The Cape lobster, Homarinus capensis, is a species of small lobster that lives off the coast of South Africa, from Dassen Island to Haga Haga. Only a few dozen specimens are known, mostly regurgitated by reef-dwelling fish. It lives in rocky reefs, and is thought to lay large eggs that have a short larval phase, or that hatch directly as a juvenile. The species grows to a total length of 10 cm (3.9 in), and resembles a small European or American lobster; it was previously included in the same genus, Homarus, although it is not very closely related to those species, and is now considered to form a separate, monotypic genus – Homarinus. Its closest relatives are the genera Thymops and Thymopides.
Extreme points of the range of Homarinus capensis in South Africa
The Cape lobster is endemic to South Africa. It occurs from Dassen Island, Western Cape in the west to Haga Haga, Eastern Cape in the east, a range of 900 kilometres (560 mi).[5] Most of the known specimens were regurgitated by fish caught on reefs at depths of 20–40 metres (66–131 ft).[5] This suggests that the Cape lobster inhabits rocky substrates, and may explain its apparent rarity, since such areas are not amenable to dredging or trawling, and the species may be too small to be retained by lobster traps.[5]
Description
Homarinus capensis is considerably smaller than the large northern lobsters of the Atlantic Ocean, Homarus gammarus (the European lobster) and Homarus americanus (the American lobster), at 8–10 centimetres (3.1–3.9 in) total length, or 4–5 cm (1.6–2.0 in) carapace length.[4][6] Accounts of the colouration of H. capensis are very variable, from tawny, red or yellow to "a rather dark olive", similar to Homarus gammarus.[7]
Homarinus and Homarus are considered to be the most plesiomorphic genera in the family Nephropidae.[8] Nonetheless, the Cape lobster differs from Homarus in a number of characters. The rostrum of the Cape lobster is flattened, while that of Homarus is rounded in section, and curves upwards at the tip.[5] The three pairs of claws[Note 1] are covered with hairs in Homarinus, while those of Homarus are hairless.[4] The telson tapers along its length in Homarus, but has sides which are nearly parallel in Homarinus.[5] Although no egg-bearing females have been collected, the gonopores (openings of the oviducts) of female Cape lobsters are much larger than those of Homarus gammarus and Homarus americanus.[5] This is thought to indicate that Homarinus bears fewer, larger eggs than Homarus, and that either the larvae develop quickly into juveniles after hatching, or that the eggs hatch directly into juveniles.[5][10]
The Cape lobster was first described by Johann Friedrich Wilhelm Herbst in 1792 as Cancer (Astacus) capensis.[9][11] It was independently described in 1793 by Johan Christian Fabricius as Astacus flavus, possibly based on the same type specimen.[9] When Friedrich Weber erected the genus Homarus in 1795, he included Fabricius' species in it, but this placement was not followed by later authors.[9] The species reached its current classification in 1995, when the monotypic genus Homarinus was erected by Irv Kornfield, Austin B. Williams and Robert S. Steneck.[7]
^ abcdefghRyusuke Kado; Jiro Kittaka; Yasuhiro Hayakawa & D. E. Pollock (1994). "Recent discoveries of the "rare" species Homarus capensis (Herbst, 1792) on the South African coast". Crustaceana. 67 (1): 71–75. doi:10.1163/156854094x00305. JSTOR20104967.
^ abcdDale Tshudy; Rafael Robles; Tin-Yam Chan; Ka Chai Ho; Ka Hou Chu; Shane T. Ahyong; Darryl L. Felder (2009). "Phylogeny of marine clawed lobster families Nephropidae Dana, 1852, and Thaumastochelidae Bate, 1888, based on mitochondrial genes". In Joel W. Martin; Keith A. Crandall; Darryl L. Felder (eds.). Decapod Crustacean Phylogenetics. CRC Press. pp. 357–368. doi:10.1201/9781420092592-c18. ISBN978-1-4200-9258-5.