Robin's Ghostshark

discussion

Remarks: Hydrolagus erithacus is the largest known ghostshark to date, exceeding that of H. trolli in length. The species was thought to be similar to what is now known to be H. affinis in South African waters. Presently, it is known from several seamounts in the southeast Atlantic and southwest Indian oceans, but it may prove to be much wider ranging in the Southern Ocean. Conservation status: DD (2020).

An annotated checklist of the chondrichthyans of South Africa

materials_examined

South Africa voucher material: Holotype: SAIAB 200578. Paratypes (8): SAIAB 200579, SAM 34432, SAM 34434, SAM 34723, SAM 34724, SAM 35442, SAM 35446, SAM 35447. South African distribution: Known from the Southeast Atlantic and Southwest Indian oceans, including near Marion Island and Prince Edward Island within the South African exclusive economic zone.

An annotated checklist of the chondrichthyans of South Africa

description

Comparisons. Hydrolagus erithacus is the second largest Hydrolagus species described to date, and can clearly be differentiated from the small-bodied chimaerids in the genus (e. g. H. africanus, H. alberti, H. alphus, H. barbouri, H. colliei, H. macrophthalmus, H. mirabilis, and H. mitsukurii). Hydrolagus africanus occurs nearest in geographic proximity to H. erithacus, but does not overlap in distribution, and is a much smaller species ( 300 mm) (Walovich et al. 2015). The anterior second dorsal fin height of H. africanus is taller (4 – 8 % vs. 3 - 5 % BDL) and the second dorsal height taller across its entire length (2 – 7 % vs. 3 – 5 % BDL D 2 PH, 1 – 6 % vs. 3 – 5 % BDL D 2 MH). The coloration of fresh H. africanus is silver and brown and when preserved turns a uniform light brown. Additionally, the uniform black color of H. erithacus separates it from the patterned species such as H. alphus, H. colliei, H. marmoratus, H. mccoskeri, and H. novaezealandiae. The seven species most similar to H. erithacus in color and body size are compared. Three species of these large bodied Hydrolagus are known only to occur in the North Atlantic, H. affinis, H. pallidus and H. lusitanicus (Eb

Hydrolagus erithacus sp. nov. (Chimaeriformes: Chimaeridae), a new species of chimaerid from the southeastern Atlantic and southwestern Indian oceans

description

Description. Morphometric measurements of the holotype are given followed in parenthesis by a range of eight paratypes and are presented in Table 1. Large bodied species (1169 – 1442 mm TL, 765 – 945 mm BDL) with bulky head 28 % (27 – 31 %) BDL and pointed snout 15 % (15 – 18 % POB) BDL (Figure 2). Body depth uniform from insertion of pectoral fins to insertion of pelvic fins. Pectoral-pelvic space 35 % (29 – 36 %) BDL, approximately twothirds (54 – 71 %) BDL the pelvic-caudal space 51 % (46 – 61 %) BDL. Snout-to-vent length 70 % (62 – 69 %) BDL, longer than pelvic-caudal space 51 % (46 – 61 %) BDL. Eyes oval along horizontal axis, length 6 % (5 – 7 %) BDL, 17 % (18 – 22 %) HDL and height 4 % (3 – 5 %) BDL, 15 % (12 – 17 %) HDL. Skin firm, not deciduous. Holotype Paratypes (n = 8) mm % BDL mm % BDL TL 1290 163 1169 – 1442 151 – 159 PCL 1025 130 935 – 1210 121 – 132 SVL 550 70 483 – 635 62 – 69 BDL 790 - 765 – 945 - TRL 320 41 275 – 383 35 – 44 HDL 225 28 219.9 – 282 27 – 31 PD 1 225 28 245 – 295 28 – 35 PD 2 419 53 431 – 515 53 – 57 PP 1 245 31 231 – 380 29 – 42 PP 2 575 73 531 – 655 69 – 75 POB 120 15 113.5 – 163.4 15 – 18 PRN 85 11 32.5 – 105 4 – 12 POR 109 14 46.5 – 130 5 – 15 S

Hydrolagus erithacus sp. nov. (Chimaeriformes: Chimaeridae), a new species of chimaerid from the southeastern Atlantic and southwestern Indian oceans