An Annotated Checklist of the Macrodasyidan Gastrotricha from India

Zootaxa 4545 (4): 495–510 ISSN 1175-5326 (print edition) https://www.mapress.com/j/zt/ Article ZOOTAXA Copyright © 2019 Magnolia Press ISSN 1175-5334 (online edition) https://doi.org/10.11646/zootaxa.4545.4.3 http://zoobank.org/urn:lsid:zoobank.org:pub:B0910D8D-E387-4BDB-941F-40D06CBBBAD0 An annotated checklist of the macrodasyidan Gastrotricha from India

TAPAS CHATTERJEE1, GEETHA PRIYALAKSHMI2 & M. ANTONIO TODARO3 1Crescent International School, Bario, Govindpur, Dhanbad 828109, Jharkhand, India. E-mail: [email protected] 2Department of Zoology, Bharata Mata College, Thrikkakara, Kerala, India. E-mail: [email protected] 3Dipartimento di Scienze della Vita, Università di Modena e Reggio Emilia, via G. Campi 213/D, I-41125 Modena, Italy. E-mail: [email protected]

Abstract

We present a checklist of the macrodasyidan Gastrotricha fauna of India derived from original articles and comprehensive monographies regarding the Indian Fauna. Taxa and specimens described from India are discussed with special attention to their status, especially those species previously known from distant geographic areas. A total of 43 species have been recorded from 4 States and 2 Union territories. A careful taxonomic assessment indicated that many species are in need of re-description as the reported anatomical traits are not sufficient to grant a modern, robust identification. The situation is particularly poor for two species (Macrodasys indicus Govindankutty & Nair, 1969 and Paradasys lineatus Rao, 1980), which consequently, are considered here to be species inquirendae; moreover, the Indian records of Tetranchyroderma hystrix and T. massiliense reported from Kerala are doubtful and consequently the two species should not be included among the fauna of the Indian region until proper evidence is found. It is necessary to unravel the true identities of many Indian species through a comparison to topotypical material. We recommend that future comparisons between related species and conspecifics from different populations to include molecular sequence data

Key words: Gastrotricha, Macrodasyida, checklist, India, distribution

Introduction

Gastrotricha constitute one of the most interesting and taxonomically challenging groups of meiobenthic marine and freshwater invertebrates. Gastrotrichs are microscopic, free-living bilaterally symmetrical, acoelomate worms with a cosmopolitan distribution. There are about 840 species grouped into two orders: Macrodasyida, comprising around 365 strap-shaped species, all but two marine or estuarine, and Chaetonotida with 475 mostly tenpin shaped species, three-fourth of which is freshwater forms (e.g., WoRMS 2018). Approximately, 80 species have been recorded from India, of which about half are exclusively marine and belong to the order Macrodasyida. We provide here a list of these species that have both National and global distributions, and with taxonomic remarks in light of the current practices applied to Gastrotricha. Several of the macrodasyidan species present in India were originally described from European coasts and therefore may have cosmopolitan distributions (sensu Sterrer 1973). A close inspection of these descriptions could provide support or disprove their current systematization, thereby affecting our understanding of their national and global biogeography.

Methods

The present checklist of the macrodasyidan Gastrotricha fauna of India derives from original articles and monographies regarding the Indian fauna. The genera and species within each family or subfamily are arranged in an alphabetical sequence. For each species, the references are arranged State-wise alphabetically, and within each State chronologically. Some localities names were changed, thus to avoid confusion in the checklist the new name of the locality is reported and the formerly known name is kept in brackets, e.g., Odisha (Orissa). Habitat is defined

Accepted by W. Sterrer: 19 Nov. 2018; published: 21 Jan. 2019 495 according to the Indian sample sites and is only generalized for each species. Taxa and specimens described from India are discussed with special attention to their status, especially those species previously known from distant geographic areas. Additional information e.g. taxonomic keys and/or synonymies, are provided if necessary and available.

Results

Phylum GASTROTRICHA Metschnikoff, 1865

Order Macrodasyida Remane, 1925 [Rao & Clausen, 1970]

Family Cephalodasyidae Hummon & Todaro, 2010

Genus Cephalodasys Remane, 1926

Cephalodasys caudatus Rao, 1981

Records from India. ODISHA (Orissa): Puri—Rao (1981a, 1989); GENERAL RECORD: Naidu & Rao (2004). Habitat. Marine intertidal zone inhabiting coarse and medium sand, 5–10 cm below surface between low and half tide levels. Distribution. India (Bay of Bengal). Remarks. A recent key to species of the genus Cephalodasys is available from Kieneke et al. (2015).

Cephalodasys turbanelloides (Boaden, 1960)

= Paradasys turbanelloides Boaden, 1960 (syn. by Hummon, 1974)

Records from India. ANDHRA PRADESH: Visakhapatnam (Waltair), Bimlipatnam—Ganapati & Rao (1967), Rao & Ganapati (1968b), Sarma & Chandramohan (1981); KERALA: Fort Kochi, Neendakara, Karunagapally— Govindankutty & Nair (1967); GENERAL RECORD: Naidu & Rao (2004). Habitats (as in Indian records). Marine, Intertidal; coarse medium sand, 10–15 cm below surface, between low and mid-water levels. Distribution. North Sea, Mediterranean Sea, Gulf of Mexico, India. Remarks. Descriptions of the specimens from India are incomplete as they lack references to the frontal organ and to male pore in the studied specimens. This lack data weakens the specific identification of the Indian specimens.

Genus Mesodasys Remane, 1951

Mesodasys hexapodus Rao & Ganapati, 1968

Records from India. ANDHRA PRADESH: Visakhapatnam (Waltair)—Rao & Ganapati (1968a); GENERAL RECORD: Naidu & Rao (2004). Habitat. Marine; coarse sand at a depth of 20–30 cm between low and mid-water levels. Distribution. So far the species appears to be endemic to India. Remarks. Naidu & Rao (2004) indicated the species to be present also in North America (Florida); however, we could not find any original reference in this regard. Very likely the record of Macrodasys hexadactylis in Florida (see Hummon 2010) may have generated the confusion. Consequently M. hexapodus should be considered endemic to India.

Paradasys lineatus Rao, 1980

Records from India. ANDHRA PRADESH: Visakhapatnam (Waltair), Krishnapatnam beach—Rao (1980a); ODISHA: Gopalpur—Rao (1989); GENERAL RECORD: Naidu & Rao (2004). Habitat. Marine, intertidal; Medium sand, 10 cm below surface. Remarks. The structure of the spermatozoa, described as a filiform cell with a corkscrew head, cast doubt on the affiliation of the Indian specimens to the genus Paradasys (Ruppert & Shaw 1977; Guidi et al. 2017). The shape, size (up to 800 µm in total length), organization of the reproductive system, and structure of the spermatozoa would suggest their affiliation to the genus Cephalodasys instead. Future research could provide support to our working hypothesis. In the meantime we consider the taxon to be species inquirenda (i.e., a species of doubtful identity needing further investigation).

Paradasys littoralis Rao & Ganapati, 1968

Records from India. ANDHRA PRADESH: Visakhapatnam (Waltair), Scandal point—Rao & Ganapati (1968a); ODISHA: Puri—Rao (1989); KERALA: Fort Kochi, Neendakara, Karunagapally—Govindankutty & Nair (1967); WEST BENGAL: Medinipur, South 24 Parganas—Sanyal et al. (2012); GENERAL RECORD: Naidu & Rao (2004). Habitat. Marine, intertidal; coarse & medium sand, 10–20 cm below surface, between low and mid tide levels. Distribution. Known only form India. Remarks. Additional information on this species is desirable as the current description of the male apparatus (e.g., Fig. 13 Naidu & Rao 2004) departs from other species of the genus (e.g., Remane 1934).

Genus Pleurodasys Remane, 1927

Pleurodasys helgolandicus Remane, 1927

= Pleurodasys megasoma Boaden, 1963

Records from India. KERALA: Fort Kochi (Cochin), Karunagapally—Govindankutty & Nair (1969, 1972) as Pleurodasys megasoma; GENERAL RECORD: Naidu & Rao (2004). Habitat (as in Indian records). Marine, intertidal, subtidal; fine and medium grained sediment, less frequently in intertidal zone, more widespread in submersed sand. Distribution. North Sea; Mediterranean Sea; India (Arabian Sea). Remarks. The Indian specimens are reported to bear a pair extraordinary organs ("lateral feet" of Naidu and Rao), each comprised of three adhesive tubes, while in the European specimens, these organs are composed of four tubes (Marotta et al., 2008). This difference, and the geographic distance from the type locality, call for a better morphological comparison between Indian and European populations. Ideally, such comparisons should also include genetic data as well as specimens from conspecifics, e.g., P. incomptus Todaro, Dal Zotto, Bownes & Perissinotto, 2017 described from South Africa (see Todaro et al. 2017). We note positively that for some of the Indian populations information on seasonal dynamics are available (Govindankutty & Nair 1972). This type of information is much needed but rarely available for gastrotrich species.

Family Dactylopodolidae Strand, 1929

GenusDactylopodola Strand, 1929

Dactylopodola indica (Rao & Ganapati, 1968)

= Dactylopodalia indica Rao & Ganapati, 1968

CHECKLIST OF MACRODASYIDAN GASTROTRICHA FROM INDIA Zootaxa 4545 (4) © 2019 Magnolia Press · 497 Records from India. ANDAMAN & NICOBAR ISLANDS—Rao (1975, 1980b); ANDHRA PRADESH: Palm beach, Visakhapatnam (Waltair)—Rao & Ganapati (1968a); LAKSHADWEEP: Agatti, Bangaram—Rao (1991); ODISHA: Puri, Konark—Rao & Ganapati (1968a); Rao (1989); WEST BENGAL: Medinipur—Sanyal et al. (2012); GENERAL RECORD: Naidu & Rao (2004). Habitat. Marine, littoral; medium sand, 10–30 cm below surface near mid-water level. Distribution. This species has been reported only from India (Bay of Bengal and Arabian Sea). Remarks. Nomenclature and functional role of the accessory reproductive organs as indicated for the Indian specimens should be revised in light of the recent literature (e.g., Kieneke & Schmidt-Rhaesa 2015).

Family Macrodasyidae Remane, 1926

Genus Macrodasys Remane, 1924

Macrodasys andamanensis Rao, 1993

Record from India. ANDAMAN & NICOBAR ISLANDS: Little Andaman: Bomila creek, Butler Bay—Rao (1993); GENERAL RECORD: Naidu & Rao (2004). Habitat. Marine; coarse and medium sand with little detritus, 5–10 cm below surface, between low and half tide levels in intertidal zone. Distribution. Indian Ocean: Bay of Bengal. Remarks. In general, the description of the species appears robust; however, the tail is reported to be pseudo- segmented, a condition that is doubtful.

Macrodasys caudatus Remane, 1927

Records from India. ANDHRA PRADESH: Visakhapatnam (Waltair), Bimlipatnam—Ganapati & Rao (1967), Sarma & Mohan (1981); ODISHA (Orissa): Konarak—Rao (1969); KERALA: Azkikode, Fort Kochi (Cochin), Karunagapally, Neendakara, Ashtamudi—Govindankutty & Nair (1969), Nair & Govindankutty (1972), Aziz & Nair (1983), Nair et al. (1984); GENERAL RECORD: Rao (1972), Naidu & Rao (2004), Rao (2005). Habitat. Marine, intertidal; coarse sand, 15–20 cm below surface, between low and mid-water levels. Distribution. Widespread, recorded from numerous areas and localities outside the type locality (off palazzo Donn’Anna, Naples, Italy) including the West and East Mediterranean Sea, Northern Europe, British Isles, USA (Atlantic, Gulf coasts and Florida Keys) and Somalia (as M. cf caudatus). Remarks. According to the literature, the species appears to be eurytopic, having been found in fine to coarse sand, mostly with detritus or mud, but also in Amphioxus sand and among algae (e.g., Todaro et al. 1992).The wide distribution and the variety of habitats call for a better comparison of the geographic populations; future comparisons should include molecular data. According to W.D. Hummon (personal communication to MAT), the records of M. caudatus from the USA actually should be considered records of M. meristocytalis Evans, 1994; similarly, the Indian record from Kerala beaches is most unlikely to be M. caudatus, due to the lack of information regarding the shape and size of the accessory sexual organs (i.e., caudal- and frontal organ). It is evident that new material is needed to perform a robust identification of these animals.

Macrodasys hexadactylis Rao, 1970

Records from India. ANDHRA PRADESH: Pudimadaka, Visakhapatnam (Waltair)—Rao (1970); GENERAL RECORD: Naidu & Rao (2004). Habitat (as in Indian records). Marine, intertidal; medium sand, 30–40 cm below surface, between low and half tide level. Distribution. India (Bay of Bengal); Japan (Kasado island as M. cf hexadactylis); USA (Florida, Hummon 2010). Remarks. Nomenclature and functional role of the accessory reproductive organs as indicated in the original description should be revised in light of the recent literature (e.g., Kieneke & Schmidt-Rhaesa 2015).

Records from India. KERALA: Azhikode, Fort Kochi (Cochin)—Govindankutty & Nair (1969, 1972), Nair & Govindankutty (1972); GENERAL RECORD: Naidu & Rao (2004). Habitat. Intertidal, marine; medium sand near mid-tide level. Remarks. Hummon & Todaro (2010) commented—“The proper name is M. indicus, as in the text, and not M. idicus, as occurs in Fig. 7; this is as determined by the first reviser, Hummon, 2008b:127 (ICZN 24.2.2)”. We agree with Hummon & Todaro (2010) to consider this taxon to be species inquirenda as the available morphological information is insufficient for a reliable identification of the Indian specimens. Indeed as it is sketched the specimens look more like a Mesodasys than a Macrodasys.

Macrodasys lakshadweepensis Hummon, 2008

= Macrodasys lakshadweepense Hummon, 2008 = Macrodasys indica Rao, 1991.

Records from India. LAKSHASWEEP: Minicoy (Rao, 1991); GENERAL RECORD: Naidu & Rao (2004). Habitat. Marine intertidal; coarse and medium coralline sands, 5 cm below surface between low and high tide levels. Distribution. India (Arabian Sea). Remarks. Hummon (2008) named this species as Macrodasys lakshadweepense because the original name Macrodasys indica Rao, 1991 did not comply with the nomenclature rules. However, once corrected to M. indicus, it became a junior primary homonym of M. indicus Govindankutty & Nair, 1969. Finally, Hummon & Todaro (2010) corrected the species name from M. lakshadweepense to M. lakshadweepensis according to the genus gender.

Macrodasys waltairensis Rao & Ganapati, 1968

Records from India. ANDHRA PRADESH: Visakhapatnam (Waltair)—Rao & Ganapati (1968a); ODISHA (Orissa): Gopalpur—Rao (1969); WEST BENGAL: Medinipur,—Sanyal et al. (2012); GENERAL RECORD: Naidu & Rao (2004). Habitat. Marine; coarse sand with shell gravel, at a depth 30 cm near low water level. Distribution. Species so far known only from India (Bay of Bengal). Remarks. The proper name is Macrodasys waltairensis, and not M. waltaironsis, as occurs in Fig. 7 of the original description (see Rao & Ganapati 1968a).

Genus Urodasys Remane, 1926.

Urodasys viviparus Wilke, 1954

Records from India. ANDHRA PRADESH: Visakhapatnam (Waltair)—Ganapati & Rao (1967), Rao & Ganapati (1968a); ODISHA (Orissa): Puri—Rao (1989); ANDAMAN & NICOBAR ISLANDS: Mayabandar—Rao (1975, 1980b); LAKSHASDWEEP: Agatti, Bangaram—Rao (1991); WEST BENGAL: Medinipur—Sanyal (2012); GENERAL RECORD—Rao (1972), Naidu & Rao (2004), Rao (2005). Habitat (as in Indian records). Coarse sand with fine shell gravel and a little detritus in the intertidal zone near half tide level. Distribution. Widespread species, recorded from numerous areas and localities outside the type locality (off Castel dell’Ovo, Naples, Italy); these include West and East Mediterranean Sea, North Europe, British Islands, Bermuda, USA (Atlantic and Gulf coasts of Florida), Caribbean Sea, Brazil, Red Sea, Maldives, Somalia (as U. cf viviparus) and India. Remarks. The species has been found at different depths (from littoral to 33 m) and in sediments of various grain size in general rich in organic detritus. A recent phylogenetic analysis of the genus Urodasys based on a

CHECKLIST OF MACRODASYIDAN GASTROTRICHA FROM INDIA Zootaxa 4545 (4) © 2019 Magnolia Press · 499 molecular genetic data found specimens of U. viviparus from geographic distant populations (e.g., Cayman islands and Brazil) clustering together, testifying to their common origin (Atherton & Hochberg 2015).

Family Planodasyidae Rao & Clausen, 1970

Genus Crasiella Clausen, 1968

Crasiella indica Rao, 1981

Records from India.ODISHA (Orissa): Gopalpur—Rao (1981b); WEST BENGAL: South 24 Parganas—Sanyal et al. (2012); GENERAL RECORD: Naidu & Rao (2004). Habitat. Marine, Intertidal, subtidal; clean medium sand, 5 cm below surface. Distribution. India (Bay of Bengal). Remarks. In the description, the term “pharyngeal knobs” has been used to denote the pharyngeal pores. This may cause confusion as the term pharyngeal knobs has also been used for the drumstick-like sensorial organs present in Pleurodasys helgolandicus. Furthermore, nomenclature and functional role of the accessory reproductive organs as indicated in the original description should be revised in light of the recent literature (e.g., Kieneke & Schmidt-Rhaesa 2015).

Genus Planodasys Rao in Rao & Clausen, 1970

Planodasys littoralis Rao, 1993

Records from India.ANDAMAN & NICOBAR ISLANDS: Harminder Bay—Rao (1993); GENERAL RECORD: Naidu & Rao (2004). Habitat. Marine, intertidal, subtidal; medium sand with little detritus, 10 cm below surface, between low and mid water level. Distribution. India (Bay of Bengal). Remarks. Currently, the genus Planodasys includes two species both of which are from India (see also below). Description of both species are based on bright-field microscopy only; it is possible that advanced optical techniques (e.g., DIC) may reveal internal structures so far undetected (e.g., the frontal organ) and/or may provide a better insight on the structure of the very long cylindrical caudal organ (bursa copulatrix in the original description). As the layout of the reproductive system has been demonstrated to be of phylogenetic significance (e.g., Todaro et al. 2011), reliable information in this regard is relevant beyond taxonomy. Likewise, the inclusion of Planodasys species in the ongoing phylogenetic studies based on molecular markers (e.g., Todaro et al. 2012, 2014, 2015) could confirm or disprove the current in-group systematization of the family Planodasyidae (Guidi et al. 2014). In our opinion, and as a possible working hypothesis, Planodasys should be considered a junior synonym of Crasiella as it lacks reliable autapomorphic traits that could make it a distinct taxon. However, until additional information will be gathered, we continue to consider Planodasys to be a separate genus.

Planodasys marginalis Rao & Clausen, 1970

Records from India. ANDHRA PRADESH: Palm beach, Visakhapatnam (Waltair)—Rao & Clausen (1970); GENERAL RECORD: Naidu & Rao (2004). Habitat. Marine, Intertidal, subtidal; medium sand with fine shell gravel and little detritus, between low and half-tide levels Distribution: India (Bay of Bengal). Remarks. See comment above in the Remarks section of Planodasys littoralis.

Subfamily Diplodasyinae Ruppert, 1978

Genus Acanthodasys Remane, 1927

Acanthodasys aculeatus Remane, 1927

Records from India. ANDHRA PRADESH: Visakhapatnam (Waltair)—Ganapati & Rao (1967), Rao & Ganapati (1968b); ODISHA (Orissa): Bahuda estuary—Rao (1989); ANDAMAN & NICOBAR ISLANDS: West Bay, Mayabandar, north Andaman; Car Nicobar, East point—Rao (1975, 1980b, 1993). LAKSHADWEEP: Kavaratti— Rao (1991); WEST BENGAL: Medinipur,—Sanyal et al. (2012); GENERAL RECORD—Rao (1972), Naidu & Rao (2004), Rao (2005). Habitat (as in Indian records). Marine, Intertidal; Medium and coarse coralline sand with little detritus, 20 cm below surface between half and low tide level Distribution. Widespread species, recorded from numerous areas and localities outside the type locality (Düne-Helgoland, Germany), these include North Europe, British islands, Mediterranean Sea, Black Sea, Atlantic and Gulf coasts of the USA, Red Sea, Maldives, and India (Arabic sea and Bay of Bengal). Remarks. According to the literature, the species appears to be eurytopic, having been found at different depths and in sediments of various grain sizes. The wide distribution, the variety of habitats, and description, which sometime are discordant, call for a better comparison of the geographic populations, hopefully based also on molecular data.

Genus Diplodasys Remane, 1927

Diplodasys remanei Rao & Ganapati, 1968

Records from India. ANDHRA PRADESH: Scandal point, Visakhapatnam (Waltair)—Rao & Ganapati (1968a); GENERAL RECORD: Naidu & Rao (2004). Habitat. Marine, intertidal; coarse and medium sand, 20–40 cm below surface between mid and low tide level. Distribution. So far known only from India (Bay of Bengal) Remarks. The body shape, which is elongate and rather narrow, appears unique among Diplodasys species, approaching that of some Acanthodasys species i.e., A. caribbeanensis Hochberg & Atherton, 2010 and A. comtus Lee, 2012. The latter species also have the dorsal side covered by large plates, although those of the medial column are provided with spines, a trait not present in D. remanei. Future studies will confirm or disprove the current affiliation of the Indian specimens (and similar species) to the genus Diplodasys.

Subfamily Thaumastodermatinae Ruppert, 1978

Genus Pseudostomella Swedmark, 1956

Pseudostomella andamanica Rao, 1993

Records from India. ANDAMAN & NICOBAR ISLANDS: Dudong creek—Rao (1993); GENERAL RECORD: Naidu & Rao (2004). Habitat. Marine, intertidal; medium sand rich in organic detritus, 10 cm below surface, near mid water level. Distribution. India (Bay of Bengal). Remarks. It has been recorded so far only from the Bay of Bengal, India.

Records from India. KERALA: Cherai beach—Priyalakshmi et al. (2007). Habitat. Marine, intertidal; moderately well sorted, clean medium sand, 15–17 cm below surface near mid- water level. Distribution. India (Arabian Sea). Remarks. It has been recorded so far only from India.

Pseudostomella indica Rao, 1970

Records from India. ANDHRA PRADESH: Palm beach, Visakhapatnam (Waltair)—Rao (1970); ODISHA: Gopalpur—Rao (1989); LAKSHADWEEP: Agatti—Rao (1991); WEST BENGAL: South 24 Parganas—Sanyal et al. (2012); GENERAL RECORD: Naidu & Rao (2004). Habitat. Marine, intertidal; medium sand, 10 cm below surface near mid-water level. Distribution. India (Bay of Bengal, Arabian Sea). Remarks. Endemic to India.

Pseudostomella malayica Renaud-Mornant, 1967

Records from India. ANDAMAN & NICOBAR ISLANDS: Butler Bay, east point in Car Nicobar—Rao (1975, 1980b, 1993); GENERAL RECORD: Naidu & Rao (2004). Habitat. Marine, intertidal; medium sand, 10 cm below surface near mid-water level. Distribution. Malaysia and India Remarks. There seems to be a discrepancy between the Indian and the Malaysian specimens with regard the arrangement of the tubes on the caudal pedicles. The Indian specimens are reported to have the medial tubes of the distal end in a ventral position while in the Malaysian gastrotrichs they are dorsal. Since in other Thaumastodermatidae these tubes, if present, are in a dorsal position, the description of Indian specimens should be considered incorrect in this respect.

Pseudostomella roscovita Swedmark, 1956

Records from India. ANDHRA PRADESH: Visakhapatnam (Waltair)—Ganapati & Rao (1967), Rao & Ganapati (1968b); ODISHA (Orissa): Puri, Konarak—Rao (1969), Nagabhusanam (1972); KERALA: Fort Kochi (Cochin), Azhikode beach, Neendakara beach—Govindankutty & Nair (1967, 1972), Nair & Govindankutty (1972), Rajan & Nair (1979); GENERAL RECORD: Naidu & Rao (2004). Habitat (as in Indian records). Marine, intertidal; fine and medium sands, 15 cm below surface near mid- water level. Distribution. Originally described from the Roscoff area (France), the species has been subsequently recorded from several areas and localities including, North Europe, British Islands, Mediterranean Sea, Atlantic and Gulf coast of the USA and India. Remarks. According to the literature, the species appears to be eurytopic, having been found at different depths and in sediments of various grain size. The wide distribution, the variety of habitats, and descriptions, which sometime are discordant, call for a better comparison of the geographic populations, hopefully comparisons will include molecular data.

Genus: Tetranchyroderma Remane, 1926

Tetranchyroderma cirrophorum Lévi, 1950

Records from India. ANDHRA PRADESH: Visakhapatnam (Waltair)—Ganapati & Rao (1967), Rao & Ganapati (1968b); GENERAL RECORD: Naidu & Rao (2004). Habitat. Marine, intertidal; coarse and medium sand, 20–30 cm below surface.

502 · Zootaxa 4545 (4) © 2019 Magnolia Press CHATTERJEE ET AL. Distribution. Originally found near Roscoff, France (Ile da Batz and ile the Callot) the species subsequently has been reported from several areas and localities including North Europe, British islands, Mediterranean Sea and India. Remarks. Lévi (1950) described it as T. cirrophora. Todaro et al. (2001) changed the species name ending from T. cirrophora to T. cirrophorum. Naidu & Rao (2004) misspelled this species name as T. cirriphora in species name and in legend of the Figure 18.

Tetranchyroderma indicum Rao & Ganapati, 1968

Records from India. ANDHRA PRADESH: Visakhapatnam (Waltair)—Rao & Ganapati (1968a); WEST BENGAL: Medinipur, South 24 Parganas—Sanyal et al. (2012); GENERAL RECORD: Naidu & Rao (2004). Habitat. Marine, intertidal; medium sand, 15–30 cm below surface near half-tide level. Distribution. India (Bay of Bengal). Remarks. Rao & Ganapati (1968a) reported it as Tetranchyroderma indica; Hummon & Todaro (2010) changed the species name ending from T. indica to T. indicum according to the genus gender.

Tetranchyroderma hystrix Remane, 1926

Records from India. KERALA: Neendakara—Rajan & Nair (1979). Habitat. It has been recorded in well sorted sand with grain size ranging mostly from 295 to 592 µm Remarks. This species has been recorded by Rajan & Nair (1979) from Kerala in their ecological work, along with other gastrotrichs species and meiofauna. There is no drawing and other taxonomic data of this species provided by them or any other author from India. Consequently, we consider this species finding as a doubtful record that require more evidence to prove the presence of this species on the Indian coast.

Tetranchyroderma littorale Rao, 1981

Records from India. ODISHA (Orissa): Puri, Konatak, Bahuda estuary—Rao (1981a, 1989); WEST BENGAL: Medinipur, South 24 Parganas—Sanyal et al. (2012); GENERAL RECORD: Naidu & Rao (2004). Habitat. Marine, intertidal; medium sand, 10 cm below surface between half and low tide level. Distribution. India (Bay of Bengal). Remarks. Rao (1981a) reported the species as Tetranchyroderma littoralis; Hummon & Todaro (2010) changed the species name ending from T. littoralis to T. littorale according to the genus gender.

Tetranchyroderma massiliense Swedmark, 1956

Records from India. KERALA: Azhikode beach, Neendakara beach—Govindankutty& Nair (1969), Rajan & Nair (1979); GENERAL RECORD: Naidu & Rao (2004). Habitat. Marine; Coarse sand grains of high water neap level. Distribution: France (Mediterranean sea and Atlantic coast); India (? see below), south Korea (? see below) Remarks. Govindankutty & Nair (1969) found a single specimen and the affiliation to the taxon was tentative. Indeed, based on the description and the drawing they provided, it seems very unlikely that the Indian specimen belongs to T. massiliense, because it was smaller (167 µm vs 290–310 µm in total length), had a single pair of cirrata tubes (vs two pairs) and a single pair of adhesive tubes between the caudal feet (vs two pairs). Naidu & Rao (2004) provided a description somewhat different i.e., the presence of two pairs of cirrata tubes and two pairs of adhesive tubes between the caudal feet; while the body length was the same as reported by Govindankutty & Nair (1969). Thus, it is unclear whether the Authors were referring to the same specimen or not. Regardless, the very high number of tetrancres rows, 48–50, indicated that even this description does not fit the original description of T.

CHECKLIST OF MACRODASYIDAN GASTROTRICHA FROM INDIA Zootaxa 4545 (4) © 2019 Magnolia Press · 503 massiliense. Considering all the above, we consider this species finding as a doubtful record that require more evidence to prove the presence of this species on the Indian coast. Furthermore, Naidu & Rao (2004) reported the species to be present also in South Korea, however we could not find evidence in this regard, and the species is not included among the invertebrate fauna of Korea (see Lee 2012).

Tetranchyroderma megastomum (Remane, 1927)

=Echinodasys megastoma Remane, 1927

Records from India. ANDHRA PRADESH: Visakhapatnam (Waltair)—Ganapati & Rao (1967), Rao & Ganapati (1968b). ODISHA: Puri—Rao (1969); GENERAL RECORD: Rao (1972), Naidu & Rao (2004). Habitat (as in Indian records). Marine, intertidal; medium sand, 20 cm below surface at mid-water level. Distribution. Originally found in the bay of Naples (Italy), the species has subsequently been reported from several areas and localities including the Mediterranean Sea, North Europe, British islands, Atlantic coast of the USA and India. Naidu & Rao (2004) indicated the species to be present also in South Korea, however we could not find evidence in this regard, and the species is not included among the invertebrate fauna of Korea (see Lee 2012). Remarks. Todaro et al. (2001) changed the species name ending from T. megastoma to T. megastomum according to the genus gender. According to the literature, the species appears to be eurytopic, having been found at different depths and in sediments of various grain size. The wide distribution, the variety of habitats and descriptions, some of which are discordant, call for a better comparison of the geographic populations, hopefully based also on molecular data.

Tetranchyroderma paralittorale Rao, 1991

Records from India. LAKSHADWEEP: Androth—Rao (1991); GENERAL RECORD: Naidu & Rao (2004). Habitat. Marine, intertidal; coarse and clean coralline sand, 10 cm below surface, near half-tide level. Distribution. India (Arabian Sea). Remarks. Hummon & Todaro (2010) changed the species name ending from T. paralittoralis to T. paralittorale according to the genus gender.

Tetranchyroderma suecicum Boaden, 1960

Records from India. ODISHA: Konark—Rao (1969); KERALA: Fort Kochi (Cochin), Azhikode beach, Karunagapally—Govindankutty & Nair (1969), Nair & Govindankutty (1972); GENERAL RECORD: Naidu & Rao (2004). Habitat (as in Indian records). Marine, intertidal; medium to fine sand near mid-tide level. Distribution. Originally described from the western coast of Sweden (Gulmarsfjord), the species has been subsequently recorded form several areas and localities of North Europe, British islands and India. The presence of the species in North America (Alabama, Delaware and Virginia) reported by Naidu & Rao (2004) is not circumstantiated. Remarks. Luporini et al. (1973) changed the species name ending from T. suecica to T. suecicum according to the genus gender. The description of the Indian specimens is somewhat discordant with the original description and calls for a better comparison with the North European populations, hopefully based also on molecular data.

Tetranchyroderma swedmarki Rao & Ganapati, 1968

Records from India. ANDHRA PRADESH: Visakhapatnam (Waltair)—Rao & Ganapati (1968a); GENERAL RECORD: Naidu & Rao (2004). Habitat. Marine; substrate with sand particles of 250–400 µm 20 cm below surface.

504 · Zootaxa 4545 (4) © 2019 Magnolia Press CHATTERJEE ET AL. Distribution. India (Bay of Bengal). Remarks. Nomenclature and functional role of the accessory reproductive organs as indicated for the Indian specimens should be revised in light of the recent literature (e.g., Kieneke & Schmidt-Rhaesa 2015).

Tetranchyroderma tentaculatum Rao, 1993

Records from India. ANDAMAN & NICOBAR ISLANDS: West Bay, Little Andaman—Rao (1993); GENERAL RECORD: Naidu & Rao (2004). Habitat. Marine, intertidal; medium sand with a little detritus, 10 cm below surface, near half-tide level. Distribution. India (Bay of Bengal). Remarks. Hummon & Todaro (2010) changed the species name ending from T. tentaculata to T. tentaculatum according to the genus gender.

Genus Thaumastoderma Remane, 1926

This genus consists of 18 species (WoRMS 2018) of which only one species has been recorded from India.

Thaumastoderma heideri Remane, 1926

Records from India. ANDHRA PRADESH: Visakhapatnam (Waltair)—Ganapati & Rao (1967), Rao & Ganapati (1968b); ODISHA: Puri, Gopalpur, Bahuda estuary—Rao (1969, 1989); ANDAMAN & NICOBAR ISLANDS— Hut Bay, Little Andaman, South Bay—Rao (1975, 1980b, 1993); LAKSHADWEEP—Kavaratti, Minicoy—Rao (1991); WEST BENGAL: Medinipur, South 24 Parganas—Sanyal et al. (2012); GENERAL RECORD: Rao (1972), Naidu & Rao (2004), Rao (2005). Habitat (as in Indian records). Marine, intertidal; medium sand with little organic detritus, 5–25 cm below surface near mid-water level. Distribution. Originally described from Kieler Bucht, (Germany), the species has been subsequently recorded from several areas and localities including, North Europe, British islands, Mediterranean sea, Atlantic and Gulf coast of the USA, Maldives and India. Remarks. According to the literature, the species appears to be eurytopic, having been found at different depths and in sediments of various grain sizes. The wide distribution, the variety of habitats, and descriptions sometimes discordant, call for a better comparison of the geographic populations; hopefully based also on molecular data.

Family Turbanellidae Remane, 1925, sensu Hummon, 1982

Genus Paraturbanella Remane, 1927

Paraturbanella boadeni Rao & Ganapati, 1968

Records from India. ANDHRA PRADESH: Visakhapatnam (Waltair)—Rao & Ganapati (1968a); ODISHA (Orissa): Gopalpur—Rao (1989); ANDAMAN & NICOBAR ISLANDS: Rangat, Middle Andaman—Rao (1975, 1980b); GENERAL RECORD: Naidu & Rao (2004). Habitat. Marine, intertidal; fine and medium sand with detritus, 10–40 cm below surface, near low water level. Distribution. India (Bay of Bengal). Remarks. A recent key to species of the genus Paraturbanella has been provided by Dal Zotto et al. (2018). A redescription of the Indian species based on new material is advisable because the arrangement of the anterior adhesive tubes, as reported in the original description and drawings, appears very different from the usual layout, and the description of the male reproductive apparatus is scanty.

= Paraturbanella brevicaudatus

Records from India. LAKSHADWEEP: Kavaratti—Rao (1991); GENERAL RECORD: Naidu & Rao (2004). Habitat. Marine, intertidal; coarse and medium coralline sand, 10 cm below surface between low and mid water levels. Distribution. India (Arabian Sea). Remarks. A redescription of the female and male apparatus of this species is necessary as in the earlier descriptions, the female gonad is reported to be single rather than paired as it is the rule in the genus, and the important information regarding the lay-out of the sperm ducts and the position of the male pore is missing. Turbanellids have a relatively limited number of morphological characteristics and lack sclerotized structures useful for accurate species discrimination; moreover, some traits (e.g., number of adhesive tubes) may vary according to the age and size of the individuals. As a consequence, misidentifications are likely to occur more frequently in this family than in others. Recent works on Turbanellidae have found the lay-out of the sperm ducts and the position of the male pore to be traits constant within a species and consequently more useful than other characters for species identification/discrimination (e.g., Todaro et al. 2017; Dal Zotto et al. 2018). Therefore, we recommend future descriptions to include such information.

Paraturbanella mesoptera Rao, 1970

Records from India. ANDHRA PRADESH: Visakhapatnam (Waltair)—Rao (1970); ODISHA (Orissa): Bahuda estuary—Rao (1989); WEST BENGAL: Medinipur,—Sanyal et al. (2012); GENERAL RECORD: Naidu & Rao (2004). Habitat.Marine, intertidal; medium sand with fine shell gravel and little detritus, between low and half tide levels. Distribution. India (Bay of Bengal). Remarks. A redescription of the male apparatus of this species is advisable because in the current descriptions information regarding lay out of the sperm ducts and the position of the male pore is missing.

Paraturbanella palpibara Rao & Ganapati, 1968

Records from India. ANDHRA PRADESH: Visakhapatnam (Waltair)—Rao & Ganapati (1968a); ANDAMAN & NICOBAR ISLANDS: Rao (1989); GENERAL RECORD: Naidu & Rao (2004). Habitat. Marine, intertidal; coarse shell gravel between low and mid water levels. Distribution. India (Bay of Bengal). Remarks. A redescription of this species based on new material is advisable because the arrangement of the anterior adhesive tubes, as reported in the original description and drawings, appear very different from the usual layout, and the description of the male reproductive apparatus is incomplete.

Genus Turbanella Schultze, 1853

Turbanella aminensis Rao, 1991

Records from India. LAKSHADWEEP: Amini—Rao (1991); GENERAL RECORD: Naidu & Rao (2004). Habitat. Marine, intertidal; medium coralline sand with little detritus, 10 cm below surface between low and half tide levels. Distribution. India (Arabian Sea). Remarks. Description of the male apparatus appears incomplete as information regarding lay out of the sperm ducts and the position of the male pore is missing.

Records from India. ANDHRA PRADESH: Visakhapatnam (Waltair)—Rao & Ganapati (1968a); ODISHA (Orissa): Puri, Gopalpur, Bahuda estuary—Rao (1969, 1989); GENERAL RECORD: Naidu & Rao (2004). Habitat. Marine, intertidal; medium sand 5–15 cm below surface between low and half tide levels. Distribution. India (Bay of Bengal). Remarks. As for the previous species, information regarding the lay-out of the sperm ducts and the position of the male pore is missing.

Turbanella indica Rao, 1981

Records from India. ODISHA (Orissa): Gopalpur—Rao (1981a); GENERAL RECORD: Naidu & Rao (2004). Habitat. Marine, intertidal; medium sand 10–20 cm below surface near half-tide level. Distribution. India (Bay of Bengal). Remarks. Also for this species information regarding the lay-out of the sperm ducts and the position of the male pore is missing.

Discussion

India has 29 States and seven Union Territories of which nine States (Gujarat, Maharashtra, Goa, Karnataka, Kerala, Tamil Nadu, Andhra Pradesh, Odisha and West Bengal) and 4 Union Territories (Daman & Diu, Puducherry, Andaman & Nicobar islands and Lakshadweep) have coastal areas. But as the review shows, macrodasyidan gastrotrichs are only known from 4 States (West Bengal, Odisha, Andhra Pradesh and Kerala) and two Union Territories (Andaman & Nicobar islands and Lakshadweep, both island territories). From these, a total of 43 species have been recorded, of which two Paradasys lineatus Rao, 1980 recorded from Orissa and Andhra Pradesh (Rao, 1980) and Macrodasys indicus Govindankutty & Nair, 1969 recorded from Kerala (Govindakutty & Nair 1969), are declared as species inquirendae. Indian records of two additional species, Tetranchyroderma hystrix Remane, 1926 and Tetranchyroderma massiliense Swedmark, 1956 reported from Kerala (Govindankutty & Nair 1969; Rajan & Nair 1979) are very doubtful and should be considered as such in comprehensive biogeographic studies, which means that these species not be included among the fauna of the Indian region until proper evidence is found. Many potential good species require detailed (re)descriptions (e.g., Turbanella aminensis, Turbanella bengalensis, etc) to comply with current taxonomic standards and to allow for better comparisons among geographic populations. In conclusion, we expect further sampling of the Indian coastline to reveal more species and improve the quality of redescriptions of known species (topotypes). We also recommend the use of molecular sequence data for species verification (based on GenBank comparisons) and to reveal the presence of cryptic complexes (e.g., Kieneke & Nikoukar 2017; Kieneke et al. 2012).

Acknowledgements

We are extremely grateful to two anonymous referees for their careful revision of the manuscript and for their comments which greatly improved the readability of our article.

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