Gnatholepis caudimaculata, Larson & Buckle, 2012

Larson, Helen K. & Buckle, Duncan J., 2012, A revision of the goby genus Gnatholepis Bleeker (Teleostei, Gobiidae, Gobionellinae), with description of a new species, Zootaxa 3529 (1), pp. 1-69 : 23-27

Gnatholepis caudimaculata new species

( Figs 9–11 , 12A ; Tables 5–8, 10)

Gnatholepis anjerensis — Randall 1995: 336 ( Oman); Debelius 1998: 180 (Na’ama Bay, Sinai).

Diagnosis. A moderate-sized Gnatholepis (up to 42.5 mm SL) with cycloid scales on head and pectoral fin base, predorsal midline usually naked, distinct flap present at end of lower lip; when alive, body whitish with finely speckled dorsum, characteristic vertical oval blackish to dark grey blotch across caudal fin base, two broad ladderlike orange to reddish stripes along body and oblique black curved or comma-shaped mark on top of eye; second dorsal and anal fin rays nearly always I,11; pectoral rays 15–17, modally 16; lateral scales 25–28, modally 26; 7–10 predorsal scales (usually 8).

Material examined. HOLOTYPE — USNM 327425 , 45 mm SL male, reef near road at Marsa Muqabila , north-west coast Israel, Gulf of Aqaba, V. G. Springer and party, 17 July 1969 . PARATYPES — BPBM 27442 , 4 (18.5–28), Towartit Reef , Sudan, Red Sea, J.E. Randall, 13 January 1980 ; PMR VP.2219, 2(26.5–30.5), Sanganeb , Sudan, Red Sea, S. Bogorodsky, 11 October 2009 ; PMR VP.2220, 1(28.5), Shaab Suadi , Sudan, Red Sea, S. Bogorodsky, 12 October 2009 ; USNM 313779 , 1 (28.5), bay on NW end of Giftun Al Kebir Island, Hurghada, Strait of Jubal , Egypt, H.A. Fehlmann and party, 3 January 1965 ; BPBM 13401 , 1 (34.5), Dahab, Gulf of Aqaba , Egypt, J.E. Randall, 14 June 1972 ; USNM 313780 , 21 (19.5–29), S shore Difnein Island , Ethiopia , V.G. Springer and party, 15 August 1969 ; USNM 399290 , 11 (16–36), reef near road at Marsa Muqabila, north–west coast Israel, Gulf of Aqaba , V.G. Springer and party, 17 July 1969 ; BPBM 18231 , 11 (26–37.5), 1 km N of Coral Island, Gulf of Aqaba , J.E. Randall and O. Gon, 23 September 1974 ; ex-USNM 327464, 3(27–31.5), Zubair Island , Yemen, E. Clark, 30 September 1967 ; BPBM 33350 , 2 (30–36.5), SE side Jana Island , Saudi Arabia, Persian Gulf, J.E. Randall and party, 13 September 1985 ; BPBM 33373 , 1 (42.5), S side Jana Island , Saudi Arabia, Persian Gulf, J.E. Randall and party, 13 September 1985 ; BPBM 33374 , 2 (31–36.5), Jana Island , Saudi Arabia, Persian Gulf, J.E. Randall and party, 13 September 1985 ; BPBM 30457 , 3 (33.5–35), N side Jana Island , Saudi Arabia, Persian Gulf, J.E. Randall and party, 15 June 1984 .

Non-type specimens examined. BPBM 13423 , 2 , El Hamira, Gulf of Aqaba , Egypt ; BPBM 18358 , 1 , Ras Mohammed, S end of Sinai Peninsula, Egypt .

Description. Based on 37 specimens, 26–42.5 mm SL. An asterisk indicates the counts of the holotype ( Fig. 9 ).

First dorsal VI *; second dorsal I,10–I,11* (mean I,10.9); anal I,10–12 (mean I,10.9, I, 11 in holotype), pectoral rays 15*–17 (mean 15.8), segmented caudal rays always 17*; caudal ray pattern always 9/8*; branched caudal rays 7/6 to 7/7* (usually 7/6); lateral scale count 25–28 (mean 26.3, 26 in holotype); TRB 8–11 (mean 10.0*); predorsal

Body compressed, width at anus 9.0–15.9% (mean 13.1%) of SL. Body rather stocky in appearance, body depth at anus 13.4–24.6% (mean 22.0%) of SL, body depth at first dorsal fin origin 21.0–25.7% (mean 23.3%) of SL. Head compressed, slightly broader ventrally, slightly deeper than wide, HL 24.6–30.7% (mean 28.4%) of SL; head depth at posterior preopercular margin 62.8–82.4% (mean 69.8%) of HL; head width at posterior preopercular margin 55.8–88.4% (mean 67.6%) of HL; head profile bluntly pointed to somewhat rounded; nape profile straight to slightly curved. Mouth nearly terminal, fleshy snout tip may slightly overhang tip of jaws, slightly oblique; jaws reaching to anterior half of eye or just below anterior margin of eye in large specimens; upper jaw length 32.1–39.8% (mean 35.4%) of HL. Upper lip smooth, narrower than lower, lower lip papillose close to teeth, with ridge of small papillae along side of lip ending in twist or fold posteriorly, forming triangular flap, lip interrupted at chin. Eye moderate, dorsolateral, 25.0–32.6% (mean 28.6%) of HL; preorbital width 14.6–21.7% (mean 19.0%) of HL. Snout usually bluntly pointed, 26.3–38.2% (mean 32.1%) of HL; posterior naris rounded, close to mid-level margin of eye; anterior naris in short tube, about level with ventral half to middle of eye. Interorbital narrow, 5.8–12.2% (mean 7.8%) of HL. Caudal peduncle compressed, length 14.4–19.5% (mean 17.0%) of SL; caudal peduncle depth 9.8–11.9% (mean 11.0%) of SL.

First dorsal fin rounded to almost triangular, with no spines greatly elongate; second to fourth spine usually longest; when adpressed, spine tips reaching to first to third element of second dorsal fin in males, fin may fall short in females. Second dorsal spine length 13.4–19.1% (mean 17.1%) of SL; third dorsal spine length 13.4–21.8% (mean 17.8%) of SL; fourth dorsal spine length 13.1–19.7% (mean 17.3%) of SL. Second dorsal fin nearly as tall as first dorsal fin anteriorly, fin pointed posteriorly. Anal fin lower than second dorsal fin, anteriormost rays shorter than posterior rays; fin pointed posteriorly. Second dorsal and anal fin rays, when adpressed, reaching caudal fin in males, usually falling just short of fin ray bases in females. Pectoral fin oval to somewhat pointed, central rays longest, 21.4–28.8% (mean 24.8%) of SL; fin reaching back to just above anal fin spine. Pelvic fins fused, frenum with distinctive finely fimbriate margin, fins round to oval, reaching to anal fin spine, 23.6–30.7% (mean 26.7%) in SL. Caudal fin moderate, rounded posteriorly, 25.2–33.0% (mean 29.8%) of SL.

Gill opening restricted, extending anteriorly to lower edge of pectoral base. One or two slender gill rakers on outer face of first arch, closest to angle of arch, remainder of rakers very short and stubby; clumps of tiny pointed papillae present along inner face of first arch; outer rakers on second gill arch mostly replaced by several series of fine papillae; outer rakers on remaining arches low, broad-based. Inner face of upper limb of first gill arch, and to lesser extent, upper limbs of other arches, covered with low dense fleshy papillae which may form clumps or groups; dorsal portion of arch may have short fleshy protuberances ending in one or several papillae. About onethird of first gill arch bound by membrane to inner face of opercle. Tongue tip bilobed.

Teeth in upper jaw in two to three rows across front and one row at side of jaw, outermost row teeth largest,

curved and pointed, largest teeth at front of jaw on either side of symphysis; innermost row teeth small, sharp and evenly sized. Teeth in lower jaw in two to three rows, arranged similarly to upper jaw but outer row teeth smaller in females; posteriormost one or two outer row teeth enlarged or recurved in males.

Predorsal scales cycloid, of variable extent, from just over opercle to (rarely) close up to behind eyes; nape midline usually naked, with scales present on either side of nape. Opercle covered with scales, cycloid or ctenoid or mix of both. Preopercular scales cycloid; occasionally few scales present anterior to vertical dark cheek-bar below eye. Breast with cycloid scales usually reaching up to below mid-opercle. Pectoral fin base with cycloid scales. Belly scales along midline usually cycloid; few ctenoid scales may be present anterior to anus.

Sensory papillae and head pores as in G. anjerensis .

Coloration of fresh material. Photographs of living fish (as G. anjerensis ) appear in Randall (1995) and Debelius (1998). The following description is mostly based on photographs of living fish by Sergey Bogorodsky and Ole Brett ( Figs 10–11 ).

Living fish colour pattern very similar to preserved pattern (see below). Head and body white to slightly greyish white with two broad ladder-like orange to brownish stripes formed by two rows of small rounded spots along body, mid-lateral stripe usually most pronounced and upper stripe (commencing at upper corner of opercle) less distinct to nearly absent; six diffuse to indistinct small brownish blotches interspersed with white patches evenly spaced along lower stripe; most distinct marking a vertically-oriented black or blackish oval to rectangular blotch on mid-base of caudal fin at hypural crease.

Dorsum lightly speckled with small light to dark brown spots and a few small orange spots; may be up to eight evenly spaced patches of bluish white placed above dorsalmost ladder-like orange stripes (or rows of spots). Snout lightly mottled with pearly pale bluish white with some pale diffuse brown mottling near nares. Opercle crossed by bright orange oblique stripe, ending near upper rear corner, may be some light brown mottling around stripe; cheek sometimes with brown mottling around vertical to slightly oblique dark orange to red-brown or dark brown narrow bar or line running from eye down to lower preopercular edge, or cheek only with vertical bar from eye and a short horizontal brownish mark extending anteriorly from rear edge of preopercle; characteristic very dark brown to black oblique to comma-shaped mark across top of eye. Brown-edged bright orange and brown line from behind eye running atop preopercle, opercle and across pectoral fin base (anteriormost part of line usually brown); forming lower edge of diffuse dark brown broadly-forked blotch above fin base and yellow to pale gold spot present in centre of blotch. Pectoral fin base whitish speckled with brown, and brown-edged bright orange bar crossing just above centre of fin base. Upper lip crossed by dark brown line at level of nares and smaller brown or diffuse brown marks may be present at midline of lip. Lower lip, chin and breast white. Iris silvery to pale golden, with brown line (from cheek-bar) ventral to pupil and red-brown to black line above pupil that curves around eyeball in commashape posteriorly.

First dorsal fin translucent to transparent, crossed by narrow irregular brownish lines or series of small brown spots. Second dorsal fin very similar but with series of elongate to oval darker brown spots toward posterior half. Anal fin translucent whitish with rows of irregular small brown spots; may become more elongate posteriorly. Caudal fin translucent white to transparent, crossed by irregular rows of small brown spots and short streaks and vertically-oriented black or blackish oval to rectangular blotch on mid-base of fin. Pectoral fins transparent, lightly speckled with bright white on basal half and with small diffuse brownish blotch on bases of rays near middle of fin (continuation of horizontal orange bar on fin base). Pelvic fins transparent to translucent whitish.

Coloration of preserved material. Head and body yellowish white to whitish, with two broad ladder-like light brown stripes (about one scale wide) along body, first stripe beginning at upper rear corner of opercle and ending on upper surface of caudal peduncle just before fin base, second stripe beginning behind pectoral fin base and ending on lower half of caudal fin base; stripes with slightly darker upper and lower margins; similar stripe along dorsum from origin of first dorsal fin to middle of second dorsal fin (may be replaced by irregular brown speckling or series of about eight diffuse short faint brownish saddles over dorsum); vertically-oriented brownish oval to rectangular blotch on mid-base of caudal fin (at hypural crease).

stripe crossing opercle, ending near upper rear corner; cheek with brown mottling (which may curve around a few unpigmented spots) and vertical to slightly oblique dark brown narrow line running from eye down to lower preopercular edge; distinctive dark brown to blackish oblique to comma-shaped mark across top of eye, beginning above mid-pupil and ending past rear edge of pupil (nearly to rear edge of eye in some specimens) ( Fig. 12A ). Variably intense brownish line running from behind eye atop preopercle and opercle, across pectoral fin base and forming lower edge of pale to dark brown broadly-forked blotch above fin base (unpigmented area usually present in centre of ‘fork’). Pectoral fin base pale to brown-speckled, with darker brown bar crossing just above centre of fin base. Upper lip crossed by brown line or blotch at level of nares and smaller brown spot may be present at midline of lip. Lower lip, chin and breast whitish or lightly dusted with melanophores.

First dorsal fin translucent whitish, crossed by five to six narrow irregular brownish lines, which may be partly broken-up by series of dark spots posteriorly; fin margin faintly dusky. Second dorsal fin very similar but wavy lines mostly broken up into series of elongate to oval dark spots. Dorsal fins more strongly marked in males. Anal fin transparent to translucent with broad dusky margin. Caudal fin translucent whitish to pale yellowish brown, crossed by about eight irregular rows of small brown spots and short streaks; in many specimens most of these markings ‘blurred’ and diffuse except for on upper and lower parts of fin; males with most pronounced spotting. Pectoral fins transparent to lightly speckled with brownish pigment and brownish blotch on bases of rays near middle of fin (continuation of horizontal brown bar on fin base). Pelvic fins transparent to brownish; frenum pale.

Distribution. Restricted to the Red Sea ( Ethiopia, Israel), Gulf of Aqaba and Persian Gulf ( Saudi Arabia). The species has been reported from Oman and Egypt, although identified as G. anjerensis ( Randall 1995; Debelius 1998).

Ecology. Very little information available; depth range of material examined was 0– 17 m. Photographs of living fish show them over white to blackish sand. This species has been shown to exhibit red fluorescence on the dorsal half of the eye by Michiels et al. (2008: fig. 5; fish identified as G. anjerensis ). They identified 20 species of red-fluorescing gobiids (of the genera Bryaninops , Ctenogobiops , Eviota , Fusigobius , Gnatholepis , Istigobius , Pleurosicya and Trimma ). This has been hypothesised to be part of a “private communication system” as the fluorescence occurs in features that are used for intra-specific signals, especially the eyes. As Gnatholepis species have distinctive and slightly different black markings across the dorsal surface of the eyeball, this red fluorescence and the pattern on the eye may be of considerable significance to the fish.

Comparisons. This species is very like G. cauerensis , and replaces that species in the Red Sea. It is distinguished by possession of a vertical black to dark brown blotch on caudal fin base, the ladder-like rows of small spots forming two stripes along the body and the obliquely placed comma-shaped lines atop each eye. It has a slightly lower number of predorsal scales compared to G. cauerensis : 7–9, modally 8, compared to 7–12, modally 9 (comparing data from 27 G. caudimaculata specimens to 113 G. cauerensis ).

Figures

FIGURE 9. Holotype of Gnatholepis caudimaculata n. sp., USNM 327425, 36 mm SL male, Marsa Muqabila, Israel, Gulf of Aqaba. White object in mouth is paper label; pinkish cast to first dorsal fin due to small pebble holding specimen upright.

FIGURE 10. Gnatholepis caudimaculata n. sp., 9 m depth, north of Marsa Alam, Egypt, Red Sea. Photo by Sergey Bogorodsky.

FIGURE 11. Gnatholepis caudimaculata n. sp., Sharm, Sinai, Egypt. Photo by Ole Brett.

FIGURE 12. A, Sketch of dorsal view of head of Gnatholepis caudimaculata n. sp., showing characteristic oblique mark on