Gobiosoma hemigymnum ( Eigenmann & Eigenmann 1888 )

Van Tassell, James L., Joyeux, Jean-Christophe, Macieira, Raphael Mariano & Tornabene, Luke, 2015, Status of Gobiosoma (Teleostei: Gobiidae) from Brazil: description of a new species, redescription of G. hemigymnum, molecular phylogeny of the genus, and key to Atlantic species, Zootaxa 4007 (4), pp. 451-480 : 456-461

Gobiosoma hemigymnum ( Eigenmann & Eigenmann 1888)

Common name: Half naked goby

Nome comum (Portuguese): Amboré zebra Figs. 1–3

Gobius hemigymnus Eigenmann & Eigenmann, 1888: 66 –67 (type locality: West Indies, exact location unknown). See discussion for additional information.

Garmannia hemigymna (Eigenmann & Eigenmann) . Ginsburg, 1933: 57 –58 (placed in subgenus Risor ); Fowler, 1940: 791 (listed from Rio de Janeiro); Fowler, 1941: 177 (in checklist of fishes from Rio de Janeiro); Fowler, 1951: 30 –31 (redescribed based on two specimens); Robins, 1960: 284 (removed from genus Risor , Garmannia synonymized with Austrogobius ).

Garmannia mediocricula . Ginsburg, 1942: 365 –366 (described based on same material as Fowler’s references above); Robins, 1960: 284 (cited); Robins, 1964: 402 (compared to G. grosvenori ).

Gobiosoma hemigymnum (Eigenmann & Eigenmann) . Böhlke & Robins, 1968: 51 –52, 59–60, 155 ( key to genera, placed in subgenus Austrogobius , key to species, species account, comments on holotype, re-examination of holotype, synonymy with G. mediocricula , meristics); Lucena & Lucena, 1982: 43, 45 (coloration, B&W photograph); Menezes & Figueiredo, 1985: 60 –61, 68–69, 105 ( key to genera and species, species account, meristics, ink drawing of largest specimen [J.L. Figueiredo, pers. comm.]); Carvalho-Filho, 1999: 209 –210 (species account, re-drawn from Menezes & Figueiredo, 1985 [A. Carvalho-Filho, pers. comm.]); Murdy & Hoese, 2002: 1782 –1790, 1794 ( key to species, listed); Moura et al., 2003: 99 (listed); Freire & Carvalho-Filho, 2009: 118 (listed, Portuguese common name); Van Tassell, 2011:154 (listed).

Gobiosoma hemigymnum ( Jordan & Evermann, 1888). Moura et al., 2005: 120 (error in authors’ names, listed).

Gobiosoma parri . Ginsburg, 1933: 44 –46 (type locality: Pocitos, Uruguay, description based on juveniles); Dawson, 1963: 585 (in subgenus Dilepidion , name only); Böhlke & Robins, 1968: 58, 155 (in subgenus Austrogobius , description, meristics, table); Cervigón & Bastida, 1974: 14 –20 (drawing body and basicaudal scales, measurements for 11 specimens of 15 to 41 mm TL, comments on scale development); Menni et al., 1984: 187, 322 (in subgenus Austrogobius , listed, drawing from Cervigón & Bastida, 1974); Weiss et al., 1984: not paginated (larvae at the entrance of Patos Lagoon, state of Rio Grande do Sul); Menezes & Figueiredo, 1985: 69 (cited; authors note that "as described by Cervigón & Bastida (1974), [ G. parri ] should not be different from [ G. hemigymnum ]". Muelbert & Weiss, 1991: 48 –50, 52–53 (larvae at the entrance of Patos Lagoon); Acha, 1994: 337 –343 (larval development); Irigoyen & Galván, 2009: 38 (habitat, behaviour, color picture); Van Tassell, 2011:154 (listed).

Austrogobius parri . de Buen, 1950: 122 (synonymy, description of genus); 1951: 63–68 (made type for new genus, redescription, illustrated).

Garmannia parri . Robins, 1960: 284 ( Austrogobius synonymized with Garmannia ); Robins & Böhlke, 1964: 5 (retained in Garmannia ).

Material examined: SANTA CATARINA, BRAZIL: MZUSP 46631, 1, MZUSP 46666, 1, A. Carvalho-Filho, January 1988, Porto Belo; MZUSP 55330, 4, R.L. Moura, A. Carvalho-Filho, C.H. Flesch & R. Francini-Filho, 15 December 1998, Ilha do Arvoredo, Florianópolis, 27° S 48° W, depth 3–9 m; MZUSP 55368, 1, R.L. Moura, A. Carvalho-Filho, C.H. Flesch & R. Francini-Filho, 16 December 1998, Ilha do Arvoredo, Florianópolis, 27°17'30" S 48°22'00" W, depth 8 m; MZUSP 55404, 1, R.L. Moura, A. Carvalho-Filho, C.H. Flesch & R. Francini-Filho, 17 December 1998, Ilha do Arvoredo, Florianópolis, depth 11 m; CIUFES 2596, 1, CIUFES 2600, 4, AMNH 262810, 25, J.-C. Joyeux, 23 May 2013, Lagoa da Conceição, Florianópolis; UF 187660, 11, CIUFES 2599, 9, J.-C. Joyeux, 21 May 2013, Lagoa da Conceição, Florianópolis; CIUFES 2628, 26, J.-C. Joyeux, 22 May 2013, Lagoa da Conceição, Florianópolis.

RIO GRANDE DO SUL, BRAZIL: MZUSP 65312, 3 (of 4), G.Q. Benvegnú, 18 August 1972, N.Oc. "Prof. W. Besnard", estação 1894, 32 º58´S 52º30´W, depth 13m; MZUSP 65328, 2, G. Phonier, 0 1 August 1974, Barra de Tramandaí, Tramandaí.

URUGUAY: USNM 86677, 5 of 7, paratypes of Gobiosoma parri, Hugh M. Smith , 0 8 November 1922, tidepool, Pocitos; ANSP 80831, 3 of 4, Luis P. Barattini, February 1932, Puerto de Montevideo, radiograph; ANSP 121399, 1 Luis P. Barattini, February 1932, Puerto de Montevideo, c&s; CIUFES 2668, 1, A. Carvalho-Filho, 20 April 2013, Rio de la Plata estuary, tidepool at Malvin Beach, Montevideo; CIUFES 2669, 1, A. Carvalho-Filho; 22 April 2013, tidepool at Brava Beach, Punta del Este.

Diagnosis. A species of Gobiosoma distinguished from other members of the genus by the following characters: body scaled from caudal peduncle to base of pectoral fin, scales in a wedge shape to under posterior of first dorsal-fin base, wedge ending abruptly, then continuing forward in a narrow, straight row of 1–2 scales high along midline; a naked area extending from mid- pectoral-fin base to (or past) posterior of second dorsal-fin base and from mid-pectoral-fin base to (or past) posterior end anal fin ray base; upper jaw 34.6 % in head length; lateral scales modally 31; pectoral fin 19 (17–21); maximum size to 44 mm SL.

General morphology. Meristic and morphometrics given in Table 3 . Body cylindrical, elongate; head rounded in profile; eyes dorsolateral (mean followed by range in parentheses) 26.6% (21.8–34.8) in HL; maxilla generally extending posteriorly to a vertical under rear of pupil; upper jaw length 34.6% (28.3–53.5) in HL; anterior and posterior nares are tubes without flaps or tentacles; posterior naris 1/3 height of anterior naris (lower in juveniles); very small wart-like barbel in front of eye, near anterior naris; males with a triangular, wide, flattened urogenital papilla; female papilla, slightly tapering, not flattened, with large opening at end; juveniles with urogenital papilla similar to that of males but shorter, less flattened and rounder at tip.

Fins: Counts for holotype followed by (range; mode). First dorsal VII (VII; VII), no elongate or filamentous spines; first dorsal connected to second dorsal by a low membrane; second dorsal fin falling short, or just reaching caudal fin when adpressed; second dorsal I,11 (I, 10–I,11; I,11); anal I,9 (I, 8–I,9; I,9), not reaching caudal when adpressed; pectoral counts for left fin followed by right, 17/18 (17–21/18–21; 19/19), fin ovate, reaching anterior of anal fin when adpressed; caudal segmented rays 17 (16–17; 17), branched rays, holotype unknown (13–15; 14); pelvic fin I,5 (I,5; I,5) rounded to ovate, not reaching anus when adpressed.

Scales: ( Fig. 4 A) Counts for holotype followed by (range; mode). Lateral scales rows 31 (3–35; 31), Böhlke and Robins 1968 counted “about 36” scales in the holotype, however we count 31; head, nape, abdomen, prepelvic region and belly without scales; scales ctenoid, with pigmented posterior edge; body scaled generally from caudal peduncle to base of pectoral fin, in a wedge shape, to under posterior of first dorsal-fin base, then continuing anteriorly in a narrow, straight row of 1–2 scales along midline; a naked area extending diagonally from midpectoral-fin base to (or past) posterior of second-dorsal fin base (generally terminating posterior to fin base) and from mid-pectoral-fin base to (or past) base of posteriormost anal-fin ray (generally terminating posterior to fin base); four basicaudal scales extending on to caudal fin base, the dorsal and ventral-most with elongate ctenii ( Fig. 4 E); lateral scale pattern exhibiting some variation (see comparison section below).

Teeth: Upper jaw with 3–4 rows anteriorly tapering to a single row extending to near terminus of maxilla; outer row with larger teeth; all teeth in upper jaw conical, pointed with recurved tip; lower jaw with 3–4 rows anteriorly, tapering to a single row near terminus of dentary; outer and inner row of lower jaw with larger teeth, inner row consisting of only a few large teeth, well-spaced along the anterior third of the jaw, teeth in inner row larger in males then females.

Lateral-line system ( Fig. 3): Cephalic lateral line system with pores B', C(s), D(s), E, F, H' and posterior oculoscapular pores K', L'; preopercle canal with pores M', N and O'; supraorbital canals fused between the eyes with only single canal present.

Sensory papillae with transverse pattern; row 1 extending from orbit to row d; rows 2 and 3, extending almost to orbit; row 5 s from orbit to anterior of b; row 6 not reaching row b; row 7 represented by 2 papillae; row b short; row d continuous; row 5 i under b and extending below the level of d by 3–4 papillae; dorsal row g with 3–4 papillae; row o with 2 papillae; row m not observed; row n extending from level of pore F, medially to just posterior to pore E.

Color in recently preserved specimens ( Fig. 2 ). Background color of head and body a pale brown; ventral surface from throat to anus, including chest and pelvic fin, uniformly pigmented, paler than sides of body. Body with series of eight dusky bars; first starting under anterior of first dorsal (D1); second starting under D1 spine 5; third just anterior to insertion of second dorsal (D2); fourth through 6th bar located under D2; seventh bar in middle of caudal peduncle; the eighth dusky bar, a thin, distinct vertical dusky line on the base of caudal fin rays; dusky bars not extending onto belly; barred pattern poorly developed in some individuals, when poorly developed, pattern more evident on dorsal part of body; dusky bars with slightly duskier outer edges; edges vertical, straight, never wavy. A series of dusky spots present on lateral midline in the center of each dusky bar, sometimes double; the last spot on caudal peduncle frequently a anteriorly directed triangle. Head with three dusky spots located between the posterior of the eye and the upper pectoral fin base; first directly behind eye, second above preopercle, third above posterior edge of opercle; head pattern frequently with dusky bar extending forward and down from the anteroventral edge of eye to the mediolateral upper lip, often extending onto lip and chin; second bar on head from below the middle of the eye ventrally to below posterior corner of mouth; a thin line of pigment along most of the posterior of the preopercle, near but not at the edge; edge of posterior preopercle dusky; anterior edge of the opercle dusky. Dorsal fins with body bars slightly extending onto base of fin membranes, remainder of fins dusky with melanophores more concentrated in membranes than on elements, occasionally in a weak banding pattern. Anal fin dusky with melanophores concentrated on membrane between elements. Pectoral fin with two spots located on base of fin rays, on the upper and lower third of the fin, remainder of fin dusky. Pelvic fin dusky with melanophores concentrated along membrane between rays. Caudal fin transparent with several vertical lines of melanophores. No apparent sexual dichromatism.

Osteology: Osteology based on one cleared and stained specimen ( ANSP 121399), radiographs of types and ANSP 80831. Vertebrae 11 precaudal and 16 caudal (total 27); dorsal pterygiophore formula 3- 221110; anal pterygiophores anterior to first haemal spine 2; hypurals 1/2 fused to hypurals 3/4 about ¼ to ½ the length.

Distribution, habitat and natural history ( Fig. 5 ). Gobiosoma hemigymnum has been documented to occur, based on recent collections, in the southwestern Atlantic from Rio de Janeiro, Brazil, about 23º S, to Mar del Plata, Argentina, about 38º S. It may occur near Cabo Frio, about 22.8º S if the holotype was collected by the Hessler expedition in dredge 21 (See discussion for details). It inhabits estuarine, intertidal and shallow coastal areas; frequently found associated with epilithic organisms (2 centimeters or more in size) found at depths ranging from tidepools to 13 meters. Specimens from Lagoa da Conceição (state of Santa Catarina) were collected by one of us (JCJ) while snorkeling along the granitic shores in 1.5 to 2 meters of water in an area where the non-native Styela plicata (Lesueur 1823) occurs ( Barros et al., 2009). This solitary ascidian forms extensive aggregations in bands about 1 meter below the lower limit of the intertidal zone. Other species collected in the area included: the gobiid Bathygobius soporator (Valenciennes 1837) , the native blenny Hypleurochilus fissicornis (Quoy & Gaimard 1824) and the invasive blenny Omobranchus punctatus (Valenciennes 1836) , and the gobiesocid Gobiesox barbatulus Starks 1913 . In Mar Chiquita lagoon (Buenos Aires Province, Argentina) the species has been recorded in high numbers associated with the reefs built by the invasive tubeworm Ficopomatus enigmaticus (Fauvel 1923; also known as Mercierella enigmatica ) (Cervigón & Bastida, 1971). Nearby in Mar del Plata, the same authors indicate that G. hemigymnum inhabits the encrusting community in both the harbor and the mesolittoral zone of Cabo Corrientes. In the latter community, composed of the mussels Brachidontes rodriguezii (d'Orbigny 1842) and Mytilus edulis platensis d'Orbigny 1842 , G. hemigymnum is rare. In Uruguay, G. hemigymnum was found in tidepools 20 and 50 cm deep with clear water and sandy bottoms (A. Carvalho-Filho, pers. comm., 17 May 2013). Other fish species in the pools included: H. fissicornis , juveniles of Mugil curema Valenciennes 1836 and adults of Jenynsia multidentata (Jenyns 1842) . Both Barbulifer enigmaticus and G. hemigymnum have been collected within the same tidepools in São Paulo (J.L. Figueiredo, pers. comm., 20 September 2010). The species has been documented at 8–13 meters in northern Argentina ( Irigoyen & Galván, 2009) and southern Brazil (MZUSP catalogued specimens 55330, 55368, 55404, 65312). Medeiros (2013) reported that G. hemigymnum uses the empty shells of the cultured mussel Perna perna (Linnaeus 1758) for spawning and is an intermediary host of Bucephalus margaritae (Ozaki & Ishibashi 1934) , a trematode worm parasitic on the mussel, in Santa Catarina.

Figures

FIGURE 1. (A) MCZ 27124, Holotype of Gobiosoma hemigymnum, photographed after fixation, 44.1 mm TL; (B) USNM 119876, Gobiosoma hemigymnum (Holotype of Garmannia mediocricula), photographed after fixation, 28 mm TL; (C) USNM 119899, Gobiosoma hemigymnum (Paratype of Garmannia mediocricula), photographed after fixation, 29 mm TL. Photograph (A) Museum of Comparative Zoology, Harvard University, © President and Fellows of Harvard College; photographs (B), (C) by Sandra Raredon USNM.

FIGURE 2. Gobiosoma hemigymnum, photographed after fixation in formalin 10 % and preservation in ethyl alcohol 70 %. (A) CIUFES 2628 - 1, 34.31 mm TL, adult male; (B) CIUFES 2628 - 2, 33.84 mm TL, adult male; (C) CIUFES 2628 - 3, 20.78 mm TL, male; (D) CIUFES 2628 - A, 28.40 mm TL, adult female; (E) CIUFES 2628 - B, 28.23 mm TL, adult female; (F) CIUFES 2628 - C, 19.95 mm TL, female. Photographs by R. M. Macieira.

FIGURE 4. Scale patterns of A) Gobiosoma hemigymnum, B) G. alfiei, C) G. spilotum, D) G. grosvenori. Shaded areas in A-D indicate distribution of scales on body. E) Distribution of basicaudal scales, including modified basicaudal scales on dorsal and ventral caudal peduncle.

FIGURE 5. Distribution of Gobiosoma alfiei (squares), G. hemigymnum (circles), and G. spilotum (triangle). Closed symbols are sites where samples were sequenced. Open symbols are sites with morphological samples only. The “? ” represents possible locality for holotype of G. hemigymnum.

Tables

TABLE 3. Meristic and morphometric data for Gobiosoma hemigymnum based on re-examination of the holotypes of G. hemigymnum and Garmannia mediocricula, the paratype of G. mediocricula and recently collected material in Uruguay and southern Brazil. Morphometric data expressed as percent of standard length, of head length (†) or of jaw length (‡). n = number of individuals, including types.

Meristic characters First dorsal fin	Holotype G. hemigymnum VII	Holotype G. mediocricula VII	Paratype G. mediocricula VII	n 33	Range VII–VII	Mode VII
Second dorsal fin Anal fin Pectoral fin right	I,11 I,9 18	I,11 I,9 19	I,11 I,9	36 36 34	I,10–I,11 I,8–I,9 18–21	I,11 I,9 19
Pectoral fin left Pelvic fin Segmented rays in caudal fin	17 I,5 17	19 I,5 17	19 I,5 17	32 40 35	17–21 I,5–I,5 16–17	19 I,5 17
Branched rays in caudal fin Scales in longitudinal series Morphometric characters Total length (mm)	31 Holotype G. hemigymnum 44.1	30 Holotype G. mediocricula 26.0	32 Paratype G. mediocricula	28 35 n 36	13–15 3–35 Range 17.3–44.1	14 31 Mean ± SD 26 ± 6.6
Standard length (mm) Standard length (% SL) Head length	36.0 81.8 26.3	21.5 82.7 32.4	23.4 32	38 36 38	14.0–36.0 78.5–83.8 26.3–32.4	21.1 ± 5.4 81.1 ± 1.2 29.8 ± 1.6
Head depth Head width Postorbital length	18.8 21.6 12.1	18.5 21.9 17.6	16.6 19.6 9.3	38 38 37	15.5–21.5 13.9–25.4 9.3–19.3	18.3 ± 1.6 21.7 ± 2.3 16.8 ± 1.8
Upper jaw length Interorbital width Eye diameter	14 3.1 6.3	12.9 2 8.9	13.7 2 7.5	38 38 37	8.3–14.0 1.2–5.3 6.0–10.0	10.3 ± 1.4 2.5 ± 0.9 7.9 ± 1.1
Pupil diameter Anterodorsal length First dorsal spine length	2.4			35 35 23	2.1–6.0 4.8–10.7 10.0–17.2	3.6 ± 0.9 7.4 ± 1.4 12.9 ± 2
Depth of body at D1 origin Pectoral-fin length - left Pectoral-fin length - right	18.9	19.9	19.8	37 30 31	12.7–21.4 20.6–27.9 20.8–28.4	18 ± 1.9 24.5 ± 1.6 24.4 ± 2.1
Pelvic-fin length Caudal peduncle depth Caudal fin length	15.7	15.1	14.7	33 38 34	17.2–24.8 9.1–15.7 19.2–28.3	20.5 ± 1.6 12.6 ± 1.4 23 ± 1.7
Postorbital length † Upper jaw length † Interorbital width †	46.2 53.5 11.6	54.2 39.7 6.2	29.1 42.9 6.4	37 38 38	29.1–68.8 28.3–53.5 4.0–17.8	56.4 ± 6.4 34.6 ± 5 8.4 ± 3.2
Eye diameter † Pupil diameter † Eye diameter ‡	24.1 9 45.1	27.3 68.8	23.4 54.5	37 35 37	21.8–34.8 6.9–20.0 45.1–114.3	26.6 ± 3.5 12.1 ± 3 78.7 ± 17.1