Siphamia jebbi Allen

Gon, Ofer & Allen, Gerald R., 2012, 3294, Zootaxa 3294, pp. 1-84 : 49-51

Siphamia jebbi Allen

Figures 20c–e, 24

Siphamia jebbi Allen, 1993: 14 , fig. 7 (type locality, Padoz Reef , off Nagada Harbour, Madang, PNG; holotype, WAM P.30375-006).

Diagnosis: Dorsal rays VII+I,9; anal rays II,8; pectoral rays 13 (rarely 12 or 14), unbranched and compressed distally; tubed lateral-line scales 0–8; median predorsal scales 4–5; total gill rakers 3–5 + 8–11 = 12–15; developed gill rakers 2 + 8–10; gill rakers on ceratobranchial 7–8. Body ovate, its depth 2.2–2.4 in SL, and body width 1.9–2.7 in the depth; eye diameter 2.7–3.0 in head length; first dorsal spine 2.0– 6.3 in second spine; second dorsal spine 4.1–5.9, spine of second dorsal fin 3.2–4.2, and second anal spine 4.2–4.8, all in head length; pectoral-fin length 4.1–5.3 and pelvic-fin length 3.8–4.8 in SL; caudal-peduncle length 1.2–2.0 in distance between pelvic spine insertion and anal-fin origin. Preopercular ridge smooth, the edge usually fully serrate (16–29 serrations). Vomer and palatines with single series to narrow band of small teeth, that of the former in v-shape. Scales large, thin and deciduous, usually cycloid under and around pectoral fin, and spinoid on at least posterior half of body; lateral-line scales with vertical series of papillae. Light organ relatively short, ending on caudal peduncle at 1–2 scales beyond base of last anal-fin ray; tip of light organ on each side of tongue bound by membrane.

Colour in life (from underwater photos by G.R. Allen): body translucent white peppered with small dark dots mostly anteriorly on upper part of body, below and in front of first dorsal fin; body and head with dense orange dots and markings of variable size that form irregular horizontal lines on lower part of body ( Fig. 20c); fin spines orange and fin rays orange proximally; fin membrane pale; upper part of orbit sometimes with orange dots and pupil encircle by iridescent blue dots; interorbital space and nape with variable amount of dark brown pigment.

Colour when fresh (from colour photos by J.T. Williams): generally translucent white, sometimes silvery anteriorly; body peppered with small dark dots overlaid with variable amount of orange dots and dashes, usually fading out on caudal peduncle ( Fig. 20d); small dark dots posteriorly on premaxilla, and along branchiostegal rays; fins usually pale, occasionally with dark specks basally; light organ silvery with dark vertical or slanted striations.

Colour in alcohol: mainly pale yellowish tan with scattered inconspicuous pepper-like dark dots on side of body; side of head and anteroventral portion of body silvery; a dark diagonal band on cheek from ventral edge of eye to angle of preopercular ridge; a narrow blackish line from anterior end of preopercular ridge passing below end of maxilla to ventral edge of dark cheek band; silvery luminescent gland along belly, extending on to lowermost part of caudal peduncle, the gland covered by numerous dark striations, its dorsal edge darkly pigmented; fins translucent white; palate and dorsal surface of tongue with dense covering of dark dots; peritoneum with large, conspicuous dark brown dots; stomach and intestine with fewer, smaller dark dots.

Smallest specimen examined, USNM 341594 , 7.5 mm, from Tonga and largest specimen, the holotype, 22.0 mm, from Papua New Guinea .

Remarks: See Tables 1–3 for frequency distributions of pectoral rays, lateral-line scales and gill rakers. Only two specimens had a full complement of five median predorsal scales. The tubed lateral line is sometimes followed by several scales with vestigial tubes. The light organ of a 10.5 mm specimen ended posteriorly at the base of the last anal-fin ray.

This species belongs to the S. tubifer group, but is similar in general appearance to species of the S. tubulata group such as S. brevilux , S. fistulosa and S. senoui . However, it is easily distinguished from them by the vertical, dark striations on its light organ as opposed to scattered dots. Only one other species in the S. tubifer group, S. stenotes , shares two developed gill rakers on the upper limb of the first gill arch with S. jebbi , while both S. stenotes and S. argentea share a count of usually 13 pectoral-fin rays ( Tables 1, 3). Both species can be separated from S. jebbi by their colour pattern ( S. argentea has irregular dark markings above and below the lateral line and S. stenotes has two dark, horizontal lines on the body), as well as in having more tubed lateral-line scales ( Table 2) and modally lower ( S. argentea ) and higher ( S. stenotes ) total number of gill rakers ( Table 3). Siphamia jebbi also has the shortest light organ in its species group and is a relatively small species, rarely exceeding 20 mm SL. See Tables 1–3 for meristic differences with other species in this group.

Re-examination of the type series of S. jebbi at the WAM revealed that seven paratypes (WAM P.30337-006, 5: 16.4–23.8 mm; WAM P.30372-006, 14.4 mm; and WAM P.30376-019, 24.8 mm), all from Madang, Papua New Guinea, were formerly misidentified and are actually S. cyanophthalma . The photograph in Allen (1993: fig. 7) is one of the misidentified specimens and not the holotype. It clearly shows the two horizontal blue lines across the eye and the ventral yellow part of the iris that are characteristic for that species.

Siphamia jebbi has been collected thus far in the Philippines, Sabah, Indonesia ( Flores to West Papua), Federated States of Micronesia, Papua New Guinea, Western Australia (Rowley Shoals), Queensland, Caroline Islands (Pohnpei), Fiji, and Tonga ( Fig. 6). It occurs in sheltered waters of lagoons and bays, on silt, sand or rubble bottom with coral coverage varying from isolated knolls and patch reefs to fringing reef at depths between 0– 29 m. At Madang the second author observed it usually in groups of about 20–40 individuals and it was often sighted in close proximity to Siphamia corallicola among beds of the pocilloporid coral Seriatopora hystrix .

Material examined: PHILIPPINES: Bararin Island , Palawan Province , USNM 262446 , 4 : 13.8–17.0 mm. Siquijor Island, USNM 268145 , 4 : 11.3–18.0 mm ; USNM 357883 , 3 : 13.2–17.6 mm . MALAYSIA, SABAH: Darvel Bay, Pulau Gaya , USNM 339039 , 4 : 11.1–12.1 mm. Mabul Island , KPM-NI 1903 , 16.6 mm . INDONESIA: Borneo , RMNH 21043 , 17.2 mm. Maumere, Flores , BPBM 32117 , 3 : 10.5–15.9 mm. Batanta Island , Papua Province , USNM 262581 , 12 : 9.6–15.4 mm . PALAU: CAS 84296, 4 : 12.0- 16.7 mm ; ROM 77203, 15.3 mm . TIMOR SEA: Hibernia Reef , NTM S.13420-035, 6: 15.0–19.0 mm. FEDERATED STATES OF MICRONESIA: Yap , Ifalik Atoll, CAS 84291, 15.0 mm . PAPUA NEW GUINEA: D’Entrecasteaux Islands, Goodenough Island , USNM 249707 , 3 : 13.1–17.8 mm. Ninigo Islands, Ami Island , USNM 262336 , 18.4 mm. Kranket Island , USNM 262337 , 3 : 9.4–18.3 mm. Madang , AMS I.33356-001, 5: 14.3–21.3.0 mm (paratypes) ; USNM 323789 , 5 : 13.7–21.6 mm (paratypes) ; WAM P.30375-001, 20: 11.7–22.4 mm (paratypes) ; WAM P.30375-006, 22.0 mm (holotype). WESTERN AUSTRALIA: Rowley Shoals, Mermaid Reef , WAM P.27666-013, 2: 14.7–15.2 mm (paratypes). QUEENSLAND: Ashmore Reef , AMS I.33715-016, 13: 9.4–17.4 mm. Lizard Island , AMS I.18740- 058, 2: 12.5–12.7 mm; AMS I.18740-066, 8: 11.1–15.2 mm. Escape Reef , AMS I. 22581-021, 13.7 mm. FIJI: Suva Harbour , AMS I.18353-041, 8: 14.2–20.0 mm. Yanu-Yanu-Sao Island , ROM 43261, 24 : 10.6–18.6 mm. Ono Levu Island , USNM 262493 , 8.4 mm ; USNM 245643 , 55 : 9.2–18.5 mm. Totoya Island , USNM 245637 , 17 : 11.0– 17.2 mm ; USNM 245640 , 13 : 9.5–19.7 mm. Matuku Island , USNM 262472 , 12.1 mm ; USNM 245638 , 35 : 9.6–20.4 mm ; USNM, 245639, 2: 14.9–16.5 mm. WALLIS ISLANDS: Ila Uvea , USNM 369972 , 16.75 mm ; USNM 371169 , 46 : 8.8–17.8 mm ; USNM 373648 , 65 : 8.7–16.5 mm . TONGA: Vava’u Island , UNSM 341592 , 9.5 mm ; USNM 341593 , 8.5 mm ; USNM 374676 , 19 : 12.0– 18.4 mm. Lifuka Island , USNM 341590 , 3 : 15.2–20.7 mm. Mala Island , USNM 341594 , 96 : 7.5–18.5 mm. Tongatapu Island, USNM 341591 , 5 : 11.9–14.6 mm . CAROLINE ISLANDS: Pohnpei, USNM 223216 , 32 : 9.5–16.7 mm .