Nemipterus andamanensis, Bineesh & Russell & Chandra, 2018

Bineesh, K. K., Russell, Barry C. & Chandra, K., 2018, Nemipterus andamanensis, a new nemipterid fish (Perciformes: Nemipteridae) from the Andaman Islands, Zootaxa 4500 (1), pp. 82-90 : 83-88

Nemipterus andamanensis n. sp.

New English name: Andaman Islands threadfin bream

Figures 1 , 2 , 3 ; Table 1

Holotype. ZSI/ANRC- 19225, 133.6 mm SL, Junglighat fish market, Port Blair, Trawl net, 1118.45"N; 9241.03"E, Cinque Island, south Andaman Islands, Andaman Sea, collected by K.K. Bineesh, 18 September 2017.

Paratypes. ZSI/ANRC- 19226, 133.4 mm SL, Junglighat fish market, Port Blair, Trawl net, south Andaman Islands, Andaman Sea, collected by K.K. Bineesh, 18 September 2017. ZSI/ANRC- 19227, 146.4 mm SL, Junglighat fish market, Port Blair, Trawl net, south Andaman Islands, Andaman Sea, collected by K.K. Bineesh, 18 September 2017. ZSI/ANRC-19870, 129.6– 139.8 mm SL, 5, Bathu Basti fish market, Port Blair, Trawl net, south Andaman Islands, Andaman Sea, collected by K.K. Bineesh, 3 March 2018.

Diagnosis. Pectoral fin rays 14‒16; gill rakers 10‒14; body moderately elongate; depth 3.4‒3.7 in SL. Head length equal to or a little more than body depth; diameter of eye a little less than snout length; 1.1‒1.4 in snout; lower margin of eye distinctly above a line from tip of snout to upper pectoral-fin base; suborbital moderately deep, its least depth 1.2‒1.6 in eye diameter; its lower margin slightly emarginate, least depth 1.2–1.7 in eye diameter; its posterior edge more or less straight, and an imaginary line extended upward from posterior edge reaching dorsal profile about 3–4 scale rows before origin of dorsal fin; pectoral fins long, reaching to or just beyond level of vent; pelvic fins very long, reaching to or almost to origin of anal fin; caudal fin forked, upper rays produced to form short thin filament.

Description. Counts and proportional measurements are provided in Table 1. Dorsal-fin rays X, 9; anal-fin rays III, 7; pectoral-fin rays 14(L)/15(R) (14–16); principal caudal-fin rays 18. Lateral-line scales 46 (45–48); transverse scale rows 2.5/8.5, total gill rakers 12 (10–14). Total vertebrae 24.

Body depth 3.5 (3.4–3.7) in SL; head length 3.2 (3.2–3.4) in SL; head length equal to or a little more than body depth, depth 1.1 (1.0–1.1) in head; snout short, slightly rounded in profile, 3.3 (2.8–3.1) in head; eye 3.6 (3.3–4.1) in head; diameter of eye a little less than snout length, 1.1 (1.1–1.4) in snout; lower margin of eye distinctly above a line from tip of snout to upper pectoral-fin base; interorbital narrow, its width 1.8 (1.4–2.1) in eye; least depth of suborbital 1.5 (1.2–1.6) in eye; ventral margin of suborbital slightly emarginate, its posterior edge more or less straight; an imaginary line extended upward from posterior edge reaching dorsal profile about 3–4 scale rows before origin of dorsal fin; margin of preopercle very weakly denticulate; caudal peduncle depth 1.3 (1.3–1.7) in peduncle length; dorsal-fin length 1.8 (1.8–1.9) in SL; fourth through tenth dorsal spines longest, 1.4 (1.2–1.9) times length of first dorsal spine; fifth or sixth dorsal rays longest, 1.6 (1.4–1.6) times length of longest dorsal spine; anal-fin length 5.1 (5.0–5.5) in SL; third anal-fin spine longest; first anal spine 2.4 (1.1–2.3) in second; second anal spine 1.1 (1.1–1.3) in third; pectoral fins long, reaching to or just beyond level of vent, 1.3 (1.0–1.4) in head; pelvic fins very long, reaching to or almost to origin of anal fin, 1.3 (1.1-1.2) in head; pectoral fins 1.0 (0.9– 1.2) in pelvic fins; caudal fin forked, upper rays produced to form short thin filament (broken in some specimens).

Maxillary reaching to below anterior margin of eye; jaw teeth small, pointed, in narrow tapering bands in both jaws; upper jaw with outer row of 3–4 pair of small, recurved canines anteriorly; lower jaw with outer row of slightly enlarged canines anteriorly; smaller canines laterally on either side of lower jaw.

Colouration when fresh ( Fig. 1 ): body silvery pink with yellowish tinges, a broad silvery band extending from above origin of pectoral fin to end of caudal peduncle. Ventral surface yellow; head with four golden yellow stripes, first one comparatively broad, indistinct yellow golden stripe, extending from rear tip of snout to anterior of eye; second oblique stripe originating from near middle of upper jaw to below eye and covering entire post orbital margin; interspace between these two stripes silvery white or mauve (becomes dusky in formalin); third stripe originating from just above upper jaw and extending to lower margin of preopercle; fourth stripe from posterior margin of preopercle to lower edge of opercle; upper lip pale mauve. Dorsal fin pale yellow with narrow bright yellow margin on spinous part; yellow stripe dividing at about tenth dorsal spine into three narrow. dusky stripes; second stripe originating at about tenth dorsal spine; first and third stripe originating at second and third dorsal rays respectively. Ventral fins pinkish; anal fin translucent with yellow submarginal stripe, and another yellow stripe a short distance from the base of fin; upper caudal fin yellow, colour extending to long filament; lower caudal fin pinkish; peritoneum yellow.

Colour in preservative: dusky broad band from anterior of snout to lower margin of eye; narrow black line on lower margin of eye; dusky upper lips; traces of three narrow dusky stripes on posterior half of dorsal fin; middle stripe long, originating from tenth dorsal spine ( Fig. 3 ).

Barcode sequences. We attempted to sequence all sympatric forms of Nemipterus found in the Indian waters. A 627 base pair amplicon from the 5´region of the mitochondrial COI gene was bidirectionally sequenced for the holotype and four paratypes. The holotype and four paratypes sequences were virtually identical (0.3 % sequence divergence). They possess a unique haplotype that is substantially divergent from all other Nemipterus species. The sequence of Nemipterus marginatus shows 8.5% genetic divergence with our sequences of Nemipterus andamanensis from South Andaman Islands. The tree revealed that Nemipterus andamanensis is distinct from other species of Nemipterus ( Fig. 6 ).

Etymology. The species name andamanensis is in reference to the Andaman Islands, the only known locality from which this species has been collected and recorded. The common name Andaman Islands threadfin bream is proposed for this species.

Distribution. Nemipterus andamanensis n. sp. is thus far known only from the Andaman Islands ( Fig. 5 ). Fishermen report it is common in depths of 20‒50 m, and it is often seen together with N. peronii , N. nematophorus and N. japonicus in the fish market at Port Blair, South Andaman Island. Nemipterus andamanensis n. sp. was not collected during recent trawl surveys in Myanmar waters of the eastern Andaman Sea by the RV Dr Fridtjof Nansen, suggesting it is probably endemic to the Andaman Islands.

Comparisons. Nemipterus andamanensis n. sp. superficially resembles N. marginatus ( Fig. 4 ) in colour pattern but differs from the latter by having two yellow stripes on the head region (from upper jaw to lower edge of preopercle, and on lower part of opercle); longer caudal filament (caudal filament short in N. marginatus ); and upper lobe of caudal fin and filament yellow, lower lobe of caudal fin pinkish (caudal fin and filament uniformly pinkish in N. marginatus ).

Comparative Material. Nemipterus marginatus . BMNH 1984.8.20: 11, 141.1 mm SL, S. coast of Lombok , Indonesia . CAS 29400, 2 :91.0–99.0 mm SL, Agusan Province , Mindanao, Philippines . CAS 48419, 116.5 mm SL, Gulf of Thailand . CSIRO 2510-2511 , 2 : 102.3-110.2 mm SL, Arafura Sea , Australia . MNHN 9055 , 64.1 mm SL (lectotype of Dentex marginatus Valenciennes ), Java, Indonesia . MNHN B. 2934, 101 mm SL (paralectotype of D. marginatus Valenciennes ), Vanikoro I., Santa Cruz Is , Solomon Islands . NTM S.10665-001, 3: 114–130 mm SL, Krankur fish market, Singapore . NTM S.10667-002, 2:130.0147.0 mm SL, Georgetown market, Penang, Malaysia . NTM S.10672-005, 140.8 mm SL, Phuket, Thailand . NTM S.10675-002, 140 mm SL, Bangkok, Thailand . NTM S.10677-021, 121 mm SL, Kota Kinabalu Sabah . NTM S.10678-004, 2: 100.2–130.7 mm SL, Kuching , Sarawak . NTM S.11005-001, 90.7 mm SL, S. coast Java, Indonesia . NTM S. 11021-001, 133.3 mm SL, S. of Yogyakarta, Java, Indonesia . NTM S. 11454-004, 85 mm SL, Port Essington , Northern Territory, Australia . NTM S.12371-003, 3:100.6‒120.0 mm SL Muara Angke fish landing Jakarta, Indonesia . NTM S. 18005, 147 mm SL, Ayeyarwadi Delta, Myanmar , RV Dr Fridtjof Nansen, bottom trawl . NTM S.18011-001, 142 mm SL, Tanintharyi Coast , Myanmar , RV Dr Fridtjof Nansen, bottom trawl . NTM S.18029-004, 2:135.0‒153.0 mm SL, Ranong fish market, Thailand . USNM 227082, 117.8 mm SL, Puerto Princessa market, Palawan, Philippines .

Figures

FIGURE 1. Holotype of Nemipterus andamanensis n. sp., ZSI/ANRC-19225, 133.6 mm SL.

FIGURE 2. Paratype of Nemipterus andamanensis n. sp., ZSI/ANRC-19226, 133.4 mm SL

FIGURE 3. Paratype of Nemipterus andamanensis n. sp., ZSI/ANRC-19227, 146.4 mm SL, after preservation.

FIGURE 4. Nemipterus marginatus, NTM S.18029-004, 153 mm SL, Ranong, Thailand.

FIGURE 5. Map of the Andaman & Nicobar Islands, showing the collection locality of Nemipterus andamanensis n. sp.

FIGURE 6. Kimura 2 parameter (K2P) distance neighbour-joining tree of cytochrome c oxidase (COI) sequences from the genus Nemipterus.