Gobiosoma Girard, 1858

Tornabene, Luke & Van Tassell, James L., 2014, Redescription of the goby genus Gobiosoma (Teleostei: Gobiidae: Gobiosomatini), with the synonymy of the genus Enypnias, Journal of Natural History 48 (23 - 24), pp. 1413-1437 : 1418-1420

Gobiosoma Girard, 1858

Gobiosoma Girard, 1858: 169 (type species Gobiosoma molestum Girard 1858 = Gobsioma bosci Lacepède1800 , by subsequent designation by Bleeker 1874: 310).

Garmannia Jordan and Evermann, in Jordan 1895: 495 (type species: Gobius paradoxus Günther 1861 , by original designation).

Gerhardinus Meek and Hildebrand, 1928: 889 (type species: Gerhardinus nudus Meek and Hildebrand 1928 , by original designation).

Dilepidion Ginsburg, 1933: 17 (type species: Gobiosoma ginsburgi Hildebrand and Schroeder 1928 )

Gobiculina Ginsburg, 1944: 380 (type species Garmannia homochroma Ginsburg 1939 , by original designation).

Gobiolepis Ginsburg, 1944: 379 (type species: Garmannia hildebrandi Ginsburg 1939 , by original designation).

Gobiohelpis Ginsburg, 1944: 380 (type species: Garmannia spes Ginsburg 1939 , by original designation).

Austrogobius de Buen, 1950: 122 (name introduced); 1951: 64–68 (type species Gobiosoma parri Ginsburg 1933 , by monotypy).

Enypnias Jordan and Evermann, 1898: 2231, 2233–2234 (type species Gobius seminudus , by original designation; proposed as a subgenus of Garmannia )

Diagnosis

A genus of Gobiosomatini distinguished by the following combination of characters, not listed in order of taxonomic importance: first dorsal fin with VII spines; pelvic fins completely united by a membrane along their entire length, forming cup-like disc with well-developed, smooth anterior frenum; 27 vertebrae (11 precaudal +16 caudal); dorsal pterygiophore formula 3–221110; hypurals 1–2 fused with hypurals 3–4 and the terminal caudal vertebral element; one epural; head, nape, abdomen and prepelvic region without scales; head pores D and E always present; supraoccipital with expanded lateral wings; maxilla with no dorsal process on its posterior edge; outer edges of lower jaw without barbels.

Description

Fins. First dorsal fin VII; second dorsal fin I,9–14; anal fin I,8–11; pectoral fin rays 15–22; pelvic rays I,5; pelvic fin rays united by membrane along their entire length, forming a cup-like disc with well-developed anterior frenum and a smooth margin; caudal fin rounded to truncate; segmented caudal fin rays 17; branched caudal fin rays 13–16.

Scales. Head, nape, abdomen, pre-pelvic area, and pectoral fin base without scales; squamation on truck of body highly variable, ranging from being completely naked, to being heavily scaled posteriorly with scales extending anteriorly to axis of pectoral fin; scales on sides of body ctenoid or cycloid; modified basicaudal scales present in several species.

Vertebral and caudal skeleton. Vertebrae 27 (11 precaudal + 16 caudal); pterygiophore formula of first dorsal fin 3–221110; first two anal pterygiophores inserted anterior to haemal arch; hypurals 1–2 fused with hypurals 3–4 and terminal vertebral element; one epural; first 5–10 vertebrae with pronounced anterior zygapophyses; ventral post-cleithra absent.

Head. Cephalic lateralis pores B', C(s), D(s), E, F, H' typically present; supraopercular pores K', L' present in some species; two to three preopercular pores present (M', O' or M', N, O'); sensory papillae arranged in transverse pattern with four to six suborbital transverse rows; row b usually beginning anteriorly beneath posterior margin of eye; papillae row n in two distinct segments, not continuous across nape; posterior nare on short tube; anterior nare on tube slightly longer and stouter than posterior nare; barbel adjacent to anterior nare present in some species; barbel near anterior margin of eye present in one species ( G.seminudum ); barbels on snout present in several species, often as a small wart-like projection; mental frenum developed into a pair of barbels in several species; no barbels along outer edge of lower jaw; gill opening as a small slit restricted to just anterior of the pectoral fin base; rostral frenum absent.

Cranial osteology. Supraoccipital with prominent lateral wings; lateral wings of supraoccipital articulating with sphenotic in most species; metapterygoid broad, extending over quadrate; maxilla without prominent dorsal process.

Teeth. Teeth in both jaws arranged in two or three rows anteriorly, one or two rows posteriorly; outer rows of teeth in both jaws typically as enlarged canines; teeth in outer row of upper jaw typically larger in males than in females.

Urogenital papillae. Male papillae triangular, conical, or bilobed (only in G.hildebrandi ); male papillae sometimes heavily pigmented; female papillae stout, bulbous, and widely open at its tip, with the edges of the opening being bilobed or crenulate.

Sexual dimorphism. Adult males often with slightly longer jaws and larger outer rows of teeth than adult females; some species with elongate filamentous dorsal spines in males; some species with strong sexual dichromatism, with males being dark and drab and females being barred or mottled.

Comparisons

Gobiosoma can be distinguished from all non-Gobiosomatini gobies by its low vertebral count (11 precaudal + 16 caudal), the presence of seven spines in the first dorsal fin, a dorsal pterygiophore insertion pattern of 3–221110, having the first two anal pterygiophores inserted anterior to the haemal arch, and in having an unossified scapula. Gobiosoma (and other Gobiosoma group species) differ from the Microgobius group genera ( Akko , Antilligobius , Bollmannia , Microgobius , Palatogobius , Parrella ) in having hypurals 1–2 fused with hypurals 3–4 and the terminal vertebral element, having papillae row n comprised of two sections that do not unite across the dorsum, a round or truncate caudal fin, and a metapterygoid process that does not overlap the quadrate.

Among fellow Gobiosoma group genera, Gobiosoma can be distinguished from Chriolepis , Eleotrica , Gobulus , Gymneleotris , Psilotris , Pycnomma , Robinsichthys and Varicus , in having completely united pelvic fins, which form a cup-like disc with a well-developed frenum, versus having incompletely united or completely separate pelvic fins. Gobiosoma is easily distinguished from the eastern Pacific Ophiogobius and the western Atlantic Pariah in having seven dorsal spines (versus eight), having 27 vertebrae (versus 32 in Ophiogobius , 29 in Pariah ). Ophiogobius also has a bilobed tongue, whereas the tongue is truncate in Gobiosoma . Vertebral counts, and in come cases, first dorsal fin elements also distinguish Gobiosoma from species of Evermannichthys , which possess three to seven dorsal spines and 29–36 vertebrae. Gobiosoma differs from Aboma in having fused hypurals (hypurals 1–2 not fused to hypurals 3–4 and terminal vertebral element in Aboma ), and in lacking head pore G (pore G present in Aboma ).

Gobiosoma is distinguished from the genera Elacatinus and Tigrigobius by having 27 vertebrae (11 + 16) versus 28 (11 + 17). Unlike Gobiosoma , all species we have examined of Elacatinus , and most species of Tigrigobius , also have a reduced supraoccipital that does not possess prominent lateral wings (supraoccipitals often round or oval instead; exceptions being T.macrodon and T.zebrella ). Similarly, Ginsburgellus and Risor also differ from Gobiosoma in having 28 vertebrae and a reduced supraoccipital.

Gobiosoma differs from the genera Aruma , Nes and Barbulifer primarily in configuration of the head pores. Nes lacks all head pores. Aruma lacks pores C and E ( Hoese 1976), and Barbulifer lacks pores C, D and E. Pores D and E are present in all species of Gobiosoma , and pore C is present in nearly all species (sometimes missing in G.seminudum and G.homochroma ). The number and distribution of barbels is also more extensive in Barbulifer than Gobiosoma . Gobiosoma species never have prominent barbels on the edges of the lower jaw or behind the jaw whereas these regions have barbels in at least one species of Barbulifer .