Thryssocypris wongrati, Grudpan & Grudpan, 2012

Grudpan, Chaiwut & Grudpan, Jarungjit, 2012, Thryssocypris wongrati, a new anchovy-like cyprinid (Cypriniformes) from the Chao Phraya basin, Thailand, Zootaxa 3586, pp. 228-235 : 229-232

Thryssocypris wongrati sp. nov.

( Figs. 1–3)

Holotype. CAS 234133 , 50.1 mm SL, Bang Nok Kra-Yang Village , Sap-Phaya , Chai-Nat, Chao Phraya River, 15º08’22.88’’N, 100º08’47.32’’E, 01 November 2008, C. Grudpan et al.

Paratypes. CAS 234134 , 46.4 mm SL, same data as holotype . MNHN 2012 – 0135 , 45.2 mm SL, same data as holotype . KUMF 8793 , 46.3 mm SL, Chao Phraya River mainstem in front of Chao Phraya Dam, Chainat, Thailand, 15º09’38.56’’N, 100º11’04.19’’E, 16 September 1997, C. Grudpan et al . KUMF 8794 , 7 , 42.7–42.8 mm SL, Chao Phraya River mainstem in front of Chao Phraya Dam, Chainat, Thailand, 15º09’38.56’’N, 10º11’04.19’’E, 16 September 1997, C. Grudpan et al . KUMF 8795 , 3 , 42.3–52.2 mm SL, mainstem of Chao Phraya River in front of Chao Phraya Dam, Chainat, Thailand, 7 July 1994, C. Grudpan et al . UNMF-P06995 , 4 , 39.0– 46.8 mm SL, same data as holotype . UNMF-P 06996 , 46.6 mm SL, Naresuan Dam , Promphiram, Phitsanulok, Nan River, 14º02’45’’N, 100º10’57.86’’E, 6 July 2009, G. Deein et al . RLIKU 1889 , 48.6 mm SL, Pra-Sauk , In-Buri , Sing-Buri, Chao Phraya River, 15º0.3’43.3’’N, 100º18’30.1’’E, 12 September 2008, S. Arbsuwan et al . RLIKU 1890 , 5 , 28.6–37.4mm SL, Chan-Nasutra irrigation canal, along road number 3251, km. 27, Sra-Jaeng , Bang-Rachan, Sing-Buri, 14º54’15.2’’N, 100º13’24.3’’E, 12 September 2008, S. Arbsuwan et al .

Diagnosis. Thryssocypris wongrati differs from all other species of Thryssocypris by having the origin of the dorsal fin behind the origin of the anal fin, 37–40 lateral-line scales, 16 circumpeduncular scales, and a dark spot at the base of the caudal fin. It is distinguished from T. smaragdinus in having the origin of the dorsal fin behind (vs. over or in front of) the origin of the anal fin and 16 (vs. 15) circumpeduncular scales, and from T. tonlesapensis and T. ornithosoma in having 37 – 40 (vs. 42–46) lateral-line scales and 39 – 41 (vs. 43 – 45) vertebrae. It further differs from T. ornithosoma by having a dark spot at the base of the caudal fin.

Description. Meristic and morphometric characters are given in Tables 1–4. Body elongate and compressed ( Figs.1, 2). Head length 17.8–25.0% SL. Snout conical, length 25.4–34.5% HL ( Table 4). Mouth terminal; maxilla extending well beyond anterior margin of eye ( Fig. 3). Scales thin, deciduous; 37–40 lateral-line scales ( Table 2), 23–25 predorsal scales, 16 circumpeduncular scales ( Table 1). Dorsal-fin rays 9–10; anal-fin rays 14–16; pectoralfin rays 11–12; pelvic-fin rays 7–9. Anal and dorsal fins closer to caudal fin than to head. Origin of anal fin in front of origin of dorsal fin. Caudal fin deeply forked, rounded tips ( Fig.1). Total vertebrae 39–41 ( Table 3).

Color. In life, T. wongrati has a clear yellow body with a wide metallic silver stripe along the side ( Fig. 1), a black spot on the caudal-fin base and black on the proximal portion of the medial caudal-fin rays ( Fig. 2). All fins are transparent. In 10% formalin, the body is dark brown.

Distribution. Thryssocypris wongrati occupies the lower part of the Chao Phraya Basin where it has been recorded from irrigation canals in Sing-Buri up to the most northern part of the basin in Nan River, Phitsanulok ( Fig. 4). In the upper part of Chao Phraya basin it is found in floodplain habitats ( Jutagate et al. 2011), irrigation canals, and the river mainstem.

Ecology. Most specimens of the new species were collected by large seines with small mesh (2 mm) from open water in the Chao Phraya River mainstem. Some specimens were captured in current in irrigation canals. Schools of this species were observed at the surface of the water, swimming very fast with other species such as Clupeiodes borneensis , Rasbora spp. , Barilius koratensis , Paralaubuca spp. and Discherodontus halei .

Etymology. T. wongrati is named in honor of Dr. Prachit Wongrat, who was our first teacher in ichthyology.

(̝) T. wongrati , (●) T. tonlesapensis , (․) T. smaragdinus , (ˑ) T. ornithostoma .

Records are based on material examined (hollow symbols). Type localities are solid symbols. Map is modified from the distribution map for Hypsibarbus in Southeast Asia by Rainboth (1996b).