Bryaninops discus, Suzuki, Toshiyuki, Bogorodsky, Sergey V. & Randall, John E., 2012

Suzuki, Toshiyuki, Bogorodsky, Sergey V. & Randall, John E., 2012, Gobiid fishes of the genus Bryaninops from the Red Sea, with description of two new species and two new records, Zootaxa 3170, pp. 1-17 : 2-6

Bryaninops discus , n. sp.

Figures 1–3 ; Table 1

Bryaninops erythrops (non Jordan & Seale, 1906) Randall, 1994: 270, pl. 20.

Holotype: BPBM 35695, male, 19.4 mm SL, Sudan, Suakin Archipelago, Saunder's Reef, 17°10'N, 39°23'E, on sea whip, 16 m, J.E. Randall, 11 May 1993.

Paratypes: USNM 398716, 17.7 mm, same data as holotype; BPBM 35724, 2: 13.6 & 18.7 mm SL, Gulf of Aden, Djibouti, Seven Brothers Islands, Rhounda Komaxtou, reef in 26 m, on Cirrhipathes sp., J.E. Randall, 19 May 1993.

Diagnosis. Dorsal-fin rays I,8; anal-fin rays I,9; pectoral-fin rays 14–15, some rays branched; scales on body reaching forward to or nearly to above base of pectoral fins, the longitudinal scale series 34–52, transverse scale rows 10–13; body very slender, the depth at anus 11–13% SL; head length 28–30% SL; head width slightly greater than head depth; head depth 43.5–50% head length; snout length 29–31% head length; jaws same length or lower jaw slightly protruding; lower jaw rounded in ventral view; gill opening wide, extending forward to below posterior edge of orbit; posterior interorbital pore (D) present; curved canine tooth at middle of side of lower jaw; pelvic fins flat and dish-like in adults (cup-like in 13.6-mm paratype); pelvic frenum with anteriorly-facing pocket; caudal fin truncate to rounded; numerous dark brown dots only on ventral half of body posterior to abdomen in preserved specimens; dorsal half of body transparent in life with seven saddle-like, pink and black bars (including one on nape), lower half of body pink, suffused with some yellow, and densely blotched and dotted with black. A small species, the holotype largest, 19.4 mm SL.

Description. Dorsal-fin rays VI + I,8; anal-fin rays I,9; pectoral-fin rays 14 (15 in one paratype), upper three and lower three rays unbranched; longitudinal scale series 51 (34–52 in four paratypes); transverse scale rows 12 (10 in one paratype, 13 in one paratype); segmented caudal-fin rays 9+8; branched caudal-fin rays 6+5.

Body elongate and rather compressed; body depth at anus 13% SL (11–13%, average 12% in three paratypes); head length 29% SL (28–30%, average 29% in three paratypes); head width slightly greater than head depth; head depth 51% head length (44–47%, average 46% in three paratypes); eye large, placed laterally and extending slightly above dorsal profile, 34% head length (27–33%, average 30% in three paratypes); snout short, less than eye diameter (more than eye in one paratype), 31% (29–31%) head length, and roughly rectangular in dorsal view; dorsal profile of snout concave before eye and convex above upper lip. Jaws slightly oblique and reaching posteriorly to below anterior half of eye; jaws same length (lower jaw slightly protruding in three paratypes); lower jaw rounded in ventral view. Tongue trilobed. Gill opening wide, reaching anteroventrally to below posterior edge of eye.

The following dental characters are based on largest paratype of BPBM 35724: teeth in both jaws conical, inwardly curved; upper jaw with three rows of teeth; outer row with five large teeth; inner rows with small teeth; lower jaw with three rows of teeth anteriorly, four rows centrally, and a single row posteriorly; outer row with seven large teeth; inner two rows with small teeth; innermost row with two large teeth preceding 18 medium-sized teeth.

Cephalic sensory system shown in Fig. 1 . Anterior oculoscapular-canal pores B', C, D, E, F, G' single, except D double in one 13.6-mm paratype; three preopercular-canal pores, M', N and O'.

Scales ctenoid; scales dorsally on body reaching forward below second dorsal-fin to end of first dorsal fin (reaching to below origin of second dorsal fin in a paratype, below end of second dorsal fin in two paratypes), and laterally reaching forward to above base of pectoral fin (nearly reaching to above base of pectoral fin in two paratypes, to below base of sixth spine of first dorsal fin in a paratype); head, breast, abdomen, base and axil of pectoral fins, and dorsal part of body below first dorsal fin naked (a narrow naked zone below second dorsal fin in two paratypes).

Species B. discus B. spongicolus Cat. No. BPBM 35695 BPBM 35724-1 BPBM 35724-2 USNM 398716 BPBM 41004 Type Holotype Paratypes Holotype Sex Male Male Female Female Male

First dorsal fin VI VI VI VI VI

Second dorsal fin I, 8 I, 8 I, 8 I, 8 I, 8

Anal fin I, 9 I, 9 I, 9 I, 9 I, 8

Pectoral fin* iii+8+iii iii+8+iii iii+8+iii iii+9+iii iii+12 Pelvic fin I, 5 I, 5 I, 5 I, 5 I, 5

Segmented rays of caudal fin 9+8 9+8 9+8 9+8 9+8

Branched rays of caudal fin 6+5 6+5 6+5 6+5 6+5

Longitudinal scales series 51 52 34 47 52

Transverse scales rows backward 12 13 10 12 11

mm % in SL mm % in SL mm % in SL mm % in SL mm % in SL

Standardlength 19.4 18.7 13.6 17.7 26.1

Head length 5.7 29% 5.7 30% 3.9 28% 5.3 30% 7.1 27% Head depth 2.9 15% 2.6 14% 1.7 13% 2.5 14% 3.6 14% Head width 3.1 16% 3.4 18% 1.9 14% 2.6 15% 3.9 15% Body depth of anus 2.5 13% 2.2 12% 1.4 11% 2.2 13% 3.9 15% Caudal-peduncle length 3.7 19% 3.7 20% 2.7 20% 3.3 19% 5.7 22% Caudal-peduncle depth 1.4 7% 1.4 8% 1.0 7% 1.3 7% 2.2 9% Pectoral fin length 4.1 21% 3.7 20% 2.7 20% 3.6 20% 4.3 17% Pelvic fin length 3.1 16% 2.9 15% 1.7 13% 2.5 14% 5.3 20% Caudal fin length 3.6 18% 3.4 18% 2.4 18% 3.3 19% 4.9 19% Snout length 1.7 9% 1.7 9% 1.2 9% 1.5 9% 2.9 11% Eye diameter 1.9 10% 1.5 8% 1.2 9% 1.7 10% 2.0 8% Upper jaw length 2.4 12% 2.4 13% 1.5 11% 2.2 13% 3.5 13% Fleshy interorbital width 0.9 4% 0.6 3% 0.5 4% 0.7 4% 1.2 4%

% in HL % in HL % in HL % in HL % in HL Snout length 31% 31% 30% 29% 41%

Eye diameter 34% 27% 30% 33% 28%

Upper jaw length 42% 42% 40% 42% 49%

Fleshy interorbital width 15% 10% 13% 13% 16%

Counts and Measurements follow Larson (1985). *: iii indicate three unbranched rays

First dorsal fin triangular, the third spine longest (second spine longest in two paratypes) second dorsal fin equal to first dorsal fin in height anteriorly, lower posteriorly; anal fin higher anteriorly, lower than second dorsal fin; caudal fin truncate to rounded; pelvic fins 16% SL (13–15%, average 14% in four paratypes), dish-like (cuplike in 13.6-mm paratype), not reaching anus; pelvic fins with an anteriorly-facing pocket; pectoral fins oblong, reaching past end of pelvic fins.

Color of holotype in preservative ( Fig. 2 ): head and body yellowish white; ventral half of pectoral-fin base, abdomen, and ventral half of caudal peduncle with many dark brown dots.

Color of paratype in life (BPBM 35724: Fig. 3 ): dorsal half of body and nape transparent with seven broad pink bars containing black blotches, the first on nape extending ventrally to operculum, second under predorsal region, third under rear of first dorsal fin, fourth under anterior half of second dorsal fin, fifth under posterior half of second dorsal fin, sixth on anterior half of caudal peduncle, and seventh on posterior half of caudal peduncle; a pink and black blotch in occipital region; lower half of body deep pink, suffused with a little yellow and densely blotched and dotted with black; lower half of head pink with scattered small black spots; upper half of iris bright red with some yellow dots and a yellow margin on dorsal half of pupil; a white line along dorsal part of vertebral column interrupted by pink and black bars to form a series of eight dashes; all fins translucent pink.

Distribution. Presently known from specimens from the Suakin Archipelago off Sudan, and the Seven Brothers Islands (Sawabi Islands) in the Gulf of Aden near the southern end of the Red Sea.

Etymology. The species name discus is from the Latin meaning dish or dish-like, in reference to the flat pelvic fins of adults.

Remarks. Bryaninops discus is most closely related to B. loki Larson , differing principally in having dish-like instead of cup-like pelvic fins in adults, numerous dark brown dots only ventrally on the body posterior to the abdomen in preserved specimens, and in having distinct pink and black saddle-like bars dorsally on the body in life. It also differs in having a slightly more slender body, 12.3% SL, compared to 13.6% in B. loki .

In her description of Bryaninops loki, Larson (1985) noted that most specimens have a dark blotch at the base of the lowermost caudal rays. We have examined the ten paratypes of B. loki of ROM 42738 from the Chagos Archipelago and the six paratypes of BPBM 29316 from the Great Barrier Reef and note that this blotch has faded or is represented by only a few dark dots (as seen in Fig. 8 ).

Randall (1994) misidentified this species as B. erythrops from two specimens from the Gulf of Aden, here included as paratypes of B. discus .

Comparative material. Bryaninops loki , BPBM 29316, paratypes, 6: 9–20 mm, Great Barrier Reef, Linnet Reef, 22 November 1975; ROM 42738, paratypes, 10: 9–19 mm SL, Chagos Archipelago, Salomon Atoll, 21 March 1979.

Figures

FIGURE 1. Head of holotype of Bryaninops discus sp. nov. showing cephalic sensory pores and papillae. Top: dorsal view; middle: lateral view; bottom: ventral view. Letters indicate sensory canal pores, and prime marks the terminal pores; (S) means a single pore; AN: anterior nasal pore; PN: posterior nasal pore. Dots represent the sensory papillae. Arrow shows position where gill membranes are attached to isthmus. Drawing by T. Suzuki.

FIGURE 2. Holotype of Bryaninops discus, 19.4 mm SL, Saunder's Reef, Suakin Archipelago, Sudan. Photo by T. Suzuki.

FIGURE 3. Paratype of Bryaninops discus sp. nov., BPBM 35724, 18.7 mm SL, Rhounda Komaxtou, Seven Brothers Islands, Gulf of Aden. Photo by J. E. Randall.

FIGURE 8. Bryaninops loki, paratype, ROM 42738, 15.3 mm SL, Chagos Archipelago. Photo by T. Suzuki.