K. V. Akhilesh

Catch composition, reproductive biology and diet of the bramble shark Echinorhinus brucus (Squaliformes: Echinorhinidae) from the south‐eastern Arabian Sea

Fishery and biological data are presented for the poorly known bramble shark Echinorhinus brucus (Squaliformes: Echinorhinidae), from the deep waters of the south-eastern Arabian Sea. A total of 5318 individuals from by-catch landings of deep-water bottom set longlines, gillnets and shrimp trawl fisheries operating at depths of 200-1200 m were recorded between January 2008 and December 2011 at the Kochi Fisheries Harbour (Kerala). A total of 431 individuals, from 46 to 318 cm total length (L(T)) and 0·8 to 132 kg total mass (M(T)), were examined to determine biological data for this species. The LT at which 50% were mature (L(T)50) for females and males was estimated at 189 and 187 cm LT. Litter size ranged from 10 to 36 and size at birth was between 42 and 46 cm L(T). Dietary analysis of stomach contents revealed E. brucus feeds on a variety of prey including crustaceans (69% index of relative importance, I(RI)), teleosts (25·8% I(RI)), cephalopods (1·7% I(RI)) and elasmobranchs (0·7% I(RI)). This study provides the first detailed biological data for this species and also highlights the extent of the by-catch fishery for this species in Indian waters.

Biological observations on the bristly catshark Bythaelurus hispidus from deep waters off the south-west coast of India

Biological data are presented for the poorly known bristly catshark Bythaelurus hispidus based on specimens collected from the by-catch of the commercial deep-sea shrimp trawl fishery operating in the Arabian Sea at depths of 200-500 m off the south-west coast of India. One hundred and sixty-two individuals, which ranged from 120 to 366 mm total length (L(T)), were collected for this study. Size-at-maturity (L₅₀) for females and males was estimated at 252 and 235 mm L(T), respectively. The reproductive mode of B. hispidus was aplacental viviparity, which is the rarest reproductive mode within the Scyliorhinidae and is considered to be the most advanced of the three reproductive modes occurring within this family. Dietary analysis of stomach contents revealed B. hispidus feeds on a variety of prey, primarily fishes.

Report of crocodile shark Pseudocarcharias kamoharai (Pseudocarchariidae) from deep waters off the south-west coast of India

The crocodile shark, Pseudocarcharias kamoharai previously unknown from the Arabian Sea of India is reported from the south-western coast (Kerala). The specimen is described and figured.

Aspects of the biology of the pygmy ribbontail catshark Eridacnis radcliffei (Proscylliidae: Carcharhiniformes) from the south‐west coast of India

Biological data are presented for the pygmy ribbontail catshark Eridacnis radcliffei based on specimens collected from the by-catch of the commercial deep-sea shrimp trawl fishery operating in the Arabian Sea off the south-west coast of India. A total of 549 individuals, from 101 to 257 mm total length (L(T)) and 2·2 to 56 g, were collected. The L(T) at first maturity (L(T50)) of females and males was estimated at 183 and 170 mm, respectively, and analysis of stomach contents revealed that E. radcliffei feeds primarily on crustaceans.

Histological profiling of gonads depicting protandrous hermaphroditism in Eleutheronema tetradactylum

The fourfinger threadfin Eleutheronema tetradactylum is reported as a protandrous hermaphrodite from Australian waters, while being a gonochorist in reports from Singapore and India, with a single report of protandrous hermaphroditism from the latter. Histological analysis of gonads of fish from Indian waters confirms protandrous hermaphroditism in E. tetradactylum. The study was based on 480 fish examined from eight locations along the Indian coast. Mean total length (LT ) of male fish was 240 mm with the transition to female starting from 280 mm LT . Specimens confirmed as mature females were >380 mm LT .

Redescription of the rare and endangered Broadfin Shark Lamiopsis temminckii(Müller & Henle, 1839) (Carcharhiniformes:Carcharhinidae)from the northeastern Arabian Sea

The genus Lamiopsis (Carcharhinidae) was previously considered to be monotypic, containing only the Broadfin Shark Lamiopsis temminckii (Müller & Henle, 1839) widely distributed in the Indo-West Pacific. However, a recent taxonomic study revealed that the Western Central Pacific populations were a separate species and that L. temminckii was restricted to the northern Indian Ocean. In this study, the paucity of data available for the true L. temminckii was highlighted. Recently collected specimens of L. temminckii has allowed for a detailed redescription of this species from the northern Arabian Sea to complement the previous taxonomic work on this genus.

Notes on the Indian swellshark, Cephaloscyllium silasi (Scyliorhinidae: Carcharhiniformes) from deep waters off the west coast of India

The Indian swellshark Cephaloscyllium silasi is a poorly known deep water scyliorhinid (Carcharhiniformes) shark described from the south-west coast of India (off Kollam). Since the original description, reports of this species are absent due to rarity of specimens. This paper presents the first report of its egg case and also provides detailed morphological data about C. silasi based on recently collected materials.

First report of longfin escolar, Scombrolabrax heterolepis (Perciformes: Scombrolabracidae) from Indian waters

The taxonomy of deep-sea fishes of India was pioneered by the outstanding works of A.W. Alcock, based on the samples collected during the voyage of the Indian marine survey steamer, HMS ‘Investigator’. Alcock’s publications (1889–1907) are the major detailed work on the deep-sea fauna of Indian waters. Recent studies on deep-sea fishes from the Indian exclusive economic zone has resulted in the description of many new species and new records from Indian waters (Oommen, 1978; Sajeevan et al., 2009; Akhilesh et al., 2010; Bineesh et al., 2010; Kurup et al., 2010; Anderson & Bineesh, 2011).

Report of Apogonichthyoides sialis (Perciformes: Apogonidae) from the west coast of India

The cardinal fish, Apogonichthyoides sialis, previously known from the eastern Indian Ocean and western Pacific, is reported from the south-west coast of India (Kerala coast). The specimens are described and figured.

Redescription of Chlorophthalmus corniger, a senior synonym of Chlorophthalmus bicornis (Family: Chlorophthalmidae)

Chlorophthalmus corniger is redescribed on the basis of recently collected specimens. The species is redefined as a species of Chlorophthalmus with the lower jaw terminating in a distinctly projecting horizontal plate with strong, spine-like processes directed forward from the plates corners; body silvery grey, with numerous minute black spots and traces of broad darker crossbars; base of anterior dorsal fin spines and distal parts of dorsal fins black; adipose fin tiny with numerous black spots; caudal fin black; 3·5 scales above lateral line; three rows of cheek scales; head very large, 34·3-40·1% standard length (LS ); eye large, 29·8-40·8% head length (LH ); pectoral fin long, extending to beyond dorsal fin base, 21·7-26·2% LS . Chlorophthalmus bicornis is a junior synonym of C. corniger based on the examination of the type series of both species. It is confined to the northern half of the Indian Ocean, reliably recorded from Somalia and the Gulf of Aden to southern Java, Indonesia, at depths between 200 and 500 m. A lectotype and three paralectotypes were designated for C. corniger. DNA barcodes for Indian species of Chlorophthalmus were generated.