The redescription of three species of Sicyonella (Crustacea: Decapoda: Dendrobranchiata: Sergestidae)

Abstract

Three species of Sicyonella, S. antennata, S. inermis, and S. maldivensis, were redescribed and illustrated in detail. In addition to characters of the antennular peduncle and petasma, the three species are distinguished by the shape and armature of the proximal part of the mesial antennular flagellum of the male, the color of the antennal flagellum, the number and size of spiniform setae on the distomesial corner of the sympod of the second, third, and fifth pleopods, and the shape of the thelycum. On the basis of these characters, a female of the syntype of S. maldivensis from Mauritius was identified as S. inermis. Therefore, a male of the syntype from the Maldives is designated the lectotype of S. maldivensis.

Global Diversity and Phylogeny of Pelagic Shrimps of the Former Genera Sergestes and Sergia (Crustacea, Dendrobranchiata, Sergestidae), with Definition of Eight New Genera

“…It is common opinion (to be tested phylogenetically) that pereopods have been gradually reduced within Sergestidae possibly as an adaption to a pelagic life style. Sicyonella antennata (outgroup), which occurs in near-bottom water layers [23] – [24] where many groups of shrimps are known to have evolved [25] , has, with other species in the genus, the least reduced pereopods within the family, e.g., with chelae on pereopod 1 and dactyli on pereopods 4 and 5. Species of this genus also have well-developed gills (branchiae) and no luminous organs.…”

Phylogeny and taxonomy of the enigmatic genusPetalidium(Decapoda, Sergestidae), with biological remarks

“…The family comprises: (1) seventy‐one species of the former genus Sergestes sensu H.J.H. Hansen (, ), now split into fifteen genera (Vereshchaka, Olesen & Lunina, ); (2) fourteen species of Acetes (Omori, ); (3) three species of Petalidium (Hansen, , ; Burkenroad, ); (4) three species of Sicyonella (Hansen, ; Fukuoka, Tamaki & Kikuchi, ); and (5) one species of Peisos (Burkenroad, ).…”

“…The taxonomy of Sergestidae had become entangled until recently, for historical and other reasons (Vereshchaka, , , ) but has now been more or less disentangled in a series of revisions that include diagnoses and redescriptions of most genera and species. In chronological order, these revisions are: Acetes (Omori, ), Sergia (Vereshchaka, ; Vereshchaka et al ., ), Sicyonella (Fukuoka et al ., ), and Sergestes (Vereshchaka, ; Vereshchaka et al ., ). Only the deep‐sea genus Petalidium remains unrevised.…”