Friday, June 10, 2016

[Ichthyology • 2016] Molecular Phylogeny, Analysis of Character Evolution, and Submersible Collections Enable A New Classification of A Diverse Group of Gobies (Gobiidae: Nes Subgroup), including Nine New Species and Four New Genera

Psilotris laurae, Pinnichthys saurimimica, Varicus decorum, Psilotris laetarii, Varicus veliguttatus, Varicus adamsi, Varicus cephalocellatus, Pinnichthys aimoriensis & Varicus nigritus

Tornabene, Van Tassell, Gilmore, Robertson, Young & Baldwin. 2016.  DOI:  10.1111/zoj.12394  

The Nes subgroup of the Gobiosomatini (Teleostei: Gobiiformes: Gobiidae) is an ecologically diverse clade of fishes endemic to the tropical western Atlantic and eastern Pacific oceans. It has been suggested that morphological characters in gobies tend to evolve via reduction and loss associated with miniaturization, and this, coupled with the parallel evolution of adaptations to similar microhabitats, may lead to homoplasy and ultimately obscure our ability to discern phylogenetic relationships using morphological characters alone. This may be particularly true for the Nes subgroup of gobies, where several genera that are diagnosed by ‘reductive characters’ have been shown to be polyphyletic. Here we present the most comprehensive phylogeny to date of the Nes subgroup using mitochondrial and nuclear sequence data. We then evaluate the congruence between the distribution of morphological characters and our molecular tree using maximum-likelihood ancestral state reconstruction, and test for phylogenetic signal in characters using Pagel's λ tree transformations (Nature, 401, 1999 and 877). Our results indicate that all of the characters previously used to diagnose genera of the Nes subgroup display some degree of homoplasy with respect to our molecular tree; however, many characters display considerable phylogenetic signal and thus may be useful in diagnosing genera when used in combination with other characters. We present a new classification for the group in which all genera are monophyletic and in most cases diagnosed by combinations of morphological characters. The new classification includes four new genera and nine new species described here, many of which were collected from rarely sampled deep Caribbean reefs using manned submersibles. The group now contains 38 species in the genera Carrigobius gen. nov., Chriolepis, Eleotrica, Gobulus, Gymneleotris, Nes, Paedovaricus gen. nov., Pinnichthys gen. nov., Psilotris gen. nov., and Varicus. Lastly, we provide a key to all named species of the Nes subgroup along with photographs and illustrations to aid in identification.

Keywords: ancestral state reconstruction; Caribbean; coral reef fish; deep reefs; gobies; Gobiidae; systematics


• Carrigobius Van Tassell, Tornabene & Gilmore gen. nov. 
Type species: Carrigobius amblyrhyncus (Smith & Baldwin, 1999: 434, Figs 1-3, described as Psilotris amblyrhyncus

Etymology: The name Carrigobius is formed from the Latin gobius (goby or gudgeon) and Carrie, in reference to Carrie-Bow Cay, Belize, home of the Smithsonian Institution's field station, where many specimens of Carrigobius amblyrhynchus were collected.

• Chriolepis Gilbert, 1892
Type Species: Chriolepis minutilla Gilbert, 1892 (Original Spelling Chriolepis minutillus), by Monotypy 

• Pycnomma Rutter, 1904
Type Species: Pycnomma semisquamatum Rutter, 1904, by monotypy

• Cryptopsilotris Van Tassell, Tornabene & Gilmore gen. nov. 
Type Species: Cryptopsilotris batrachodes (Böhlke, 1963: 6, fig. 2, Described as Psilotris batrachodes)

Etymology: The genus name is formed from ‘Psilotris’, the genus the type species was formerly classified under, and the root ‘crypto-’, which is taken from the Greek ‘kruptos’ meaning hidden. The name is in reference to the cryptic coloration of the type species.

• Eleotrica Ginsburg, 1933
Type Species: Eleotrica cableae Ginsburg, 1933 (p. 10, by Original Designation)

• Gobulus Ginsburg, 1933
Type Species: Gobulus crescentalis (Gilbert, 1892) (Ginsburg, 1933: 12, by Original Designation)

• Gymneleotris Bleeker, 1874
Type Species: Gymneleotris seminudus (Günther, 1864: 304, Described as Eleotris seminudus Günther, 1864, by Original Designation)

• Nes Ginsburg, 1933
Type Species: Nes longus (Nichols, 1914) (Ginsburg, 1933: 25, Described as Gobiosoma longum Nichols, 1914, by Original Designation; Proposed as a Subgenus of Gobiosoma)

• Paedovaricus Van Tassell, Tornabene & Gilmore gen. nov. 
Type Species: Paedovaricus imswe (Greenfield, 1981: 269, Described as Varicus imswe)

Etymology: The genus name Paedovaricus is formed from the root ‘paed-’ (the English spelling of the Greek root ‘ped-’, meaning ‘child’) and Varicus. The name is in reference to the small size of the type species Paedovaricus imswe and its general similarity to the genus Varicus.

• Pinnichthys Van Tassell, Tornabene & Gilmore gen. nov. 
Type Species: Pinnichthys aimoriensis Van Tassell, Tornabene & Gilmore sp. nov.

Etymology: The name Pinnichthys is formed from the roots pinna (Latin, feminine; fin) and ichthys (Latinized form of the Greek acronym ichthus; fish). The name is given in reference to the high number of fin rays in the second dorsal fin and anal fin of all species in the genus.

Pinnichthys aimoriensis Van Tassell & Tornabene sp. nov.   | Thiony's Goby 

Habitat: Collected from the seafloor near the Peroá natural gas platform. The substrate was predominately rhodoliths and other calcareous substrate.

Distribution: Known only from the margin of the continental shelf of Brazil off Espírito Santo.

Etymology: The species epithet aimoriensis is an adjective formed from the proper noun Aimorés, an indigenous warrior people from the lands now belonging to the Brazilian states Espírito Santo, Bahia, and Minas Gerais. The Aimorés people were virtually extirpated by European settlers during the Aimorés War (1555–1673), and much of their native forest has been replaced by agriculture. The type locality for Pinnichthys aimoriensis gen. et sp. nov. is adjacent to the Peroá natural gas platform, and the nearby coastal region is facing rapid development from the petroleum industry and mining of rhodolith beds (carbonates) for agriculture, and may be under threat of losing biodiversity before it can be adequately studied and described. This situation is analogous to the loss of Aimorés culture and the forest biodiversity that inhabited their native lands of the Central Brazilian coast.

Pinnichthys saurimimica Gilmore, Van Tassell & Tornabene sp. nov.  | Lizardfish Goby

Habitat: Holotype was collected on a calcareous sand and dead Halimeda spp. algal rubble zone, with scattered shallow calcareous rock ledges.

Distribution: Known only from San Salvador, Bahamas, the type locality.

Etymology: The name saurimimica is derived from ‘saurus’, a genus of lizard fish and the Greek ‘mimic’, as the colour pattern closely resembles that of a lizard fish.

• Psilotris Ginsburg, 1953
Type Species: Psilotris alepis Ginsburg, 1953 (by Original Designation)

Psilotris laetarii Van Tassell & Young sp. nov.  | Burrow Splitfin Goby 

Distribution: Known only from the type series collected off the south shore of Marathon, Florida.

Etymology: Named in honor of Heath Jens Laetari, 28 years old, Vice President of Dive Operations, Partner & Acquisition Manager for Dynasty Marine, who was lost at sea on 14 September 2006, doing what he loved to do.

Psilotris laurae Van Tassell, Tornabene & Baldwin sp. nov.  | Thin-barred Goby 

Habitat: The only known specimen was found inside a glass bottle collected along a sandy slope between 114 and 137 m depth. There is no additional information on the natural microhabitat of this species.
Distribution: Known only from the type location off Bonaire.

Etymology: Named after Laura Albini, wife of Adriaan ‘Dutch’ Schrier, the owner of Substation Curaçao, through whose efforts new, tropical, deep-water species are being discovered. Laura has generously fed and hosted numerous researchers during their visits to Curaçao.

• Varicus Robins & Böhlke, 1961
Type Species: Varicus bucca Robins & Böhlke, 1961 (p. 47, Figs 1-3, by Original Designation)

Varicus adamsi Gilmore, Van Tassell & Tornabene sp. nov. | Twilight Goby 

Distribution: Known only from the western shore of San Salvador, Bahamas and from Tobago.
Etymology: Named for the late famed research submersible pilot, Mr. Michael Adams, who painstakingly captured both Bahamas specimens during a 30–45 min chase using a 26 ton submarine (JSL – II) in simultaneous multiple thrust, multi-directional mode to allow this description. Mr. Adams was one of the five original research submersible pilots within the United States.

Varicus cephalocellatus sp. nov., Gilmore, Van Tassell, and Baldwin | Ocellated Splitfin Goby

Distribution: All specimens are known from southern Lesser Antilles, St. Vincent, Barbados and Bonaire.
Etymology: Named for series of ocelli on head extending from mouth diagonally to nape.

Varicus decorum sp. nov., Van Tassell, Baldwin and Tornabene | Decorated Splitfin Goby

Habitat: This species has been collected from sand habitats with scattered rocks and calcareous rubble, from depths of 99 m to at least 197 m, and possibly 251 m. It has been observed perching on open sand and retreating into crevices when disturbed.
Distribution: Known only from deep reefs off Curaçao.
Etymology: The specific epithet decorum is Latin for “decorated”, “adorned”, “beautiful” or “elegant” and is in reference to the beautiful round yellow markings on the dorsal surface of the body.

Varicus nigritus sp. nov., Gilmore, Van Tassell, and Baldwin | Banded Splitfin Goby

Habitat: The holotype was captured off Rocky Point along the northwest shore of San Salvador, Bahama Islands on a steep rocky slope (45° slope) with thin and sparse calcareous Halimeda rubble layer mixed with scattered flat rock outcroppings, hard rock unlayment and scattered rock boulders 1–30 m in diameter.
Distribution: A single specimen captured at 243.8 m off San Salvador, Bahama Islands.

Etymology: The epithet nigritus, Latin for “black”, is given in reference to the diagnostic dark black wide bars on the trunk of this species.

Varicus veliguttatus sp. nov., Van Tassell, Baldwin and Gilmore | Spotted-sail Goby

Habitat: In the Bahamas this species was collected from oolite sedimentary rock at 287.6 m depth. In Curaçao this species was collected at depths between 152 m and 225 m, over sand habitats with rubble, gravel and shells.

Distribution: Known from San Salvador, Bahamas, Curaçao, and Tobago.

Etymology: The specific epithet veliguttatus is formed from the Latin roots veli- (sail) and guttatus (spotted or speckled). The scientific name and common name refer to the scattered black markings on the first dorsal fin.

Summary of Systematic Changes
Based on our combined analysis of molecular data from mtDNA, nuclear genes, and morphological characters, we have made the following changes in the classification of the Nes subgroup in order to render all groups monophyletic (see Table 2). We synonymize the genus Pycnomma with Chriolepis. Two Atlantic species previously belonging to Chriolepis (C. vespa and C. benthonis) are now reassigned to the genus Varicus, which now also contains five new species described here (Varicus adamsi sp. nov., Varicus cephalocellatus sp. nov., Varicus decorum sp. nov., Varicus nigritus sp. nov., Varicus veliguttatus sp. nov.). The genus Pinnichthys is erected for the new species Pinnichthys aimoriensis gen. et sp. nov., and also contains three other species formerly included in Chriolepis (C. atrimela, C. bilix, C. prolata). The new genus Paedovaricus is erected for Paedovaricus imswe (formerly Varicus imswe), and the new genus Carrigobius is erected for Carrigobius amblyrhynchus (formerly Psilotris amblyrhynchus). Chriolepis fisheri is considered incertae sedis, as its phylogenetic position is either sister to Pinnichthys, or nested within Psilotris. The latter genus now includes the two new species P. laetarii sp. nov. and P. laurae sp. nov.

Luke Tornabene, James L. Van Tassell, Richard G. Gilmore, David Ross Robertson, Forrest Young and Carole C. Baldwin. 2016. Molecular Phylogeny, Analysis of Character Evolution, and Submersible Collections Enable A New Classification of A Diverse Group of Gobies (Teleostei: Gobiidae: Nes subgroup), including Nine New Species and Four New Genera.
Zoological Journal of the Linnean Society.  DOI:  10.1111/zoj.12394