Systematics of Amblyopinae

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former has a limited distribution, extending across northern Australia from the Prince Regent River to the Gulf of Carpentaria whereas the latter is known from the ...


1.8 Systematics of Amblyopinae Edward Murdy

Gobies of the gobiid subfamily Amblyopinae are elongate, mud-dwelling fishes of the Indo-West Pacific region that are commonly referred to as “eel gobies” or “worm gobies”. Currently, 12 genera and 23 species of Amblyopinae are recognized. In life, these gobies are pink, purple, or red (Fig. 1.8.1). In contrast to the majority of gobies, amblyopine gobies have a continuous dorsal fin; the spinous (first) and soft (second) dorsal fins are connected by membrane. Because they live in turbid water habitats, the eyes of amblyopines are reduced in size and may have limited function. Based on axial skeletal features, Birdsong et al. (1988) subdivided the Amblyopinae into three units: ‘Gobioides’ Group, ‘Taenioides’ Group, and ‘Trypauchen’ Group. Birdsong et al. (1988) stated that the latter two groups shared the derived fin element to vertebra ratio of 2:1 whereas the ‘Gobioides’ Group possessed a ratio of 1:1 as is typical amongst gobioids. Subsequently, other characters have been found to ally the ‘Gobioides’ Group, comprising only Gobioides, with the Gobionellinae (Harrison, 1989; Pezold, 1993; Murdy, 1998). Murdy and Shibukawa (2001, 2002) recognized the following

Author’s address: National Science Foundation, 4201 Wilson Blvd., Arlington, VA 22230, USA. E-mail: [email protected]


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two features as synapomorphies for the monophyletic Amblyopinae (i.e. ‘Taenioides’ Group + ‘Trypauchen’ Group): fin element to vertebra ratio of 2:1; and ultimate dorsal- and anal-fin pterygiophores supporting only a single ray.

Fig. 1.8.1 Caragobius rubristriatus snagged on a fishing lure in Northern Territory, Australia, displaying the pinkish coloration common to many amblyopines. (Image by T. Robb and provided courtesy of M. McGrouther, Australian Museum). Color image of this figure appears in the color plate section at the end of the book.

Birdsong et al. (1988) created the ‘Trypauchen’ Group as a putative monophyletic assemblage. All members of the ‘Trypauchen’ Group lack an interneural gap (space between neural arches lacking a pterygiophore), which is a synapomorphy amongst gobiid fishes; the ‘Trypauchen’ Group dorsalfin pterygiophore formula is 3-1221 (= 3/I II II I/7·8 in Akihito et al. 1984). Birdsong et al. (1988) assigned all the remaining gobiid genera sharing the fin element to vertebra ratio of 2:1 to the ‘Taenioides’ Group, which is a phenetically united assemblage.

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The ‘Taenioides’ Group of the Amblyopinae listed in Birdsong et al. (1988) comprised Brachyamblyopus, Odontamblyopus, and Taenioides. This group was phenetically united by the shared possession of a spinous dorsal-fin pterygiophore formula of 3-12210. To this group, Murdy and Shibukawa (2002) added Pseudotrypauchen. Pseudotrypauchen differs from the other group members and all other amblyopines by having the first two pterygiophores of the second dorsal fin (D2) separated by a neural spine (one pterygiophore resides in interneural space 8 and the other in interneural space 9) (Fig. 1.8.2). All other amblyopines have the first two pterygiophores of the second dorsal fin sharing the same interneural space (interneural space 7 or 8) (Fig. 1.8.3). The condition of the first two pterygiophores of the second dorsal fin in Pseudotrypauchen is considered the gobiid type of D2 anterior pterygiophore arrangement, whereas the condition shown by all other amblyopines is the eleotrid type of D2 anterior pterygiophore arrangement (gobiid and eleotrid types of ‘interneural gap’ of Hoese 1984). As the Oxudercinae has the gobiid type of D2 anterior pterygiophore arrangement and is considered the putative sister group to the Amblyopinae (Murdy and Shibukawa, 2001), the eleotrid type of D2 anterior pterygiophore arrangement is a reversal and is, thus, derived according to Murdy and Shibukawa (2002). With respect to the polarity of the D2 anterior pterygiophore arrangement in Pseudotrypauchen, Murdy and Shibukawa (2002) stated that it is primitive. As such, Pseudotrypauchen represents the basal member within the subfamily and is the sister group to all other amblyopines. (Thacker (2003) disputed a sister group relationship between the Oxudercinae and the Amblyopinae.)

Fig. 1.8.2 Left lateral view of a radiograph of Pseudotrypauchen multiradiatus (USNM 341061) showing the first two pterygiophores of the second dorsal fin separated by a neural spine (gobiid type of D2 anterior pterygiophore arrangement). This is the typical condition in non-amblyopine gobies.


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Fig. 1.8.3 Left lateral view of a radiograph of the holotype of Brachyamblyopus brachysoma (RMNH 4670) showing the first two pterygiophores of the second dorsal fin sharing the same interneural space (eleotrid type of D2 anterior pterygiophore arrangement). This is the typical condition in amblyopine gobies.

THE ‘TAENIOIDES’ GROUP Pseudotrypauchen comprises a single species (P. multiradiatus) known from India, Malaysia, and Sumatra. The genus is unique within the Amblyopinae in having: pectoral fins longer than pelvic fins (113–205% of pelvic-fin length) and pointed posteriorly; short, compressed, and gently rounded teeth in the outermost tooth row in both jaws; and in having the first two pterygiophores of the second dorsal fin separated by a neural spine (Murdy and Shibukawa, 2002). Meristic counts are included in Table 1.8.1. Table 1.8.1 Means and ranges of dorsal- and anal-fin elements in the Amblyopinae. Counts for dorsal- and anal-fins include all elements. Genus Amblyotrypauchen Brachyamblyopus Caragobius Ctenotrypauchen Gymnoamblyopus Karsten Odontamblyopus Paratrypauchen Pseudotrypauchen Taenioides Trypauchen Trypauchenichthys Trypauchenopsis

Dorsal Fin Elements range 48 35 36 53

– 52 – 39 – 52 – 57 33 46 – 51 40 – 54 50 – 60 36 – 39 41 – 66 46 – 58 45 – 48, 58 – 62 33 – 42

Anal Fin Elements range 39 28 31 41

– 43 – 34 – 45 – 46 26 40 – 44 32 – 45 41 – 49 30 – 32 34 – 65 39 – 50 37 – 39, 46 – 52 27 – 33

Vertebral Count range 9 – 10 + 19, 23 10 + 16 10 + 18 – 22, 25 – 27 10 + 23 – 25 10 + 16 9 + 19 – 22 10 + 17, 20 – 24 10 + 25 – 28 10 + 17 10 + 17 – 23 10 + 19 – 20, 23 – 24 10 + 31 – 32, 35 – 36, 40 – 41 10 + 16 – 18

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Brachyamblyopus is little known and, thus, little studied. The holotype of B. brachysoma was collected in Sumatra and the species is also reported from Sulawesi, Papua New Guinea, the Persian Gulf, India, Thailand, and Hong Kong (Koumans, 1953). Brachyamblyopus brachysoma has a scaleless head, an enlarged, outer row of teeth in the jaws, and lacks head barbels (Murdy and Shibukawa, 2001). Odontamblyopus comprises five species distributed from the west coast of India to northern China and Japan (Murdy and Shibukawa, 2001; Murdy and Shibukawa, 2003). Odontamblyopus has numerous fang-like teeth and shares with Pseudotrypauchen the condition of having the pectoral-fin rays free and silk-like. O. lacepedii is a marine and brackish-water goby that creates elaborate burrows in mud. Its burrows are tunnel-shaped, vertical, and extend to depths of 90 cm into the substrate; as many as six other smaller tunnels radiate from the primary tunnel and connect to the surface (Gonzales et al. 2008). According to Dotsu (1957), this species eats a variety of foods including bivalves, crustaceans, cephalopods, and small fishes. At low tide, this fish is a facultative air breather (Gonzales et al. 2006). The genus Taenioides is in need of revision (Murdy and Randall, 2003). Taenioides is diagnosed amongst Gobiidae by the proximal radial of anterior second anal-fin pterygiophore being spatulate (this is equivalent to the Y-shaped, second anal-fin pterygiophore described by Birdsong et al. 1988). Taenioides spp. have raised dermal ridges bearing sensory papillae on the head and body as well as barbels on the underside of the head arranged in several different patterns (Fig. 1.8.4). The genus is distributed from the east coast of Africa, Arabian Gulf, throughout southeast Asia, Australia, China, and Japan.

Fig. 1.8.4 Taenioides snyderi Jordan and Hubbs (1925). Originally figured as Taenioides lacepedei in Jordan and Snyder (1901).


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Trypauchenopsis intermedia (Fig. 1.8.5) is known by the common name of bearded eel goby due to the presence of many barbel-like projections on the head. This taxon is characterized by the ultimate fin ray in either the dorsal or anal fins (or both) bearing a forked pterygiophore, the middle radial of which is bifurcated such that the proximal radial adjoins one hemal (or neural) spine and the bifurcated arm adjoins the hemal (or neural) spine posterior to it. This species has a very broad distribution from South Africa to Guam.

Fig. 1.8.5 Trypauchenopsis intermedia, SAIAB 14127, 106 mm SL, Mkomazi, Natal, South Africa. Figure drawn by D.P. Voorvelt of the J.L.B. Smith Institute and provided courtesy of E. Heemstra and J. Stapley.

The monotypic Gymnoamblyopus is the most recent addition to the ‘Taenioides’ Group (Murdy and Ferraris, 2003) and is known only from a single specimen collected in Fly River, Papua New Guinea. It differs from all other amblyopine gobies by the following combination of characters: only one anal-fin pterygiophore anterior to first hemal spine; no spatulate second anal-fin pterygiophore; no chin barbels; no scales; no raised dermal folds or ridges; pleural ribs short and posteriorly directed; and mouth vertical.

‘Taenioides’ Group Genus Genus Genus

Brachyamblyopus Bleeker, 1874 Brachyamblyopus brachysoma Bleeker, 1874 Gymnoamblyopus Murdy and Ferraris, 2003 Gymnoamblyopus novaeguinea Murdy and Ferraris, 2003 Odontamblyopus Bleeker, 1874 Odontamblyopus lacepedii (Temminck and Schlegel, 1845) Odontamblyopus rebecca Murdy and Shibukawa, 2003 Odontamblyopus roseus (Valenciennes, 1837)

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Odontamblyopus rubicundus (Hamilton-Buchanan, 1822) Odontamblyopus tenuis (Day, 1876) Genus Taenioides Lacepède, 1800 At least the following four species are considered valid: Taenioides anguillaris (Linnaeus, 1758) Taenioides gracilis (Valenciennes, 1837) Taenioides kentalleni Murdy and Randall, 2002 Taenioides purpurascens De Vis, 1884 Genus Trypauchenopsis Volz, 1903 Trypauchenopsis intermedia (Volz, 1903) The above listing of the ‘Taenioides’ Group comprises five genera and 12 species. In addition, two new genera await description. These new genera include at least three described species.

THE ‘TRYPAUCHEN’ GROUP Among ‘Trypauchen’ Group members (Amblyotrypauchen, Caragobius, Ctenotr y pauchen, Karsten, Paratr y pauchen, Tr y pauchen, and Trypauchenichthys), all but Caragobius and Karsten possess a shallow pouch along the dorsal edge of the operculum (Fig. 1.8.6); the function of this opercular pouch is not known. In addition, all ‘Trypauchen’ Group members except Karsten have a pterygiophore formula of 3-1221 that is unique within the Gobioidei (Birdsong et al. 1988). Murdy (2002) proposed Caragobius as the sister group to all other ‘Trypauchen’ Group members and Karsten as the sister group to all ‘Trypauchen’ Group members that possess an opercular pouch.

Fig. 1.8.6 Approximate relative size and location of the opercular pouch in those amblyopine gobies that possess one. (Modified from figure 313 in Kottelat et al., 1993.)


The Biology of Gobies

Caragobius comprises two species, C. rubristriatus and C. urolepis; the former has a limited distribution, extending across northern Australia from the Prince Regent River to the Gulf of Carpentaria whereas the latter is known from the east coast of India eastward to Fiji. Caragobius is unique within the Amblyopinae in having: 3-7 anal-fin pterygiophores anterior to first hemal spine (AP); fifth hypural absent; and ribs lacking on 3rd precaudal vertebra. The other features useful in distinguishing it from all other ‘Trypauchen’ Group members are: pectoral fins broadly rounded, symmetrical dorsoventrally; head slightly depressed; no fang-like teeth; no opercular pouch; eyes rudimentary; and pelvic fins rounded (Murdy and Shibukawa, 2003). The monotypic Karsten is distinguished from all other members of the subfamily in having a spinous dorsal-fin pterygiophore formula of 3 – 123, 3 – 132, or 3 – 1221 + 2. The genus is also distinct within the subfamily in having only nine precaudal vertebrae. Karsten lacks eyes as does Amblyotrypauchen. Of special note, one lot of Karsten (K. totoyensis, USNM 113201) was collected at a depth of 608 fathoms (1122 m) over a mud/sand bottom; this may represent the greatest depth from which any goby has ever been collected (Murdy, 2002). Karsten has only been collected from Indonesia, the Philippines, and Fiji. Amblyotrypauchen is unique within the Amblyopinae in having 10+19 vertebrae, enlarged fang-like teeth in both jaws, partially separate pelvic fins, and scale patches on the opercle, cheeks, and dorsum of head. Amblyotrypauchen lacks eyes and has been collected off muddy bottoms from almost 17 m to over 183 m in depth. Amblyotrypauchen comprises a single species, A. arctocephalus, known from India, Malaysia, Hong Kong, the Philippines, Papua New Guinea, and Australia (Murdy, 2003). Trypauchen is unique within the Amblyopinae in having the following combination of characters: 1) typically four, rarely three, anal-fin pterygiophores anterior to the first hemal spine; 2) pelvic fins small, united, and funnel-shaped with a well-developed interradial membrane; and 3) abdomen scaled. Trypauchen comprises two species: T. pelaeos, known from Myanmar, Malaysia, Thailand, Vietnam, and China; and T. vagina, distributed from Kuwait, along the coasts of India, ranging eastward to the Philippines, Taiwan, and China (Murdy, 2006). The monotypic Paratrypauchen differs from Trypauchen in having a scaleless abdomen, emarginate pelvic fins, and in having three pterygiophores anterior to the first hemal spine (Murdy, 2008a). Akihito et al. (1984) reported that in Japan Paratrypauchen microcephalus inhabits soft mud bottoms (Fig. 1.8.7). Chen and Fang (1999) stated that P. microcephalus inhabits river mouth areas near mangrove forests and constructs burrows

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in the muddy substrate. This species is an omnivore feeding on benthic invertebrates such as crustaceans according to Chen and Fang (1999). Paratrypauchen microcephalus is known from Japan, Taiwan, the Philippines, Australia, Singapore, Malaysia, Vietnam, India, Mozambique, and South Africa. This species is one of the more common amblyopines in museum collections.

Fig. 1.8.7 Trypauchen wakae (= Paratrypauchen microcephalus) from Jordan and Snyder (1901).

Ctenotrypauchen is unique within the ‘Trypauchen’ Group in having a serrated frontal crest with united, but slightly emarginate pelvic fins. A specimen of Ctenotrypauchen chinensis from the Arafura Sea was collected at a depth of 62-65 meters. Based on the few specimens that exist in collections, it appears that this taxon may be confined to deeper waters than most other members of this subfamily excluding Amblyotrypauchen and Karsten. Trypauchenichthys is unique within the Amblyopinae in having the pelvic fins separate (not joined by a connecting membrane) (Fig. 1.8.8). Trypauchenichthys comprises three species: T. larsonae known only from the Northern Territory, Australia; T. sumatrensis found in the Strait of Malacca with a reported occurrence in India (Fig. 1.8.9), and T. typus with specimens known only from the type locality in western Borneo and reports from Thailand, the Philippines, Sarawak, and the Riau Archipelago, Indonesia (Murdy, 2008b).

Fig. 1.8.8 Pelvic fin shapes of ‘Trypauchen’ group genera (modified from Hora, 1924).


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Fig. 1.8.9 Trypauchenichthys sumatrensis (drawn from a specimen removed from USNM 211295). The bony frontal crest is evident. Drawing by Christine Baer.

‘Trypauchen’ Group Genus Genus

Genus Genus Genus Genus


Amblyotrypauchen Hora, 1924 Amblyotrypauchen arctocephalus (Alcock, 1890) Caragobius Smith and Seale, 1906 Caragobius rubristriatus (Saville-Kent, 1889) Caragobius urolepis (Bleeker, 1852) Ctenotrypauchen Steindachner, 1867 Ctenotrypauchen chinensis Steindachner, 1867 Karsten Murdy, 2002 Karsten totoyensis (Garman, 1903) Paratrypauchen Murdy, 2008 Paratrypauchen microcephalus (Bleeker, 1860) Trypauchen Valenciennes, 1837 Trypauchen pelaeos Murdy, 2006 Trypauchen vagina (Bloch and Schneider, 1801) Trypauchenichthys Bleeker, 1860 Trypauchenichthys larsonae Murdy, 2008 Trypauchenichthys sumatrensis Hardenberg, 1931 Trypauchenichthys typus Bleeker, 1860

References Akihito, Prince, M. Hayashi, T. Yoshino, K. Shimada and H. Senou. 1984. Suborder Gobioidei. In: The Fishes of the Japanese Archipelago, H. Masuda, K. Amaoka, C. Araga, T. Uyeno and T. Yoshino (eds.). Tokai University Press, Tokyo, pp. 236-238 and plates 235-258, 353-355.

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Birdsong, R.S., E.O. Murdy and F.L. Pezold. 1988. A study of the vertebral column and median fin osteology in gobioid fishes with comments on gobioid relationships. Bulletin of Marine Science 42: 174-214. Chen, I.-S. and L.-S Fang. 1999. The Freshwater and Estuarine Fishes of Taiwan. National Museum of Marine Biology and Aquarium, Pingtung. (In Chinese). Dotsu, Y. 1957. On the bionomics and life history of the eel-like goby, Odontamblyopus rubicundus (Hamilton). Science Bulletin of the Faculty of Agriculture, Kyushu University 16: 101-110. Gonzales, T.T., M. Katoh and A. Ishimatsu. 2006. Air-breathing of aquatic burrowdwelling eel goby, Odontamblyopus lacepedii (Gobiidae: Amblyopinae). Journal of Experimental Biology 209: 1085-1092. Gonzales, T.T., M. Katoh and A. Ishimatsu. 2008. Intertidal burrows of the airbreathing eel goby, Odontamblyopus lacepedii (Gobiidae: Amblyopinae). Ichthyological Research 55: 303-306. Harrison, I.J. 1989. Specialization of the gobioid palatopterygoquadrate complex and its relevance to gobioid systematics. Journal of Natural History 23: 325353. Hoese, D.F. 1984. Gobioidei: Relationships. In: Ontogeny and Systematic of Fishes. H.G. Moser, W.J. Richards, D.M. Cohen, M.P. Fahay, A.K. Kendall, Jr. and S.L. Richardson (eds.), Allen Press, Lawrence, pp. 588-591. Hora, S.L. 1924. Notes on fishes in the Indian Museum. VI. On a new genus of gobioid fishes (subfamily Trypaucheninae) with notes on related forms. Records of the Indian Museum, Calcutta 26: 155-163. Jordan, D.S. and J.O. Snyder. 1901. A review of the gobioid fishes of Japan, with descriptions of twenty-one new species. Proceedings of the United States National Museum 24: 33-132. Jordan, D.S. and C.L. Hubbs. 1925. Records of fishes obtained by David Starr Jordan in Japan, 1922. Memoirs of the Carnegie Museum 10: 93-346. Kottelat, M., A.J. Whitten, S.N. Kartikasari and S. Wirjoatmodjo. 1993. Freshwater Fishes of Western Indonesia and Sulawesi. Wildlife Heritage Trust of Sri Lanka, Colombo. Koumans, F.P. 1953. Gobioidea. In: Fishes of the Indo-Australian Archipelago, M. Weber and L.F. de Beaufort (eds.). E.J. Brill, Leiden, pp. 1-423. Murdy, E.O. 1998. A review of the gobioid fish genus Gobioides. Ichthyological Research 45: 9-21. Murdy, E.O. 2002. Karsten, a new genus of eel goby (Gobiidae: Amblyopinae) with a key to “Trypauchen” group genera. Copeia 2002(3): 787-791. Murdy, E.O. 2003. A review of Amblyotrypauchen (Teleostei: Gobiidae), a genus of blind amblyopine gobies. Proceedings of the Biological Society of Washington 116: 330-336. Murdy, E.O. 2006. A revision of the gobiid fish genus Trypauchen (Gobiidae: Amblyopinae). Zootaxa 1343: 55-68. Murdy, E.O. 2008a. Paratrypauchen, a new genus for Trypauchen microcephalus Bleeker 1860 (Perciformes: Gobiidae: Amblyopinae) with redescription of


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Ctenotrypauchen chinensis Steindachner 1867. aqua, International Journal of Ichthyology 14: 115-128. Murdy, E.O. 2008b. Trypauchenichthys larsonae, a new species of amblyopine goby from Australia (Gobiidae: Amblyopinae) with a key to the species in the genus. aqua, International Journal of Ichthyology 14: 59-68. Murdy, E.O. and K. Shibukawa. 2001. A revision of the gobioid fish genus Odontamblyopus (Gobiidae: Amblyopinae). Ichthyological Research 48: 31-43. Murdy, E.O. and K. Shibukawa. 2002. A redescription of the gobiid fish genus Pseudotrypauchen (Gobiidae: Amblyopinae) and its significance in amblyopine phylogeny. Marine and Freshwater Research 53: 253-258. Murdy, E.O. and C.J. Ferraris, Jr. 2003. Gymnoamblyopus novaeguineae, a new genus and species of worm goby from Papua New Guinea (Gobiidae: Amblyopinae). Zootaxa 150: 1-6. Murdy, E.O. and J.E. Randall. 2003. Taenioides kentalleni, a new species of eel goby from Saudi Arabia (Gobiidae: Amblyopinae) Zootaxa 93: 1-6. Murdy, E.O. and K. Shibukawa. 2003. A revision of the Indo-Pacific fish genus Caragobius (Gobiidae: Amblyopinae) Zootaxa 301: 1-12. Pezold, F. 1993. Evidence for a monophyletic Gobiinae. Copeia 1993(3): 634-643. Thacker, C.E. 2003. Molecular phylogeny of the gobioid fishes (Teleostei: Perciformes: Gobioidei). Molecular Phylogenetics and Evolution 26: 354-368.