Birdsongichthys, Tornabene & Manning & Robertson & Van Tassell & Baldwin, 2023

Tornabene, Luke, Manning, Rachel, Robertson, D. Ross, Van Tassell, James L. & Baldwin, Carole C., 2023, A new lineage of deep-reef gobies from the Caribbean, including two new species and one new genus (Teleostei: Gobiidae: Gobiosomatini), Zoological Journal of the Linnean Society 197 (2), pp. 322-343 : 327-328

BIRDSONGICHTHYS GEN. NOV.

Type species: Birdsongichthys rectus sp. nov.

Zoobank registration: urn: lsid: zoobank. org:act: 287F2C89-6296-4FCB-B7B3-ED7B4B4EE73C

Diagnosis: Possesses all taxonomic characters present in most members of the Gobiosomatini and the Gobiosoma group, including the following: first dorsal-fin spines VII; dorsal pterygiophore insertion pattern 3-221110; vertebrae 27–11 precaudal and 16 caudal; hypurals 1 and 2 fused to some extent with hypurals 3 and 4 and the terminal vertebral element; one epural; ventral postcleithrum absent. Pelvic fins separate, anterior frenum connecting spines absent, membrane connecting innermost rays absent or weakly developed; pelvic-fin rays 1–5 unbranched and without fleshy or flattened tips; pelvic-fin rays long, extending posteriorly to a point between middle or end of anal fin; side of body covered with ctenoid scales, including two modified basicaudal scales; two anal-fin pterygiophores inserted before first haemal spine; cephalic sensory canals present; second dorsal-fin rays I,9; anal-fin rays I,8; body with three horizontal series of bright yellow spots, one along dorsal midline, one along lateral midline and one along ventral midline; anterior profile of head with gradual slope, not blunt or nearly vertical; eye large (~8.3–10.6% SL).

Etymology: The name honours Dr Ray S. Birdsong, who contributed substantially to the knowledge on the systematics of the family Gobiidae , especially taxa from the tropical western Atlantic and eastern Pacific Oceans. The root ‘ichthys’ is derived from the Greek ‘ ikhthús ’ (ιχθύς), fish.

Comparisons ( Table 1 ): The presence of VII dorsal spines, 11 + 16 vertebrae and a 3-221110 dorsal pterygiophore pattern ( Fig. 4A ) all support placement of Birdsongichthys in Gobiosomatini . Gobiosomatini include two main clades, the Microgobius group and the Gobiosoma group. Birdsongichthys shares several characters with genera of the Microgobius group ( Antilligobius , Akko Birdsong & Robins, 1995 , Bollmannia Jordan, 1890 , Microgobius Poey, 1876 , Palatogobius and Parrella Ginsburg, 1938 ), including a laterally compressed body and no substantial fusion between hypurals 3–4 and hypurals 1–2 and the terminal vertebral element. It differs from all Microgobius group genera in having modified basicaudal scales (absent in the Microgobius group) and in having a truncate or emarginate caudal fin (vs. lanceolate in the Microgobius group). The Gobiosoma group contains four lineages: the Barbulifer subgroup, the Nes subgroup, Aboma Jordan & Starks, 1895 and Robinsichthys . Birdsongichthys can be distinguished from all members of the Barbulifer subgroup ( Aruma Ginsburg, 1933 , Barbulifer , Elacatinus Jordan, 1904 , Evermannichthys Metzelaar, 1919 , Ginsburgellus Böhlke & Robins, 1968 , Gobiosoma , Ophiogobius Hoese, 1976 , Pariah Böhlke, 1969 , Risor Ginsburg, 1933 and Tigrigobius Fowler, 1931 ) and Aboma by its completely separate pelvic fins that lack an anterior frenum and have unbranched rays; the Barbulifer subgroup and Aboma have pelvic fins united to form a complete disc with branched rays. Completely separate pelvic fins also characterize species in the Nes subgroup, except Nes and Gobulus . Birdsongichthys differs from most genera of the Nes subgroup and from Robinsichthys in having cephalic lateralis canals and associated head pores. Among Nes subgroup genera, only Eleotrica Ginsburg, 1933 , Gymneleotris Bleeker, 1874 , and two species of Chriolepis Gilbert, 1892 possess head pores. Birdsongichthys has unbranched pelvic-fin rays, whereas these three genera all have branched pelvicfin rays. The only Gobiosomatini genera containing species with completely unbranched pelvic-fin rays are the monotypic Paedovaricus Van Tassell et al., 2016 [ P. imswe (Greenfield, 1981) ] and Varicus (unbranched in specimens of five of ten known species in the genus). Birdsongichthys differs from these two genera in having two (vs. one) anal-fin pterygiophores inserted anterior to the first haemal spine. Finally, Birdsongichthys can be further distinguished from Robinsichthys in having 11 + 16 vertebrae (vs. 11 + 17).

Figures

Figure 4. Vertebrae and pterygiophore insertion patterns for: A, Birdsongichthys rectus gen. nov., sp. nov., 3-221110 pattern, paratype UW 158074, cleared and stained; B, Robinsichthys nigrimarginatus sp. nov., 3-22111*0 pattern, holotype, USNM 446953, micro-CT-scan. *Indicates pterygiophore without associated dorsal-fin spine.