Siphamia roseigaster (Ramsay and Ogilby)

Gon, Ofer & Allen, Gerald R., 2012, 3294, Zootaxa 3294, pp. 1-84 : 60-62

Siphamia roseigaster (Ramsay and Ogilby)

Figures 28c, 29

Apogon roseigaster Ramsay and Ogilby, 1887: 1101 (type locality, Parramatta River , NSW, Australia; lectotype, AMS I.881).

Diagnosis: Dorsal rays VI+I,10–11; anal rays II,9–11; pectoral rays 14 (rarely 13 or 15); tubed lateral-line scales 24 + 0–2; median predorsal scales 4; total gill rakers 4–6 + 10–14 = 15–20; developed gill rakers 2–3 + 10–12 = 13–15; gill rakers on ceratobranchial 8–9 (one of 49 with 10). Body depth 2.8–3.0 in SL, and body width 2.1–2.5 in the depth; eye diameter 3.6–4.1 in head length; first dorsal spine 1.3–1.6 in second spine; second dorsal spine 2.45–3.0, spine of second dorsal fin 3.5–4.2, and second anal spine 3.7–4.8, all in head length; pectoral-fin length 4.2–4.5 and pelvic-fin length 5.0– 6.1 in SL; caudal-peduncle length 1.2–1.4 in distance between pelvic spine insertion and anal-fin origin. Preopercular edge and ridge smooth, the ventral edge frequently crenulate. Palatines toothless (2 of 49 fish had one small tooth on one palatine). Scales large, thin and cycloid; lateral-line scales with vertical series of papillae. Tip of light organ on each side of tongue not bound by membrane.

Colour when fresh (from colour photo provided by M. McGrouther): pale, translucent with orange hue, particularly on head, along upper part of body, and on caudal peduncle and fin; body with minute dusky dots, larger on head; short dark stripe from tip of upper jaw to eye; a line of black dots along ventral part of infraorbital bone below eye; a band of faint dark dots from lower edge of eye to angle of preopercular ridge; edge of preopercular ridge blackish; midline of predorsal area blackish; dark dots along dorsal fin bases, denser along first dorsal base; a line of dark dots along middle of caudal peduncle, more distinct posteriorly, branching dorsally and ventrally along edge of hypural plate; branchiostegal rays with small dark dots; light organ a wide silvery stripe, narrowly edged in black, along ventral edge of body from pelvic fin base, tapering posteriorly and ending at about two thirds of caudal peduncle length; light organ overlaid with scattered small, faint dark dots; first dorsal fin with diagonal black stripe from base of first spine to distal part of fifth spine; dark stripe across middle of second dorsal and anal fins; stripe on anal fin gradually fading anteriorly; a dark dot at base of each second dorsal- and anal-fin ray; base of pelvic fin dark; peritoneum with dark dots of various sizes; stomach dusky; intestine dark brown.

Colour in alcohol: similar to the fresh colour above, but without the orange hue. See also Remarks below.

Smallest specimen examined 16.9 mm, from Darwin, Northern Territory, and largest specimen 56.0 mm, from Parramatta River estuary, New South Wales .

Remarks: See Tables 1, 3 for frequency distributions of pectoral rays and gill rakers. One specimen (of 40) had 11 rays in the second dorsal fin; variation in the number of anal-fin rays included one fish (of 39) with 9 rays and two with 11 rays. In preservative the dark stripe on the second dorsal and anal fins varied from a dark spot on the last fin ray or partial faint stripe to a distinct stripe, or it was completely absent. Frequently it was different on each of the fins of the same fish. The stripe on the second dorsal fin was usually darker and reaching farther forward. The intensity in both stripes was highest on the last fin rays and decreased anteriorly. The dark dots at the base of the second dorsal and anal-fin rays were also variable with dots absent from some or all rays. In some fish the line of dark dots along the middle of the caudal peduncle extended forward on body. Kuiter (1993: 153) and Kuiter and Kozawa (1999: 51) provided underwater photos of this species.

This species is a member of the S. tubulata species group. It differs from all other species of Siphamia in having more than nine rays in the second dorsal fin, more than 8 rays in the anal fin and cycloid scales. It is the only species of the genus in which the light organ in the mouth is not restricted anteriorly by a membrane. Within the S. tubulata group, preserved S. roseigaster of about 30 mm or smaller may be confused with S. cephalotes because both share a similar, high number of developed gill rakers ( Table 3). However, S. cephalotes has fewer second dorsal, anal and pectoral-fin rays (9, 8 and 13, respectively), and ctenoid scales. It is the largest species of the genus.

The name Apogon roseigaster first appeared in two identical untitled paragraphs, attributed to Ogilby (1886: viii and 1887: 1061) before the valid description by Ramsay and Ogilby (1887: 1101–1102). In both paragraphs S. roseigaster is described briefly as having "black lobes on each side of the tongue." However, all Siphamia have these dark lobes, but in all except S. roseigaster they are restricted by a membrane. Ogilby did not recognize this difference as evident from the presence of two different species in his type series. The five syntypes at MCZ are S. cephalotes (see Remarks for the latter species above). Ramsay and Ogilby (1887) described the first unique characters for S. roseigaster (high number of second dorsal and anal-fin rays, and absence of palatine teeth) and we regard their paper as the original description. In order to properly assign the name to the correct species we designate AMS I.881 (48.5 mm SL, D VI+I,10, A II,9, P 15/15, no palatine teeth) as the lectotype for this species. Paxton et al. (1989) followed by Eschmeyer (2009) considered AMS I.15254–5, presumably from the Parramatta River, New South Wales (type locality of S. roseigaster ), as paratypes of S. roseigaster . However, according to the register of the fish collection of AMS both lots were actually collected by David Stead in the Clarence River in 1903, and therefore cannot be paratypes.

Gomon et al (1994: 566) regarded the name Adenapogon woodi McCulloch as a synonym of S. roseigaster , but provided no explanation for their decision. The holotype of A. woodi (AMS I.15251) has 8 rays in the second dorsal and anal fins, 16 developed gill rakers and toothed palatines, all characteristic of S. cephalotes .

Siphamia roseigaster occurs from the Northwest Shelf, Western Australia ( Sainsbury et al. 1984: 339), along the north and east coast of Australia, south to Sydney Harbour, New South Wales ( Fig. 7). It is a schooling species ( Kuiter 1993: 153) usually found in estuaries and coastal habitat with rock and sandy to muddy substrate at depths of 1– 63 m. Ramsay and Ogilby (1887) noted that specimens collected during the second half of October and the first half of November were spawning. Munro (1960: 138) reported that the male incubates eggs in its mouth. We examined one male (CSIRO B348, 40.0 mm) with a cluster of eggs in the mouth.

Material examined: WESTERN AUSTRALIA: north of Collier Bay , CSIRO B2021 , 46.5 mm ; CSIRO B2032 , 23 : 27.4–46.3 mm; north of Vansittart Bay , CSIRO B2035 , 46.0 mm ; CSIRO B2052 , 28 : 35.6–50.7 mm. Joseph Bonaparte Gulf , NTM S.13381-002, 5: 47.2–50.1 mm. NORTHERN TERRITORY: Beagle Gulf, northeast of Charles Point , NTM S.13283-013, 6: 35.3–43.2 mm. Darwin Harbour , NTM S.13709-002, 14: 16.9–36.4 mm; NTM S.13714-004, 2: 36.5–38.7 mm. South Alligator River, Mud Island , NTM S.14481-003, 30.1 mm. Shoal Bay, Hope Inlet, King Creek , NTM S.10527-001, 6: 30.9–49.5 mm. Roper River Mouth , NTM S.14016-002, 46.2 mm. QUEENSLAND: Gulf of Carpentaria , AMS IB.7159, 45.6 mm; AMS IB.7160, 3: 36.3–40.6 mm; AMS I.15557- 136, 20: 36.0–59.0 mm; CSIRO B348 , 6 : 40.0– 54.3 mm. Port Clinton , AMS I.34397-009, 2: 45.0–48.0 mm. Gladstone , AMS I.19926-001, 4: 31.0–35.0 mm. Brisbane , ANSP 98711 , 58.0 mm . NEW SOUTH WALES: Tweed River, Lillies Bay , CSIRO A1087 , 54.5 mm ; CSIRO A1088 , 39.5 mm. Manning River, Smithtown , CSIRO A2138 , 46.1 mm. Port Stephens , CSIRO B3925 , 39.0 mm. Avalon, Taylor’s Point , CSIRO B3503 , 3 : 35.0–38.0 mm. Parramatta River , AMS I.881, 48.5 mm (lectotype) , AMS I.43752-001, 19: 32.0–56.0 mm (paralectotypes). Clarence River , AMNH 1738 , 2 : 42.4–43.2 mm ; AMS I.41858-011, 57.0 mm; AMS I.41858-020, 6: 45.0–61.0 mm.