclusively the bootstrap value supporting the monophyly of those had more abdominal vertebrae than caudal vertebrae and tribes being only 68%. Therefore, a variety of Tanganyikan an elongated swim bladder, extending posteriorly beyond cichlid taxa were examined and included in the phyloge­ the anal fin origin. Subsequently, Poll (1986) created a new netic analysis as a single, composite outgroup taxon. One to genus Paracyprichromis for C. nigripinnis and C. brieni three specimens of each species were dissected, with the based on characters contrasting with those of Cyprichromis, exception of C. pavo. In undissected specimens, all charac­ including fewer abdominal vertebrae than caudal vertebrae, ters were determined, character 1 (type of infraorbitals) no elongation of the swim bladder, and a few additional being determined through the skin, characters 2 (number of characters. Neither the monophyly of Paracyprichromis nor vertebrae), 3 (length of abdominal cavity), and 6 (number of the status of these characters was tested cladistically. In fact, procurrent rays) being discernible from radiographs, and Konings (1998) doubted the validity of Paracyprichromis, character 4 (number of scale rows) being external features. but gave no reasons. Caudal fin coloration (character 5) was observed by 2 T. Takahashi

SCUBA-assisted divers in about 10 m depth at Kasenga (for Table 1. Character states of Cyprichromini and composite outgroup C. leptosoma, C. zonatus, Cyprichromis sp., and Para- for cladistic analysis cyprichromis brieni) or noted from photographs stored in the HUMZ photo library (outgroup taxa). Coloration of C. Taxon 1 2 3 4 5 6 microlepidotus follows Buscher (1994), C. pavo follows Cyprichromis leptosoma 0 1 1 1 1 1 Buscher (1994) and M. Hori (personal communication), and Cyprichromis microlepidotus 0 1 1 1 1 1 P. nigripinnis follows M. Hori (personal communication). Cyprichromis pavo 0 1 1 1 0 1 Methods for specimen dissections, as well as osteological Cyprichromis zonatus 0 1 1 1 0 1 terminology, meristic characters, and cladistic analysis, fol­ Cyprichromis sp. 0 1 1 1 1 1 low Takahashi (2002). Standard length is abbreviated as SL. Paracyprichromis brieni 1 0 0 0 0 0 Specimens examined are listed following the tribal Paracyprichromis nigripinnis 1 0 0 0 0 0 classification of Takahashi (2003a). All specimens were col­ Composite outgroup 0 0&1 0 0&1 0 0&1 lected from Lake Tanganyika, Africa. Asterisks after indi­ vidual registration numbers indicate dissected specimens. Institutional abbreviations follow Leviton et al. (1985), except for Lake Biwa Museum, Shiga Prefecture, Japan (LBM), and the private collection of M. Hori (Zm). Ingroup taxa.—Cyprichromini: Cyprichromis leptosoma, LBM 25148*, 26086*, 51-71 mm SL; C. microlepidotus, HUMZ 127578, 127976, 137463, 137465, 137742*, 90-97mm SL; C. pavo, Zm 02543-1, 02543-2, 93-101 mm SL; C. zonatus, LBM 25165*, 25178*, 72-77mm SL; Cyprichromis sp., HUMZ 125341*, 157401*, LBM 25169*, 80-88mm SL; Paracyprichromis brieni, HUMZ 118395*, 122560*, 157399*, LBM 26095, 26178, 68-90mm SL; P. nigripinnis, four specimens of Zm 530 (two of them dissected*), 50­ 59 mm SL. 5 mm 5 mm Outgroup taxa.—Bathybatini: Bathybates fasciatus, HUMZ 138010*, 145mm SL; Trematocara marginatum, Fig. L Lateral view of infraorbitals of Cyprichromis microlepidotus HUMZ 128729*, 46 mm SL. Benthochromini: (A), Paracyprichromis nigripinnis (B), and P. brieni (C, D). A, D From Benthochromis tricoti, HUMZ 128982*, 111mm SL. Takahashi (2003b) Boulengerochromini: Boulengerochromis microlepis, HUMZ 123097*, 160 mm SL. Cyphotilapiini: , HUMZ 137775*, 121mm SL. Ectodini: Ectodus (type B in Ectodus, C in Trematocara, D in Lamprologus, F descampsi, HUMZ 116672*, 70 mm SL. Eretmodini: in Bathybates, and G in Gnathochromis); (1) type H: in Eretmodus cyanostictus, HUMZ 125254*, 67mm SL. Paracyprichromis. Greenwoodochromini: Greenwoodochromis christyi, Infraorbitals of Cyprichromini number six or seven (five, HUMZ 128465*, 78 mm SL. Haplochromini: Astatotilapia resulting from the fusion of two bones, in one specimen each burtoni, HUMZ 125825*, 61mm SL. Lamprologini: of Cyprichromis zonatus and Cyprichromis sp.), continu­ Lamprologus lemairii, HUMZ 128372*, 166mm SL. ously arranged from the anteriormost infraorbital (IO1) to Limnochromini: Gnathochromis permaxillaris, HUMZ the dermosphenotic in a single row (Fig. 1). Large, triangu­ 123245*, 124mm SL. Perissodini: Perissodus microlepis, lar platelike IO1 with a convex ventral margin. The other HUMZ 125121*, 91mm SL. Tilapiini: Oreochromis niloticus infraorbitals (i.e., IO2 to dermosphenotic) comprise a series eduardianus, HUMZ 116860*, 131mm SL. Tropheini: of narrow, usually elongated bones. A lateral line on IO1 Tropheus moorii, HUMZ 122563*, 99 mm SL. Tylochromini: of Cyprichromis branched into five tubules, opening at Tylochromis polylepis, HUMZ 125794*, 95mm SL. New these external ends (Fig. 1A), whereas four tubules in tribe (sensu Takahashi, 2003a): "Ctenochromis” benthicola, Paracyprichromis (Fig. 1B-D) (five in one specimen of P. HUMZ 127370*, 80mm SL. nigripinnis). The series of narrow infraorbitals (i.e., IO2 to dermosphenotic) of Cyprichromis bears a tubelike struc­ ture, which extends from the anterior end to the posterior Results end of the bone series (Fig. 1A), whereas no tubelike struc­ ture on anterior part of the series in Paracyprichromis (Fig. Characters for analysis. Characters and state numbers 1B-D). In P. nigripinnis, the dorsolateral surface of this part correspond to the numbers in the data matrix (Table 1). projects laterally, forming a ridge continuing from anterior Among all the observed internal and external morphologi­ end of IO2 to posterior end of IO4 or to anterior third of cal features, six informative characters for the cladistic IO5 (Fig. 1B); IO5 to dermosphenotic are tubelike bones. In analysis were found. P. brieni, the ridge is present on the dorsolateral surface Character 1: infraorbitals.—(0) generally type A (sensu between the middle of IO2 and the posterior end of IO3 Takahashi, 2003b), but various types occur in outgroup taxa (Fig. 1C), or absent (Fig. 1D), these states are not separable Phylogenetic analysis of Cyprichromini 3

Table 2. Ranges of number of scale rows between upper lateral line and body axis, abdominal and caudal vertebral counts, difference between these counts (abdominal vertebrae minus caudal vertebrae), and procurrent rays in Cyprichromini

Scale rows between upper Vertebrae Procurrent rays lateral line and body axis Abdominal Caudal Difference Upper Lower

Cyprichromis leptosomaa 3 18-20 16-17 1-4 11 10 Cyprichromis microlepidotusa 4-5 19-20 15-17 2-4 11-12 10-11 Cyprichromis pavoa 4 20-21 17-18 2-4 11-12 11-12 Cyprichromis zonatusb 3-4 20-21 16-18 2-5 10-11 11 Cyprichromis sp.a 3-4 20-21 16-18 2-5 11-12 10-12 Paracyprichromis brieni 2 17 17-18 -1 -0 9 8-9 Paracyprichromis nigripinnis 2 17 18 -1 8 7-8 aVertebral data from specimens of present study and Takahashi et al. (2002) bNumber of scale rows and vertebral counts from specimens of present study and Takahashi et al. (2002)

because of the intraspecific variation; an incomplete tube­ Outgroup like structure is sometimes present on IO3 that is open Paracyprichromis brieni posteriorly but closed anteriorly (Fig. 1D); IO4 to Paracyprichromis nigripinnis dermosphenotic are tubelike bones. Takahashi (2003b) classified the infraorbitals of Tan­ Cyprichromis pavo ganyikan cichlids into eight types and treated Cyprichromis Cyprichromis zona tus as a variation of type A, the most plesiomorphic arrange­ Cyprichromis leptosoma ment among African cichlids. The present observations Cyprichromis microlepidotus agree with his allocation of Cyprichromis. Regarding Paracyprichromis, he did not observe P nigripinnis, but P Cyprichromis sp. brieni. He included the infraorbitals of P. brieni in type H, Fig. 2. The most parsimonious tree of six morphological characters for which differed from other types in the absence of a tubelike Cyprichromini (tree length 9, consistency and retention indices 1.000). structure on IO2, and the presence of an incomplete tube­ Character numbers, with plesiomorphic (left) and apomorphic (right) like structure that is closed anteriorly on IO3 and its con­ state numbers in parentheses, correspond to those listed in Table 1. tinuous arrangement from IO1 to the dermosphenotic. In Characters 2, 4, and 6 not indicated, owing to uncertain optimization the present study, structures of IO3 varied among specimens of P. brieni, type H being partly redefined: IO2 lacks the tubelike structure (vs. bears tubelike structure in types A, E, F, and G), IO3 lacks a tubelike structure or has an incom­ Character 4: scale rows between upper lateral line and plete tubelike structure that is closed anteriorly (vs. pos­ body axis.—(0) two: in Paracyprichromis; (1) three to five: in sesses a tubelike structure that is open at both ends in types Cyprichromis. The character is coded such that the states A, B, E, F, and G), and infraorbitals are continuously ar­ do not overlap in any ingroup taxa (see Table 2). In the ranged from IO1 to the dermosphenotic (vs. discontinu­ outgroup taxa, the scale rows varied from one to five, the ously arranged in type D, lacks the dermosphenotic in type character being coded as polymorphic (0&1) in the compos­ C). Among Tanganyikan cichlids, this condition is exclu­ ite outgroup. sively found in P. brieni and P. nigripinnis. Character 5: caudal fin.—(0) generally monochromatism; Character 2: abdominal vertebrae.—(0) equal in number (1) dichromatism, i.e., presence of the obviously distinct two to or fewer than caudal vertebrae (Table 2): in Paracy­ color patterns (for example, blue- and yellow-tails) between prichromis; (1) greater number than caudal vertebrae: in males of the same population (Konings, 1998: photographs Cyprichromis. In outgroup taxa, abdominal vertebral num­ on p. 149): in Cyprichromis leptosoma, C. microlepidotus, bers were generally equal to or fewer than caudal vertebrae, and Cyprichromis sp. but greater in Benthochromis (abdominal: 18, caudal: 17), Character 6: number o f procurrent rays.—(0) 7-9 on each Oreochromis (16, 13), and Cyphotilapia (16 and 15). Fur­ upper and lower lobe: in Paracyprichromis; (1) 10-12: in thermore, the vertebral numbers of Benthochromis are in­ Cyprichromis. The character is coded such that the states cluded within the ranges for Cyprichromis. The character do not overlap in any ingroup taxa (see Table 2). In the was therefore coded as polymorphic (0&1) in the composite outgroup taxa, procurrent ray numbers varied from 5 to 13, outgroup. the character being coded as polymorphic (0&1) in the Character 3: posterior extension o f the abdominal cavity composite outgroup. and swim bladder.—(0) generally not extending beyond Cladistic analysis. A matrix of six characters for the seven anal fin origin (Poll, 1981: pl. 3B); (1) extending beyond anal ingroup taxa, plus one composite outgroup, is shown in fin origin (Poll, 1981: pl. 3A): in Cyprichromis. Table 1. As a result of the analysis, one maximum-parsimony 4 T. Takahashi tree was obtained (Fig. 2). The trichotomy within clades a loan of specimens and references from the HUMZ photo library; to M. and b are the result of insufficient rather than conflicting Hori (Department of Zoology, Graduate School of Science, Kyoto data, no characters being found to resolve the relationships University) for the loan of specimens and the information about col­ of these taxa. oration; to J. Snoeks and G.G. Teugels (MRAC) for the loan of speci­ mens; and to G.S. Hardy (Ngunguru, New Zealand) and M. Tomokuni (NSMT) for advice and comments on the manuscript. I am also particu­ Discussion larly thankful to M.J.B. Gashagaza (Environmental Research Develop­ ment, Rwanda), M. Nshombo, M.R. Mbuya, and other staff of the Center for Hydrological Research in Uvira, D.R. Congo, and L.M. Poll (1986) recognized two genera, Paracyprichromis and Mwape, H. Phiri, and other staff of the Lake Tanganyika Research Unit Cyprichromis, in the tribe Cyprichromini, defining the in Mpulungu, Zambia, for assisting during the survey. This study was former as having a nonelongated swim bladder (vs. elon­ partly supported by a Domestic Research Fellowship from Japan Sci­ gated, extending posteriorly beyond anal fin origin in ence and Technology Corporation, Grant-in-Aid for JSPS Fellows, Cyprichromis), fewer abdominal vertebrae than caudal ver­ and Grants-in-Aid for Overseas Scientific Survey (Nos. 04041078 and tebrae (vs. more than caudal vertebrae), fewer anal-fin soft 04044088) from the Ministry of Education, Culture, Sports, Science and rays (7-10 vs. 11-13), more spines and fewer soft rays in the Technology, Government of Japan. dorsal fin (XIV-XVIII, 11-14 vs. XII-XV, 14-18), and fewer scales on the longitudinal line (34-39 vs. 39-71) and around the caudal peduncle (14-16 vs. 16-17). The non-elongated Literature Cited swim bladder is, in fact, plesiomorphic, being the general condition in Tanganyikan cichlids (Poll, 1981). In addi­ Buscher HH (1994) Cyprichromis pavo n. sp.: ein neuer Cichlide aus tion, the numbers of fin rays [10-13 anal-fin soft rays dem Tanganjikasee (Cichlidae, Cyprichromini). DATZ 46:257-263 Konings A (1998) Tanganyika cichlids in their natural habitat. Cichlid in Cyprichromis (Takahashi et al., 2002)] and scales both Press, Miami overlap between the genera. Furthermore, the numbers Leviton AE, Gibbs RH Jr, Heal E, Dawson CE (1985) Standards in of abdominal and caudal vertebrae, fin rays, and scales of herpetology and ichthyology: Part I. Standard symbolic codes for Paracyprichromis are all included within the ranges of institutional resource collections in herpetology and ichthyology. other Tanganyikan cichlids (present specimens; Poll, 1956). Copeia 1985:802-832 Thus, the characters proposed by Poll (1986) were not Poll M (1956) Poissons Cichlidae. Resultats scientifiques. Exploration synapomorphies for Paracyprichromis species. hydrobiologique du Lac Tanganika (1946-1947). Inst R Sci Nat Belg Takahashi (2003b) indicated that among Tanganyikan 3(5B):1-619 cichlids, Paracyprichromis brieni exclusively had type H Poll M (1981) Contribution a la faune ichthyologique du lac Tanganika. infraorbitals. Specimens of P. nigripinnis, however, had Revision du genre Limnochromis Regan, 1920. Et d’une espece not been examined at that time (he wrote “P. nigrifrons” nouvelle: Cyprichromis brieni. Ann Soc R Zool Belg 111:163-177 by mistake; Takahashi, 2003b: p. 22, l. 4). The present Poll M (1986) Classification des Cichlidae du lac Tanganika. Tribus, cladogram, including both Paracyprichromis species, indi­ genres et especes. Acad R Belg Mem Cl Sci 45:1-163 cates the genus to be monophyletic, supported by type H Scheuermann H (1977) A partial revision of the genus Limnochromis infraorbitals (state 1 of character 1; Figs. 1B-D, 2). Regan 1920. Cichlidae (British Cichlid Association) 3:69-73 Regarding Cyprichromis, only the elongated swim blad­ Sturmbauer C, Meyer A (1993) Mitochondrial phylogeny of the der is valid as a synapomorphy supporting the genus (Fig. 2; endemic mouthbrooding lineages of cichlid from Lake state 1 of character 3). Other diagnostic characters pro­ Tanganyika in Eastern Africa. Mol Biol Evol 10:751-768 Takahashi T (2002) Systematics of the tribe Trematocarini (Perci- posed by Poll (1986) (more abdominal vertebrae than cau­ formes: Cichlidae) from Lake Tanganyika, Africa. Ichthyol Res dal vertebrae, 11-13 anal fin soft rays, 12-15 spines and 49:253-259 14-18 soft rays in the dorsal fin, 39-71 scales on the longitu­ Takahashi T (2003a) Systematics of Tanganyikan cichlid fishes dinal line, and 16-17 scales around the caudal peduncle) did (Teleostei: Perciformes). Ichthyol Res 50:367-382 not constitute synapomorphies, because they were all in­ Takahashi T (2003b) Comparative osteology of the infraorbitals in cluded in the ranges of other Tanganyikan cichlids (present cichlid fishes (Teleostei: Perciformes) from Lake Tanganyika. Species data; Poll, 1956). Divers 8:1-26 Takahashi T, Hori M, Nakaya K (2002) New species of Cyprichromis Acknowledgments I express my sincere thanks to K. Nakaya (Perciformes: Cichlidae) from Lake Tanganyika, Africa. Copeia (HUMZ) and H. Imamura (The Hokkaido University Museum) for the 2002:1029-1036