Siphamia senoui, Gon & Allen, 2012

Gon, Ofer & Allen, Gerald R., 2012, 3294, Zootaxa 3294, pp. 1-84 : 62-65

Siphamia senoui new species

Figures 28d, 30; Table 11

Holotype: KPM-NI 5727 , 18.5 mm, female, Japan, Ryukyu Islands , Yaeyama Islands , Iriomote Island, Funauki Bay, 10–13 m, H. Senou, 19 November 1998.

Paratypes (all from Ryukyu Islands, Japan): KPM-NI 5683 , 18.2 mm, female, Yaeyama Islands , Iriomote Island, Funauki Bay, 35 m, H. Senou and K. Yano, 19 November 1998; KPM-NI 5684 , 16.1 mm, male; KPM-NI 5685 , 15.9 mm, male; KPM-NI 5688 , 14.8 mm, male; last three lots collected with KPM-NI 5683 ; KPM-NI 5741 , 3 : 16.1–17.4 mm, three males and two females, collected with holotype; KPM-NI 16389 , 18.4 mm, male, Amami Islands , Amami ō Shima, Setouchi, S. Sato, 19 November 1998; NSMT-P 31454 , 18.7 mm, female, Amami Islands , Amami ō Shima , ō Shima Strait, Sakinome Beach, 28°11.2’N, 129°16.5'E, 15 m, quinaldine, M. Aizawa, 14 September 1989; NSMT-P 34928 , 2 : 10.3–13.5 mm, juvenile and female, Amami Islands , Amami ō Shima, Atetsu, 28°11.1’N, 129°17.5'E, 10 m, quinaldine, K. Matsuura and M. Aizawa, 12 June 1991; SAIAB 85931 , 18.3 mm, female and USNM 396991 , 16.35 mm, both originally from KPM-NI 5688 ; BMNH 2009.11 .27.3, 16.3 mm, male and WAM P. 33143-001, 17.4 mm, female, both originally from KPM-NI 5741 .

Diagnosis: Dorsal rays VII+I,9; anal rays II,8; pectoral rays 12 (rarely 11 or 13); tubed lateral-line scales 3–8; median predorsal scales 4–5; total gill rakers 3–4 + 9–11 = 12–14; developed gill rakers 1–2 + 8–9; gill rakers on ceratobranchial 6–7. Body depth 2.3–2.7 in SL and body width 1.95–2.25 in the depth; eye diameter 2.65–3.1 in head length; first dorsal spine 2.3–10.3 in second spine; second dorsal spine 4.35–6.2, spine of second dorsal fin 3.5–4.4, and second anal spine 4.7–5.6, all in head length; pectoral-fin length 4.4–4.95 and pelvic-fin length 4.1–4.9 in SL; caudal-peduncle length 1.1–1.5 in distance between pelvic spine insertion and anal-fin origin. Preopercular edge weakly serrate around angle, with 4–15 (usually 7–12) minute serrations; preopercular ridge smooth. Tip of light organ on each side of tongue bound by membrane.

Colour in life: unknown.

Colour when fresh (from colour slides by H. Senou): translucent with purplish tinge; body and head covered with small, brown to orange-brown dots of various sizes; dots sometimes joined along scale edges below lateral line on anterior part of body; posterior part of premaxilla dusky to black; pigment on iris variable, from faint brown on posterior and lower part to dense orange pigment all around; branchiostegal rays black or with dark dots; bases of at least first four spines of first dorsal fin, and spines of second dorsal, anal and pelvic fins blackish (see also Remarks below); light organ silvery with dark dots and with dark brown to black edge at least dorsally.

Colour in alcohol: body pale, peppered with small dark dots extending anteriorly to middle of interorbital space, and posteriorly to below second dorsal fin, occasionally to anterior part of caudal peduncle; dots sometimes form two bands, one on each side of lateral line; a series of small dark dots posteriorly on maxilla and lower jaw; triangular mark or band of dark dots from ventral edge of eye, usually tapering posteriorly to angle of preopercular ridge; another line of dots from anterior end of previous band to anterior end of preopercular ridge, and line of similar dots along ventral edge of preopercular ridge; dark dots sometimes present on area between upper end of preopercular ridge and ventral edge of posttemporal; branchiostegal rays and pectoral-fin base with dark dots; area between pectoral-fin base and light organ pale; pelvic-fin base dark brown; chest, isthmus, lower gill chamber and usually gill rakers on upper limb of first gill arch with dark dots; palate with variable amount of dark dots; surface of tongue with dark dots; iris variable, from silvery with narrow dark area anterodorsally to dark brown ring encircling pupil; fins pale, but area around bases of first and second dorsal-fin spines may be dusky; dark dots sometimes present at base of first anal-fin spine; light organ pale, silvery with small dark dots, sometimes edged dorsally with a dark line or a series of relatively large dark dots; peritoneum, intestine and stomach with large, blackish dots, but area of intestine between anus and closest loop with variable amount of dark pigment.

Description: Proportional measurements of the holotype and selected paratypes are given in Table 11. Dorsal rays VII+I,9; anal rays II,8; last soft ray of dorsal and anal fins branched to base; pectoral rays 12 (11–13), 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 and 6, respectively (7 and 5–7); tubed lateral-line scales 7 (2–8); vertical scale rows 24; horizontal scale rows at level of second dorsal fin origin 7 (6–7); median predorsal scales 5 (4–5); circumpeduncular scales 12 (10–12); developed gill rakers 2 + 9 (1 + 8–9); gill rakers on ceratobranchial 7 (6–7); branchiostegal rays 7.

Body deep and compressed, its depth 2.5 (2.3–2.7) in SL and its width 2.0 (1.95–2.25) in depth; head length 2.2 (2.0–2.4) in SL; snout length 7.95 (6.7–9.2) and eye diameter 2.9 (2.65–3.1) in head length; interorbital width 5.4 (4.3–5.8) in head length.

Mouth terminal, oblique and large; maxilla reaching posteriorly to vertical at mid-distance between posterior edges of pupil and eye, respectively (to below edge of pupil in most paratypes) and its posterior (vertical) edge slightly indented; upper jaw length 1.9 (1.9–2.0) and lower jaw 1.6 (1.6–1.7) in head length; both jaws with band of small, conical teeth; upper jaw band with 2 series at symphysis, increasing to about 5 series at middle of jaw; lower jaw band with 4 (3–5) series at symphysis tapering to 2 series posteriorly; inner series teeth of both jaws enlarged, but symphyseal teeth of lower jaw sometimes larger; vomer and palatines with single series.

Rear nostril ovate, close in front of eye, its lower edge at level of dorsal edge of pupil (at mid-body level in some paratypes), its long diameter about 4.0 (2.5–3.0) times in pupil diameter; anterior nostril slightly ovate, its long diameter about three quarters of rear nostril’s (almost as long as rear nostril in some paratypes), with slightly raised rim, at level of middle of eye and closer to rear nostril than to tip of snout (midway between the two in some paratypes).

Preopercular edge with 11 (4–15) minute serrations around angle; preopercular ridge smooth; exposed edge of posttemporal with 3 small, blunt serrations (1–4, usually pointed in paratypes).

Scales large, very thin, soft and easily detached; scales spinoid, those under pectoral fin with few or no spines (most paratypes missing many scales); 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; caudal fin with low scaly sheath of 2 scale series across its base; other fins without scales or scaly sheath.

Dorsal-fin origin slightly behind vertical through upper pectoral-fin base; first dorsal spine short (2.3–6.2 in second spine); second dorsal spine broken (4.35–6.2), and third dorsal spine, longest, 3.0 (2.8–3.5) in head length; spine of second dorsal fin 3.5 (3.5–4.5) and longest dorsal soft ray 2.0 (2.1–2.5) in head length; first anal spine 2.8 (3.1–6.6) in second spine; second anal spine 4.9 (4.7–5.6) and longest anal ray 2.6 (2.5–2.85) in head length; pectoral fin reaching posteriorly close to anal-fin origin, its length 4.5 (4.4–4.95) in SL; pelvic-fin origin slightly in front of vertical through upper pectoral-fin base, extending to anus, its length 4.6 (4.1–4.9) in SL; pelvic-fin spine length 1.5 (1.5–1.8) in fin’s length; caudal fin emarginate, 3.6 (3.25–3.7) in SL.

Dorsal profile of head slightly convex; predorsal distance 2.2 (2.1–2.3), preanal distance 1.5 (1.5–1.6) and prepelvic distance 2.45 (2.2–2.5) in SL; caudal peduncle depth 1.35 (1.2–1.7) in its length and the length 1.6 (1.1–1.5) in distance between pelvic-fin base and anal-fin origin; latter distance 4.1 (3.5–4.3) in SL.

Colour in life: unknown.

Colour when fresh (from colour slide by H. Senou): similar to the pattern diagnosed above; brown dots on body denser below first dorsal fin and on predorsal area; iris with faint brown dots behind and below pupil; pelvicfin base blackish.

Colour in alcohol: as diagnosed above; small dark dots on anterior part of body, mostly above lateral line, with some scattered below second dorsal fin base, and between midline of body and upper edge of pectoral fin; pelvicfin base dark brown; pelvic spine with several dark dots along inner edge; area of palate between middle of palatines with dark dots; iris silvery with dark brown ring encircling pupil; no dark dots around base of anterior dorsal and anal-fin spines.

Remarks: See Tables 1–3 for frequency distributions of pectoral rays, lateral-line scales and gill rakers. The presence of two developed gill rakers on the upper limb is unusual and occurred in a single fish that had only one developed gill raker on the gill arch of the right side. The holotype and several paratypes had a few minute teeth anteriorly on the palatines, and one paratype (KPM-NI 16389) had no teeth on these bones. One specimen (NSMT- P 31454) had vertical lines of papillae on the lateral-line scales as well as body scales. The base of the genital papilla of several males (KPM-NI 5741, 16389) had a ring of small dark dots. It is difficult to tell from colour photos of this species whether the fins have the brown-orange dots found in several other members of this species group, but faint dots seem to be present at least on the caudal fin of all the photographed specimens and on the dorsal fins of one fish. In addition, one specimen had orange-brown pigment proximally on pelvic-fin rays and faint dusky dots on pelvic-fin spine. The right eye of the holotype had a ring of dark brown pigment around the pupil, but this marking was absent on the left eye.

This species is a member of the S. tubulata species group. It seems to differ from other congeners, except S. fistulosa , in having a brownish orange (in life) or dark brown (in preservative) iris. In some preserved specimens the dark brown pigment of the iris was variable and did not completely encircle the pupil. Siphamia senoui is most similar to S. brevilux , S. cyanophthalma and S. fistulosa in body colour and morphometric characters. The first and the last mentioned species are modally different in tubed lateral-line scales ( Table 2) and also have a longer light organ ( Fig. 3c, see Remarks for S. brevilux for a comparison with this species). In addition, S. brevilux has modally fewer gill rakers ( Table 3). Live S. cyanophthalma differs in having the characteristic blue horizontal lines across the eye and preserved fish can be separated by their longer light organ (1.25–3.5 in caudal peduncle length versus 4.0– 21.3 in S. senoui ). Although S. tubulata shares the same pectoral-fin ray count ( Table 1), it has a complete or nearly complete, lateral line, modally fewer developed gill rakers ( Table 3), and its body is fully covered with dark dots and usually with irregular dark marks. Of the remaining species in this group, S. corallicola and S. elongata have fewer pectoral-fin rays ( Table 1), a more slender body (depth 2.6–3.3 in SL), shorter pectoral fins (5.1–6.1 in SL) and different body colour (see colour description in the relevant species account). See Tables 1–3 for differences from the three Australian endemics, S. cephalotes , S. cuneiceps and S. roseigaster .

In a 10.3 mm specimen the light organ reached the base of the third anal-fin ray and in a 13.5 mm female it extended slightly beyond the base of the last anal-fin ray.

This species is currently known only from the Ryukyu Islands ( Fig. 8) where it was collected at depths of 10– 30 m.

Etymology: This species is named senoui in honour of Dr. Hiroshi Senou of the Kanagawa Prefectural Museum of Natural History. Dr. Senou, in collaboration with various Japanese colleagues, has been largely responsible for a marked increase in our knowledge of tropical reef fishes occurring in southern Japan and the adjacent Ryukyu Archipelago. He also collected and photographed the holotype and most paratypes of this species.