Leptochiton belknapi Dall, 1878

Sirenko, Boris, 2015, Shallow and deep-sea chitons of the genus Leptochiton Gray, 1847 (Mollusca: Polyplacophora: Lepidopleurida) from Peruvian and Chilean waters, Zootaxa 4033 (2), pp. 151-202 : 154

Leptochiton belknapi Dall, 1878

Leptochiton belknapi Dall 1878: 1 ; Kaas & Van Belle 1987: 23, fig.10; Schwabe & Sellanes 2010: 33, fig.1L–M

Leptochiton alveolus ; Ferreira 1979:152, fig 10 (in part, non Chiton alveolus M.Sars MS, Lovén, 1846); Kaas & Van Belle 1985: 36, fig.14, map 6, (in part, non Chiton alveolus Lovén, 1846 ).

Leptochiton farallonis Dall 1902: 557 .

Leptochiton mesogonus Dall 1902: 555 .

Leptochiton opacus Dall 1908: 218 .

Leptochiton sp. Sellanes et al. 2004: 1066.

Type. Holotype ( USNM 30972).

Type locality. off Western Aleutian Islands, 53°08’N, 171°19’W, 1840 m depth.

Material examined. Holotype of L. belknapi ( USNM 30972), L. alveolus [(2 spms from the Norwegian Sea, 2 spms from Newfoundland Bank, 1 spm from off Vineyard ( USNM 602353)], two syntypes of L. giganteus ( ZMA); holotype L. halistreptus ( USNM 10932); syntypes of L. halistreptus abbreviatus ( USNM 223498); syntype of L. opacus ( USNM 110664); lectotype L. japonicus ( ZMHU 102038); holotype of L. luridus ( USNM 109027), holotype of L. farallonis ( USNM 109025) and holotype of L. mesogonus ( USNM 109019)].

Peruvian and Chilean record. Sellanes et al. 2004, (as Leptochiton sp.) and Schwabe & Sellanes 2010 (from off Peru, 11°50’S to off Chile, 42°40’S).

Distribution. Wide spread species, inhabits the Pacific Ocean from the Sea of Okhotsk and Bering Sea to North and South America’s Pacific waters southwards to 42°40’S, 200–1840 m.

Remarks. Studied material showed that several species which were synonymized with L. belknapi by Kaas & Van Belle (1987) are valid. Among them are Leptochiton luridus , L. halistreptus halistreptus , L. halistreptus abbreviatus , L. giganteus , L. japonicus . Leptochiton luridus differs from L. belknapi by having three cusps in major lateral teeth of radula and dorsal scales without ribs. Leptochiton luridus belongs to the L. vitjazi group. Both subspecies of L. halistreptus halistreptus and L. halistreptus abbreviatus differ from L. belknapi by having extensive rows of gills arranged from anus to valve V and by having the tail valve wider than the head valve. Leptochiton giganteus differs from L. belknapi by having the width of the jugal sinus almost equal to the width of the apophyses (width of jugal sinus much wider than apophyses in L. belknapi ), dorsal scales without ribs. Leptochiton japonicus differs from L. belknapi in having 7 instead of 3 pores in the granules and 6–8 instead of 3 ribs in dorsal scales. According to Saito (1997), L. japonicus and L. aequispinus are valid species. In my opinion, L. simplex is a synonym of L. japonicus because L. simplex has 6 ribs on the dorsal scales of the girdle and similar valves. Other species (see Kaas & Van Belle 1987) were left in the synonymy of L. belknapi . I think that some specimens from Peruvian and Chilean samples recorded by Sellanes et al. (2004) as Leptochiton sp. and by Schwabe & Sellanes (2010) as L. belknapi may belong to one of the new deep-water species, described in this article from the Peru-Chile Trench ( Leptochiton sigwartae , L. mutschkeae and L. macleani ). Further work beyond the scope of this paper is necessary to study the specimens by Scanning Electron Microscope.