Siphamia guttulata (Alleyne and Macleay)

Gon, Ofer & Allen, Gerald R., 2012, 3294, Zootaxa 3294, pp. 1-84 : 48-49

Siphamia guttulata (Alleyne and Macleay)

Figure 23

Apogon guttulatus Alleyne and Macleay, 1877 , plate 5, fig.1 (type locality, Darnley Island, Torres Strait , Queensland; lectotype, AMS IA.8103.

Diagnosis: Dorsal rays VII+I,9; anal rays II,8; pectoral rays 15–16; tubed lateral-line scales 23–24; median predorsal scales 0–1; total gill rakers 3–4 + 9–10; developed gill rakers 1 + 7–8; gill rakers on ceratobranchial 7. Body depth 2.25–2.6 in SL and body width 1.8 in the depth; eye diameter 2.95–3.25 in head length; first dorsal spine 2.7–4.7 in second spine; second dorsal spine 4.2–6.2, spine of second dorsal fin 5.4–6.9, and second anal spine 5.4–6.4, all in head length; pectoral-fin length 4.6–5.4 and pelvic-fin length 3.8–4.4 in SL; caudal-peduncle length 1.7–1.9 in distance between pelvic spine insertion and anal-fin origin. Preopercular edge with 16–20 serrations around angle; preopercular ridge smooth. Scales spinoid; tubed lateral-line scales with vertical series of papillae. Vomer and palatine with 1–2 series of minute teeth, those of the palatines sometimes irregular. Light organ ending over middle procurrent caudal rays, its anterior tip on each side of tongue bound by membrane.

Colour in life: described by Alleyne and Macleay (1877) as follows: “Body silvery and speckled all over with minute black dots, with three longitudinal dark bands on each side, one from the top of the head to the termination of the dorsal fins; another, the largest, from the muzzle through the eye to the tail, the third from the suboperculum to the tail, marking the limits of a very silvery belly. The fins are whitish and very minutely speckled.”

Colour in alcohol: body brown on the back and silvery grey on the sides, covered with dark dots of various sizes; some specimens with traces of dark brown stripe along middle of body; anterior 3–4 dorsal spines with dark dots; fins otherwise pale; pelvic-fin base with dark dots; dark dots sometimes present on upper limb of first gill arch; palate with few scattered dark dots; peritoneum, stomach and intestine with dark dots of various sizes.

Smallest and largest specimens examined, AMS I.16306-001, 19.0 and 28.0 mm, respectively, from the type locality .

Remarks: See Tables 1–3 for frequency distributions of pectoral rays, lateral-line scales and gill rakers. Munro (1960) counted 8 soft rays in the second dorsal fin of this species, but all the specimens we examined had 9 rays in this fin.

This is a small, compact species that belongs to the S. tubifer species group. Initially we thought it was misidentified small specimens of S. tubifer as the two species share a complete lateral line, similar counts of developed gill rakers and a light organ that runs almost the full length of the caudal peduncle. However, radiographs of S. guttulata revealed that it has two supraneural bones, a character it shares with S. argentea , whereas all other members of the S. tubifer group have only one. It is also unique for the genus in having only one or no median predorsal scales. Gon and Randall (2003) found a similar situation in the genus Archamia in which A. buruensis had 1–2 median predorsal scales compared with 4–7 scales in other congeners.

We have found only two lots of specimens for this species, both at the Australian Museum, Sydney, and both are syntypes. Of these the 22.5 mm SL specimen in AMS IA.8103 is in relatively good condition, although it has a damaged caudal fin and two tubed lateral-line scales are missing on the left side. It is also unusual in having seven developed gill rakers on the lower part of the first gill arch. We designate this specimen as the lectotype of S. guttulata . The specimens in AMS I.16306 therefore become paralectotypes .

This species is known only from Darnley Island ( Fig. 8), the type locality, where it was found aggregating in rock crevices in shallow water. Smallest female with large gonad and eggs was 22.7 mm.

Material examined: QUEENSLAND: Torres Straits, Darnley Island , AMS IA.8103, 22.5 mm (lectotype); AMS I.16306-001, 31: 19.0–28.0 mm (paralectotypes) .