Varicus prometheus, Fuentes & Baldwin & Robertson & Lardizábal & Tornabene, 2023

Fuentes, Katlyn M., Baldwin, Carole C., Robertson, D. Ross, Lardizabal, Claudia C. & Tornabene, Luke, 2023, Two new species of Varicus from Caribbean deep reefs, with comments on the related genus Pinnichthys (Teleostei, Gobiidae, Gobiosomatini, Nes subgroup), ZooKeys 1180, pp. 159-180 : 159

Varicus prometheus sp. nov.

Figs 2 , 3 , 4 Promethean goby, Gobio prometeico (Spanish)

Type locality.

Roatan, Honduras; western Caribbean.

Holotype.

Honduras • 1 female 30.5 mm SL; western Caribbean, island of Roatan, west End, off Half Moon Bay, sta. IDABEL18-02; 16.304°N, 86.598°W; 247 m depth; 5 June 2018; Luke Tornabene, D. Ross Robertson and Karl Stanley; 5% quinaldine-sulfate dispersed from Idabel submersible; UW 158119, DNA sample ROA18032.

Generic placement.

In addition to molecular characters supporting the phylogenetic placement of this species, the following morphological characters support its inclusion in the genus Varicus (sensu Tornabene et al. 2016b): dorsal-fin pterygiophore formula of 3-221110; 27 vertebrae (11 precaudal + 16 caudal, but see “Remarks” section below); one anal-fin pterygiophore inserted anterior to first haemal spine (but see ‘Remarks’ section below); anal-fin rays I,8; head pores absent; pelvic fins completely separate, lacking both anterior frenum and membrane connecting bases of innermost pelvic-fin rays; fifth pelvic-fin ray unbranched.

Diagnosis.

Varicus prometheus is distinguishable from all other Varicus species by the following combination of characters: second dorsal fin I,9; anal fin I,8; pectoral fin 17; scales absent except for two modified basicaudal scales; pelvic rays 1-4 unbranched without fleshy tips; one anal-fin pterygiophore inserted anterior to first haemal spine (but see ‘Remarks’ section below); body with four incomplete brown saddles on pale to bright yellow background; pelvic and pectoral fins white to pale yellow in life, dorsal, anal, and caudal fins pale to bright yellow.

Description.

General shape: body robust, widest and deepest at posterior of head, trunk tapering in width and depth posteriorly, dorsal profile of head gently sloping from dorsum to tip of snout.

Morphometrics (%SL): head length 26.9; eye diameter 7.5; snout length 7.5; upper-jaw length 12.8; post-orbital length 13.1; predorsal length 36.7; body depth at 1st dorsal-fin origin 18.7; body depth at anal-fin origin 17.0; preanal length 61.0; body depth at caudal peduncle 10.5; caudal-peduncle length 12.1; pectoral-fin length 32.8; pelvic-fin length 25.6.

Median and paired fins: first dorsal fin VII; second dorsal fin I,9; anal fin I,8; pectoral fin 17; pelvic fins I,5, fins well separated, lacking both anterior frenum and membrane connecting bases of innermost rays; 4th pelvic-fin ray longest, extending posteriorly to base of anal-fin spine; rays 1-4 all unbranched, no fleshy tips; 5th ray unbranched and <10% the length of the 4th ray; caudal fin shape undeterminable due to poor condition of specimen, branched caudal-fin rays 13, segmented caudal-fin rays 17.

Vertebral skeleton (Fig. 3 ): 27 vertebrae, 11 precaudal vertebrae, 16 caudal vertebrae (see ‘Remarks’ section below); dorsal-fin pterygiophore insertion pattern of 3-221110.

Head: jaw terminal, angled approximately 45 degrees from horizontal axis of the body, extending posteriorly to vertical through anterior margin of pupil; anterior nares on a short tube, posterior nares small, barely visible as an opening on a slightly raised rim immediately anterior to eye; eyes large, dorsolateral, extending to dorsal profile of head; operculum opening slightly wider than width of pectoral-fin base; teeth difficult to accurately assess due to condition of specimen, teeth in both upper and lower jaws in multiple rows, two to three rows anteriorly, with outer row in upper jaw slightly enlarged with recurved canines.

Sensory papillae (Fig. 4 ): sensory papillae on the sides of head of holotype are badly damaged, and the following description is a composite of both sides of the head. Five transverse rows extending from below eye, with two longitudinal rows; first longitudinal row (row ‘d’ of Sanzo 1911) at level just above angle of jaw row, extending between second and fourth transverse row; second longitudinal row (row ‘b’ of Sanzo 1911) short, originating below posterior margin of eye immediately posterior to fourth transverse row; first transverse row originating at anteroventral corner of eye, second transverse row below originating at anterior margin of pupil, third transverse row originating below posterior margin of pupil, fourth transverse row (row 5i/5s of Tornabene et al. 2016b) originating below posterior margin of eye and extending below longitudinal as a single continuous row (5i/5s continuous versus separate), fifth transverse row diagonal, originating at posterior margin of eye, well above fourth row; several short vertical rows of papillae above operculum; a vertical row of four evenly space papillae near anterior margin of operculum; a short oblique row of papillae across middle of operculum; papillae row p not apparent except for a single papilla peʹ behind each eye; body with approximately 15 short vertical rows of papillae evenly spaced along lateral midline, beginning below origin of second dorsal fin and continuing onto caudal peduncle.

Squamation: scales on head and body absent except for two modified basicaudal scales with enlarged ctenii present at dorsal and ventral margins of caudal-fin base.

Genitalia: female with short, slightly rounded, conical papilla, wider at base and tapering to a slight point; male unknown.

Color before preservation (Fig. 2 ): background color of head and body white to pale yellow, with upper portion of head and body slightly brighter yellow than posterior half of body (pigmentation of which is more visible when fish was photographed against white vs. black background). Head with areas of bright yellow pigment lightly speckled with small brown melanophores across upper jaw and snout; four dark bars formed by speckled brown melanophores; first two bars, slightly narrower than pupil diameter, extending ventrally from interorbital, one across the anterior eye and ending at posterior tip of jaw and the second crossing slightly posterior to pupil and ending mid-cheek; third bar originating well behind eye at dorsal midline and extending ventrally slightly onto middle of opercle; and fourth bar wider than first three, anterior to first dorsal fin, extending ventrally to approximately to just above pectoral-fin base. Eyes with green-yellow irises speckled with silvery dots and a thin silvery ring around the pupil. Body pale yellow to white with four dark saddles heavily speckled with brown melanophores; first saddle slightly narrower in width than eye diameter, located at middle of base of first dorsal fin extending ventrally to lateral midline where melanophores become less dense; second saddle about equal in width to eye diameter, located at anterior of second dorsal fin extending ventrally just short of lateral midline; third saddle slightly wider than eye diameter, located under rear of second dorsal fin base, extending ventrally to just beyond lateral midline; fourth saddle located laterally on the caudal peduncle at base of caudal fin, the front border rounded and the rear border straight, slightly larger than eye diameter. First dorsal fin bright yellow with a few brown melanophores along base immediately above saddle on body, few scattered melanophores on interradial membranes; second dorsal fin similarly colored as first. Caudal fin with a very wide oblique yellow bar down middle of fin rays. Anal fin bright yellow. Pectoral-fin base yellow with blotch of brown melanophores at center on the upper third of the fin base, extending to origin of rays. Pelvic fins pale.

Color in preservation (Fig. 2 ): body and head uniformly pale yellow, fins translucent. Only remaining pigment consisting of light speckling of small melanophores on trunk at location where dark saddles occurred in life.

Habitat.

The holotype was collected at from the deep-reef slope at 247 m on sand with Halimeda rubble.

Distribution.

Known only from the type locality off Roatan, Honduras.

Etymology.

The specific epithet Varicus prometheus is a patronym in reference to the Greek god Prometheus. In Greek mythology, as punishment from the god Zeus, Prometheus had his liver eaten out by an eagle, only to have the liver grow back overnight so it might be eaten again the next day. The name refers to the fact that the abdomen of the holotype of the new species was partially eaten by a hermit crab. The name is treated as a noun in apposition.

Remarks.

Varicus prometheus most likely possesses 27 total vertebrae, like all other species in genus. However, our radiographs did not have enough resolution for us to determine whether the 12th vertebra had a haemal spine (if present, it is very reduced) rendering it the first caudal vertebra versus the last precaudal vertebra (Fig. 3 ). Thus, the counts of precaudal and caudal vertebrae may be 11+17 or 12+16. Accordingly, it is unclear how many anal-fin pterygiophores are inserted anterior to the first haemal spine. All other species of Varicus have one anal-fin pterygiophore inserted anterior to the haemal arch that is present on the 12th vertebra (other species of Gobiosomatini have two pterygiophores inserted here, including the morphologically similar genus Psilotris Ginsburg, 1953). In some rare instances in Varicus , the haemal arch on the 12th vertebra is very reduced and does not insert deeply into the space between the first two anal-fin pterygiophores, making it incorrectly appear on the x-ray as if there are two anal pterygiophores inserted before the “first” haemal spine on the 13th vertebrae, rather than one pterygiophore inserted before the 12th vertebra (Fig. 3 ; also see Tornabene et al. 2016b, fig. 2). This is likely the case with V. prometheus , and we tentatively consider the vertebral counts to be 11+16 with a single anal-fin pterygiophore inserted before the haemal arch.

Varicus prometheus is easily distinguished from other species of Varicus and species in the morphologically similar genus Psilotris (Table 1 ) by the presence of four broad brown saddles on a uniformly yellow body. No other species of Varicus or Psilotris has such saddles, although a few species [e.g., V. adamsi Gilmore, Van Tassell & Tornabene, 2016; V. vespa (Hastings & Bortone, 1981); V. marilynae Gilmore, 1979] have complete or nearly complete vertical bars that are narrower than the saddles in V. prometheus , and V. nigritus has large dark blotches on the body that are as wide as the saddles in V. prometheus but are round rather than saddle shaped (Fig. 5 ). Varicus prometheus lacks scales on the trunk, whereas all other Varicus species except V. lacerta Tornabene, Robertson & Baldwin, 2016, and V. decorum Van Tassell, Baldwin & Tornabene, 2016, have many rows of scales on the trunk. Both V. decorum and V. prometheus possess modified basicaudal scales, which are lacking in V. lacerta . The unbranched pelvic rays of V. prometheus and the presence of one anal-fin pterygiophore (versus 2) inserted before the haemal arch distinguish it from all species of Psilotris .

Figures

Figure 2. Varicus prometheus sp. nov. holotype, UW 158119, 30.5 mm SL, female, prior to preservation (top two photos) and preserved (bottom). Photos by Luke Tornabene.

Figure 3. Vertebral skeleton and anal-fin pterygiophores of Varicus prometheus sp. nov. Yellow numbers are the number of vertebrae.

Figure 4. Sensory papillae pattern for Varicus prometheus. Labels for papillae rows follow Sanzo (1911) as modified by Tornabene et al. (2016 b). Photo by L. Tornabene.

Figure 5. Live or fresh coloration of Varicus species (coloration unknown for V. benthonis and V. bucca) A V. adamsi, photo by L. Tornabene B V. cephalocellatus, photo by B. Brown C V. decorum, photo by B. Brown D V. lacerta, photo by C. Baldwin E V. marilynae, illustration by R. G. Gilmore F V. veliguttatus, photo by C. Baldwin G V. nigritus, illustration by R. G. Gilmor H V. vespa, photo by the crew of the R / V BELLOWS.