Siphamia arabica, Gon & Allen, 2012

Gon, Ofer & Allen, Gerald R., 2012, 3294, Zootaxa 3294, pp. 1-84 : 17-20

Siphamia arabica new species

Figure 9; Table 5

Holotype: WAM P.26460-006 (originally part of WAM P.26460-014), 33.9 mm, female, United Arab Emirates, north of Khawr al Fakkan, 26º37’N, 56º21’E, 3–5 m, station FAO-77-0, G. R. Allen, 16 March 1977.

Paratypes: BPBM 21439 , 4 : 15.7–29.3 mm, Oman, off Khairan Island (32 km south of Masqat, 23º37’N, 58º34’E, 16 m, W.F. Smith-Vaniz, 13 March 1977; AMS I.45070-001, 17.9 mm and SAIAB 85932 , 18.3 mm, both females and originally part of BPBM 21439 ; WAM P.26460-014, 3: 24.0– 33.6 mm, collected with the holotype; CAS 228604 , 31.8 mm, ROM 84959, 33 mm and USNM 396989 , 29.0 mm, all females and originally part of WAM P.26460-014; WAM P.26461-016, 2: 21.2–22.3 mm, United Arab Emirates, north of Khawr Fakkan , 26º37’N, 56º21’E, 3–5 m, station FAO-77-0, G. R. Allen, 17 March 1977; WAM P.25785-001, 3: 17.7–23.0 mm, collected with BPBM 21439 .

Diagnosis: Dorsal rays VII+I,9; anal rays II,8; pectoral rays 15–16 (rarely 14); tubed lateral-line scales 6–10; median predorsal scales 3–4; total gill rakers 3–4 + 7–9 = 10–12; developed gill rakers 1 + 6–8; gill rakers on ceratobranchial 6–7. Body depth 2.4–2.6 in SL and body width 2.0– 2.1 in the depth; eye diameter 2.9–3.25 in head length; first dorsal spine 2.5–6.4 in second spine; second dorsal spine 3.5–4.6, spine of second dorsal fin 4.0–5.2, and second anal spine 5.4–7.3, all in head length; pectoral-fin length 4.7–5.5 and pelvic-fin length 4.25–4.7 in SL; caudalpeduncle length 1.8–2.3 in distance between pelvic spine insertion and anal-fin origin. Preopercular edge with 25–35 small serrations along its posterior and ventral edge, largest serrations at angle; preopercular ridge smooth. Tip of light organ on each side of tongue bound by membrane.

Colour in life: unknown.

Colour when fresh (from colour slide by J.E. Randall): cream white to pale brown with dark brown dots of various sizes, but dark brown between eyes and on occiput; jaws, snout and posterior part of caudal peduncle translucent with reddish brown dots; base of dorsal fins blackish; first dorsal fin spines, except first spine, reddish brown; proximal part of second dorsal-fin rays reddish brown; anal-fin rays with similar, but less distinct pigment; pelvic-fin base black; pelvic-fin spine reddish brown, the rays only faintly so; distal part of caudal-fin rays faintly pinkish.

Colour in alcohol: body usually dark brown with a variable amount of darker dots of various sizes; snout and jaws frequently paler; pale areas spread irregularly on body may be present; a line of somewhat larger dark dots usually present along middle of caudal peduncle, sometimes extending forward to head; first dorsal-fin spines with dark dots, but membrane between them largely pale; pelvic-fin base dark brown and pelvic spine with dark dots; other fins pale; indistinct mark on cheek from ventral edge of eye to angle of preopercular ridge; faint dark line from anterior end of preopercular ridge, under maxilla, to about ventral edge of infraorbital; dark pigment usually present along ventral edge and lower posterior edge of preopercular ridge; branchiostegal rays with small dark dots; peritoneum with dark dots of various sizes; intestine and stomach mostly pale with scattered minute dark dots; light organ along ventral margin of body and caudal peduncle with dark striation.

Smallest specimen, BPBM 21439 , 15.7 mm, and largest specimen examined, WAM P.26460-006, 33.9 mm, both from the Gulf of Oman (see list of types above for details) .

Description: Proportional measurements of the holotype and selected paratypes are given in Table 5. Dorsal rays VII+I,9; anal rays II,8; last soft ray of dorsal and anal fins branched to base; pectoral rays 15 (15–16), two upper and lowermost rays unbranched; pelvic rays I,5, all soft rays branched; principal caudal rays 17, upper and lowermost rays unbranched; upper and lower procurrent caudal rays 7 (7–8); tubed lateral-line scales 9 (6–10); vertical scale rows 23–24; horizontal scale rows at level of second dorsal fin origin 7; median predorsal scales 3 (3–4); circumpeduncular scales 12; developed gill rakers 1 + 7 (1 + 6–8); gill rakers on ceratobranchial 6 (6–7); branchiostegal rays 7.

Body deep and compressed, its depth 2.45 (2.4–2.6) in SL and its width 2.0 (2.0–2.1) in depth; head length 2.3 (2.3–2.5) in SL; snout length 5.1 (4.9–5.7), eye diameter 3.2 (2.9–3.25), and interorbital space, slightly convex, 4.3 (4.3–4.6), all in head length.

Mouth terminal, oblique and large; maxilla reaching posteriorly to vertical at about mid-distance between rear edges of pupil and eye respectively (to rear edge of eye in one specimen); upper jaw length 2.0 (1.9–2.0) and lower jaw 1.7 (1.7–1.8) in head length; both jaws with band of small, conical teeth; upper jaw band with 2–3 series at symphysis, increasing to about 6 series at middle of jaw; lower jaw band with 3–4 series at symphysis tapering to 2 series posteriorly; inner series teeth of both jaws somewhat enlarged; vomer with 2 series of small conical teeth anteriorly, tapering to single series on arms; palatines with small, conical teeth arranged in single series at both ends and 2 series in middle of bone (see Remarks for variation).

Rear nostril close in front of eye at level of dorsal edge of pupil, its vertical diameter about 4 times in pupil diameter; anterior nostril slightly larger, with slightly raised fleshy rim, at level of middle of eye and closer to tip of snout than to rear nostril.

Preopercular edge almost completely serrate; serrations 32 (25–35), small, farther apart from each other on ventral edge and largest around angle; preopercular ridge smooth; exposed edge of posttemporal smooth (1–3 minute serrations in some paratypes).

Body scales large, thin and easily shed; scales spinoid on predorsal area, along upper part of body and on upper and lower margins of caudal peduncle; body scales below lateral line with very few minute or no spines; tubed lateral-line scales with vertical line of minute papillae along middle of scale above and below tube, and short horizontal line of papillae along dorsal edge of tube ( Fig. 4a); tubeless scales with round to ovate cluster of papillae in place of tube; caudal fin with low scaly sheath of 2–3 scale series across its base; other fins without scales or scaly sheath.

Dorsal-fin origin over third lateral-line scale and slightly behind vertical through upper pectoral-fin base; first dorsal spine 2.9 (2.5–4.0) in second spine; second dorsal spine 4.2 (3.5–4.6) and third dorsal spine longest 2.4 (2.0–2.5) in head length; spine of second dorsal fin 4.4 (4.2–5.2) and longest dorsal soft ray 1.9 (1.9–2.2) in head length; first anal spine 2.9 (1.9–2.7) in second spine, and second anal spine 7.3 (5.4–6.9) and longest anal ray 2.65 (2.3–2.5) in head length; pectoral and pelvic fins not reaching anus; pectoral fin length 5.5 (4.7–5.2) in SL; pelvic fin origin on vertical though upper pectoral-fin base (slightly in front in some paratypes); pelvic fin length 4.4 (4.25–4.6) in SL and pelvic spine length 1.5 (1.4–1.7) in fin’s length; caudal fin emarginate, 4.1 (3.95–4.3) in SL.

Dorsal profile of head straight, predorsal distance 2.35 (2.2–2.4), preanal distance 1.4 and prepelvic distance 2.45 (2.5–2.7) in SL; caudal peduncle depth 1.3 (1.3–1.8) in its length, and the length 2.3 (1.8–2.3) in distance between pelvic-fin base and anal-fin origin; latter distance 2.8 (2.8–3.0) in SL.

Colour in alcohol: dark brown, paler on abdomen, snout and jaw, peppered with darker dots of various sizes; larger, expanded dots along middle of body; indistinct cheek mark from ventral edge of eye diagonally to angle of preopercular ridge; faint dark line from anterior end of cheek mark to anterior end of preopercular ridge; dark pigment along margin of preopercular ridge and on branchiostegal rays; palate pale; spines of first dorsal and pelvic fins with dark brown dots, the membrane largely pale; other fins pale; peritoneum with dense large, expanded melanophores; intestine and stomach with scattered small dark dots, fewer between anus and second intestinal loop.

Remarks: See Tables 1–3 for frequency distributions of pectoral rays, lateral-line scales and gill rakers. Five (of 14) specimens had three median predorsal scales. In these fish the smaller number of scales does not represent a shorter scaled predorsum. The fourth scale is replaced by a larger body scale that reaches over to the other side of the back. The number and arrangement of the teeth on the palatines is variable between specimens and sometimes on both sides of the same fish. Individuals 17.5 mm or smaller have a single series of teeth, often in distinct groups of 2 or 3 teeth. The smallest specimen with two series of teeth was 17.7 mm and the second series appeared on the posterior half of the bone. Only one fish had the second series of teeth on the anterior half of the palatines. Pigmentation of the internal organs is rather sparse; in this species and in some specimens the posterior part of the intestine is pale.

Siphamia arabica is a member of the S. tubifer species group. Within this group it shares a similar range of lateral-line scale counts with S. mossambica , S. stenotes , S. fraseri and S. randalli ( Table 2). S. arabica has lowest number of developed gill rakers (total and on the ceratobranchial, see Table 3) of all these species. While S. mossambica and S. arabica are western Indian Ocean species, S. stenotes , S. fraseri and S. randalli occur in the western and southern Pacific Ocean. The former two species are modally different in lateral-line scale counts, but S. mossambica also differs in having a shorter pelvic-fin spine (1.7–1.9 in pelvic fin length), a lower first dorsal fin (third spine 2.4–3.0 in head length) and a longer caudal fin (3.3–3.7) in SL. S. arabica is also similar to S. goreni from the southern Red Sea. See Remarks for the latter species below for a comparison of these two species.

All our specimens of this species were collected in the Arabian Peninsula coast of the Gulf of Oman ( Fig. 7) at depths of 3–16 m. At least one lot ( BPBM 21439 ) was found among the spines of a sea urchin. Randall (1995) illustrated this species as S. versicolor .

Etymology: This species is named arabica with reference to the Arabian Peninsula collecting locations ( Oman and United Arab Emirates) of the type specimens.