Hymenocephalus heterolepis ( Alcock, 1889 )

Schwarzhans, Werner, 2014, Head and otolith morphology of the genera Hymenocephalus, Hymenogadus and Spicomacrurus (Macrouridae), with the description of three new species, Zootaxa 3888 (1), pp. 1-73 : 50-52

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https://doi.org/10.11646/zootaxa.3888.1.1

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scientific name

Hymenocephalus heterolepis ( Alcock, 1889 )
status

 

Hymenocephalus heterolepis ( Alcock, 1889) View in CoL

Figs. 24A–M View FIGURE 24 , 27 View FIGURE 27

Macrurus heterolepis Alcock 1889: 396 View in CoL (syntypes from: Andaman Sea, off Ross Island, and Bay of Bengal , between North and South Sentinel Islands).

Macrurus (Mystaconurus) heterolepis: Alcock 1891: 122 View in CoL and 309 (figure).

Macrurus (Mystaconurus) cavernosus: Alcock 1899: 117 View in CoL (records from Andaman Sea only).

Hymenocephalus heterolepis: Iwamoto View in CoL in Cohen et al. 1990: 231.

Material examined. 114 specimens; 1 specimen BMNH 1890.7 .31.6 (syntype), about 120 mm TL, Andaman Sea , off Ross Island ; 98 specimens CAS 50132, 83 About CAS + – 121 mm TL, 10°39’N, 96°34’E, 367–375 m GoogleMaps ; 15 specimens CAS 50124, 91 About CAS + –120+ mm TL, 10°39’N, 97°06’E, 293 m GoogleMaps .

Diagnosis. Pelvic fin rays 10–11; pectoral 11–13; gill rakers 22–25. Barbel short, 5–10% HL, not reaching vertical through anterior rim of orbit. Orbit 28–32% HL. Snout pointed, protruding, 17.5–20% HL. Ventral striae extending to about ⅔ the distance from pelvic fin bases to periproct ( Fig. 24F View FIGURE 24 ). Otolith compressed, OL:OH = 0.9–0.95; colliculi separated, small, narrowly placed across collum; pseudocolliculum long, TCL:PCL = 1.5–1.7.

Comparison. Hymenocephalus heterolepis resembles H. italicus , with which it commonly has been synonymized (first synonymized with H. cavernosus by Alcock (1899), see below under H. italicus ) and the new species H. punt described in the following. From H. italicus it differs in the smaller orbit (28–33 % HL vs 35–40% HL) and the separated colliculi of the otolith (vs joined). The additional distinguishing character of the otoliths supports the recognition of the species. For distinction from H. punt n.sp. see below.

Description. Head morphology (n = 4) ( Fig. 24A–E View FIGURE 24 ): Snout moderately long, pointed, projecting, 17.5–20% HL, orbit diameter small, 28–32% HL, interorbital width 60–65% HW. Barbel short, 5–10% HL, not reaching vertical through anterior rim of orbit. Head canals well developed, infraorbital width 12–16% HL, supraorbital canal with 5 to 6 segments, width 12–15% HL, supratemporal canal rarely observable, above segment 4 of supraorbital canal, preopercular canal width 13–15% HL, postorbital-preopercular interspace 6–8% HL. Infranasal supporter moderately large; infraorbital supporter short, expanding only beyond rear part of orbit, 35–70% OD; preopercular supporter moderately long, 6–8% HL, with straight rear margin.

Otolith morphology (n = 7) ( Fig. 24H–M View FIGURE 24 ): Otolith large; OL:OH = 0.9–0.95; OH:OT = 3.2–3.5. Dorsal rim with large, very broad, somewhat crenulated predorsal lobe with mostly pointed tip, distally inclining to posterior tip without marked incision; posterior tip at about level of sulcus termination; ventral rim deep, regularly curved, smooth, deepest anterior of the middle; anterior rim high, subvertical to nearly vertical. Inner face slightly convex, with median sulcus. Ostial and caudal colliculi small, narrowly placed across collum, terminating far from anterior and posterior tips of otolith; pseudocolliculum long. CCL:OCL = 0.9–1.3; TCL:PCL = 1.5–1.7. Dorsal depression moderately large, indistinct; ventral furrow distinct, moderately close to ventral rim.

Discussion. Alcock (1899) stated that he was ”satisfied by actual comparison of the specimens with one received from the Smithsonian Institution, that the species described by him as Mystaconurus heterolepis is the same as Goode and Bean’s Hymenocephalus cavernosus ”, and he believed ”that both these names will prove to be synonyms of Giglioli’s Hymenocephalus italicus from the Mediterranean”. After analysis of the specimens available to me, and in particular after investigation of the size of the orbit and the morphology of the otoliths, I conclude that H. heterolepis should be recognized as a valid species, in line with the recommendation made by Iwamoto (in Cohen et al., 1990).

Distribution ( Fig. 27 View FIGURE 27 ). Hymenocephalus heterolepis appears to be geographically restricted to the sea around the Andaman Islands and the western coast of the Malay Peninsula.

Alcock, A. (1889) Natural history notes from H. M. Indian Marine Survey Streamer ' Investigator', Commander Alfred Carpenter, R. N., D. S. O., commanding No. 13. On the bathybial fishes of the Bay of Bengal and neighboring waters, obtained during the seasons 1885 - 1889. Annals and Magazine of Natural History, Series 6, 4, 376 - 399. http: // dx. doi. org / 10.1080 / 00222938909460547

Alcock, A. (1891) On the deep-sea fishes collected by the ' Investigator' in 1890 - 1891. Annals and Magazine of Natural History, Series 6, 8, 119 - 138. http: // dx. doi. org / 10.1080 / 00222939109460407

Alcock, A. (1899) A Descriptive Catalogue of the Indian Deep-Sea Fishes in the Indian Museum. Indian Museum, Calcutta, 211 pp. http: // dx. doi. org / 10.5962 / bhl. title. 4684

Cohen, D. M., Inada, T., Iwamoto, T. & Scialabba, N. (1990) FAO species catalogue Vol. 10. Gadiform fishes of the world (Order Gadiformes). FAO Fisheries Synopsis, 125 (10), 442 pp. [Rome]

Gallery Image

FIGURE 24. Hymenocephalus heterolepis: A—CAS 50132, TL 93+ mm, lateral view of head. B–C—CAS 50132, TL 85+ mm, B—Lateral view of head, C—Dorsal view of head. D–E—Syntype, BMNH 1890.7.31.6, D—Lateral view of head, E—Dorsal view of head. F–G—CAS 50132, TL 85+ mm, F—Ventral view of head and trunk, G—detail view of posterior lens of ventral luminescent organ. H–M—Otoliths, CAS 50132, H—Anterior view, I, K–M—Inner faces, J—Ventral view.

Gallery Image

FIGURE 27. Geographical distribution of Hymenocephalus antraeus, H. hachijoensis, H. heterolepis and H. punt.

CAS

California Academy of Sciences

Kingdom

Animalia

Phylum

Chordata

Class

Actinopterygii

Order

Gadiformes

Family

Macrouridae

Genus

Hymenocephalus