Lestidium Gilbert, 1905

Ho, Hsuan-Ching, Graham, Ken & Russell, Barry, 2020, Three new species of the barracudina genus Lestidium (Aulopiformes: Paralepididae) from the Indo-West Pacific, Zootaxa 4767 (1), pp. 71-88 : 72

Genus Lestidium Gilbert, 1905

Lestidium Gilbert, 1905:607 (Type species: Lestidium nudum Gilbert, 1905 )

Diagnosis. Body moderately long, not especially slender; luminescent duct in abdominal cavity unbranched, extending forward to below opercle or before anterior margin of eye; nostrils well before a vertical through posterior end of maxilla; lateral line complete or incomplete; no light organ at anterior margin of orbit; a small luminescent duct along lower margin of orbit or absent; ventral adipose fin well-developed along margin between anus and AFO; DFO at above same vertical at or behind VFO, if behind, always before midpoint of V–A; and anal-fin rays 26–34.

Remarks. Lestidium comprises a small group of species with five species previously recognized in the genus: L. atlanticum , L. bigelowi Graae, 1967 , L. nudum , L. orientale Ho et al., 2019 , and L. prolixum Harry, 1953 .

Of these species, L. atlanticum can be distinguished by having the luminescent duct extending beyond the pectoral girdle to before anterior margin of eye. It is also the only species that is reported to have a worldwide distribution. In this study, we recognize the population from southern Taiwan and northwestern Australia as a distinct species.

Another nominal species in the genus is Lestidium blanci Kartha, 1971 which was originally described from the Arabian Sea. Examination of a specimen (NTM S.13146-021) collected from northern Australia shows that it lacks the diagnostic luminescent duct in the abdominal cavity or a light organ around eye and is clearly a member of Lestidiops , a genus also in need of revision. All members of Lestidium have the DFO clearly before the midpoint of V–A, whereas Lestidiops blanci has its DFO well behind the midpoint of V–A, which is unique among paralepidid s. Moreover, the lateral line of L. blanci ends slightly behind the middle of the anal-fin base, also clearly different from the three new species described herein.