Aulopareia koumansi ( Herre, 1937 )

Larson, Helen K. & Jaafar, Zeehan, 2022, A review of the gobiid fish genus Aulopareia (Gobiidae: Gobiinae) with description of a new species from Kuwait and discussion of the status of Gobius cyanomos Bleeker, Zootaxa 5155 (4), pp. 493-516 : 501-505

Aulopareia koumansi ( Herre, 1937)

( Figs 7–9 ; Tables 1–3 , 5 )

Gnatholepis koumansi Herre , in Herre & Myers, 1937: 39 ( Malacca Straits, 100 miles west of Singapore, off the northern coast of Sumatra, Indonesia).— Koumans 1940: 152 (coast of Sumatra, Singapore).

Acentrogobius herrei Koumans, 1940: 152 (replacement name for Gnatholepis koumansi Herre, 1937 ).

Aulopareia janetae Smith, 1945: 535 (Nakon Bay, off eastern coast of Peninsular Thailand).— Rainboth 1996: 198 (Gulf of Thailand to Vietnam; Mekong delta); Larson in Randall & Lim 2000: 635 (South China Sea); Larson & Murdy 2001: 3595 (western central Pacific); Tran et al. 2013: 137 (Vietnamese Mekong to Peninsular Thailand); Kottelat 2013: 400 (Nakon Bay, off east coast of Peninsular Thailand); Nagao Natural Environment Foundation 2021: 436 (Mekong Basin in Vietnam).

Aulopareia koumansi — Larson & Murdy 2001: 3595 (western central Pacific); Rainboth et al. 2012: 102, Fig. 2104 ( Vietnam, My Tho, mouth of Tien Gang).

Material examined. INDONESIA: Holotype of Gnatholepis koumansi, CAS 30959, 62 mm SL male, coast of Sumatra, 100 miles west of Singapore , 27 March 1934, coll. A. Herre. THAILAND: Holotype of Aulopareia janetae, USNM 119548, 58 mm SL male, Nakon Bay, Gulf of Siam , 22 July 1928, coll. H.M. Smith. Paratype of Aulopareia janetae, MCZ 37255, 51 mm SL male, Nakon Bay, Gulf of Siam , 22 July 1928, coll. H.M. Smith. NIFI unregistered, 41.5 mm SL male, Chantaburi estuary, 4-7 July 1989, coll. C. Vidthayanon. MALAYSIA: NTM S.16642-002, 45 mm SL female, Malacca Strait , 3° 15.165’E 101° 15.495’ N, 28 March 1998 , C. V. Chong and students; AMS I.27754-021, 61.5 mm SL male .

Diagnosis. A species of Aulopareia with second dorsal rays I,10; anal rays usually I,9; pectoral rays 18–20; lateral scales 25–28; TRB 9–11; predorsal scales 13–19; two preopercular pores present; cheek and opercle completely scaled, nape completely scaled, scales on nape same size as scales on body, no barbels on chin or underside of head; mental frenum flattened, without lobes; gill opening extending to under mid-opercle. Characteristic colour pattern of dark grey head and body with large black shoulder patch enclosing white spots and a distinct black spot on upper part of caudal fin near base.

Description. Based on six specimens, 41.5–62 mm SL. An asterisk indicates data for holotype of Gnatholepis koumansi ( Fig. 7 ).

First dorsal fin VI*; second dorsal fin I,10*; anal fin I,8*–9, pectoral fin rays 18–20 (19 in holotype); segmented caudal fin rays 17*, in 9/8 pattern (number of caudal fin rays attaching to upper and lower hypural plates respectively); branched caudal fin rays 7/6 (in 1) or 8/7* (in 4); lateral scales 25*–28; transverse scales back 9*–11; transverse scales forward 12*–13.5; predorsal scale count 13–19 (18 in holotype); circumpeduncular scales 12 (in 1).

Body compressed posteriorly, rounded anteriorly. Head rounded to slightly compressed, deeper than wide, HL 29.1–31.8% (mean 30.3%) of SL; head depth 63.9–77.0% (mean 68.8%) of HL; head width 62.3–68.4% (mean 64.9%) of HL; head profile rounded to slightly pointed, with distinct hump at snout. Mouth large, terminal, oblique, forming an angle of about 35° with body axis; lower lip and chin tip anteriormost; jaws reaching to anterior part of eye or to below mid-eye; upper jaw length 40.4–45.8% (mean 42.9%) of HL. Lips smooth; lower lip fused to underside of head on either side of mentum. Tongue small, rounded to bluntly rounded. Eyes rounded, dorsolateral, eye length 15.0–17.2% (mean 16.1%) of HL. Snout bluntly rounded in dorsal view, 22.5–28.4% (mean 24.7%) of HL; posterior nostril oval to triangular, placed close to anterior edge of eye; anterior nostril in broad low tube close to upper lip. Interorbital broad, flat, 20.7–25.3% (mean 23.0%) of HL. Gill opening extending forward under opercle, not reaching posterior preopercular edge. Body depth at anus 22.4–27.2% (mean 24.0%) of SL. Caudal peduncle compressed, length 22.2–22.6% (mean 22.5%) of SL; caudal peduncle depth 14.1–15.3% (mean 14.6%) of SL.

First dorsal fin pointed, triangular, third spine longest, spine tip just touching base of second dorsal fin spine when depressed; longest spine 20.8–21.2% (mean 21.0%) of SL. Second dorsal fin rays just reaching base of caudal fin. Anal fin rays falling well short of caudal fin when depressed. Pectoral fin short, oval, central rays longest, fin length 22.8–23.6% (mean 23.3%) of SL; all rays branched but for uppermost, posterior tip of fin just reaching to above anus. Pelvic fins fused with frenum, pelvic disc short, forming pointed oval, nearly equal in length to pectoral fin, 22.5–24.4% (mean 23.7%) in SL. Caudal fin short, rounded posteriorly, 28.2–31.0% (mean 30.1%) of SL.

Teeth in upper jaw in 3–4 rows across front, narrowing to 2–3 at side of jaw, with largest tooth at bend of jaw, outermost row of teeth largest, stout, curved and pointed and may be honey-brown in colour; teeth of innermost row teeth much smaller, sharp and evenly sized. Teeth in lower jaw similar to those in upper jaw.

Predorsal scales small, cycloid, extending into interorbital space; cheek covered with small cycloid scales including below papilla row d; opercle covered with cycloid scales; pectoral fin base with cycloid scales; prepelvic area with cycloid scales; scales on side of body ctenoid anteriorly to behind pectoral fin; belly with cycloid scales.

Sensory canals and pores. Sensory canals with nasal pore at level of each posterior nostril, no anterior interorbital pore, single posterior interorbital pore, no postorbital pore, long slit-like pore behind eye, pore at end of canal over preopercular margin and pores at each end of short canal over opercle; two preopercular pores present. Sensory papillae in longitudinal pattern; papilla rows on side of head on variably raised fleshy ridges ( Fig. 8 ).

Freshly dead colour. Based on photo of Malaysian specimen ( Fig. 9 ). Head and body brownish grey with snout and side of head darkest; five indistinct dark brown saddles on dorsum; breast and belly pale, almost whitish. Large triangular black blotch on side above pectoral fin, with about five rows of bright white spots within the blotch. All fins black to blackish, black spot near base of the upper part of caudal fin, black spot may have white rear margin. The Mekong Basin specimens illustrated in Nagao Natural Environment Foundation (2021) show quite a large roughly oval black blotch on upper part of the caudal fin.

Preserved colour. Head and body brownish with dark brown blotch above and behind pectoral fin base (rather faded but visible in type specimens of A. janetae ), blotch surrounding about four small round white spots; small dark brown spot or blotch on upper part of caudal fin, close to base; all fins brown to dark brown.

Distribution and Habitat: Known from trawl catch from shallow coastal habitats and brackish waters from Indonesia, Thailand, Vietnam, and Malaysia.

Remarks. Nagao Natural Environment Foundation (2021: 436) discusses A. janetae and A. koumansi but they use the name A. janetae due to colour pattern differences between the descriptions of Herre and Smith. In Herre’s (1937) description, the caudal fin of Gnatholepis koumansi is not described nor figured as having a black spot present, but this spot may be obscured in specimens with a black caudal fin (spot discernible in Fig. 9 ). That said, Herre states that the caudal fin is “dusky” with all other fins black, and available notes do not mention a dark caudal spot in the Gnatholepis koumansi holotype (which does not mean it was not there). In contrast, Smith (1945) described A. janetae as having a “blackish spot about size of eye at upper base of caudal fin, with a pale area posteriorly” but did not mention nor describe the black blotch above the pectoral-fin base. The caudal fin spot may vary among populations, but with limited material (we examined six specimens) we cannot comment further but use the oldest name available.

Figures

FIGURE 7. Aulopareia koumansi, composite photo of holotype of Gnatholepis koumansi Herre, 1937, CAS 30959, 62 mm SL male. Photograph courtesy of the California Academy of Sciences Ichthyology Department.

FIGURE 8. Sensory pores and papilla rows in Aulopareia koumansi, composite drawing made from CAS 30959, holotype of Gnatholepis koumansi, and MCZ 32755, paratype of Aulopareia janetae. Not all scales on side of head shown (for clarity).

FIGURE 9. Aulopareia koumansi, fresh specimen from Malaysia. Photograph by Gianluca Polgar.