New species of the genus Mesocletodes Sars, 1909 from the deep Gulf of California (Copepoda, Harpacticoida).

Samuel Gómez

doi:10.3897/zookeys.751.20387

Abstract

Investigations on the effects of the oxygen minimum zone on the distribution, abundance, and diversity of deep-sea benthic and pelagic fauna of the Gulf of California and Eastern Tropical Pacific has received attention recently. However, very little is known about the diversity of deep-sea benthic harpacticoids from this region, and only three species, Ancorabolus hendrickxi Gómez & Conroy-Dalton, 2002, Ceratonotus elongatus Gómez & Díaz, 2017 and Dendropsyllus californiensis Gómez & Díaz, 2017, have been described so far. The genus Mesocletodes Sars, 1909 is one of the most common and abundant genera of deep-sea harpacticoids. This genus has been traditionally subdivided into two species groups, the abyssicola and the inermis groups, based on the presence/absence of a dorsal cuticular process on the cephalothorax and anal somite, but some species have been reported to deviate from this scheme. As a result of their investigations, other researchers proposed the monophyly of the abyssicola group, and suggested the probable monophyly of two other species-groups. In this paper, the descriptions of three new species of the genus Mesocletodes from the deep sea of the Gulf of California are presented with some notes on their relationships with other species. Some comments on the monophyly of the genus are given.

Highlights

Great effort has been deployed since the late 1980’s to study the biodiversity of the deep sea of the Gulf of California and Eastern Tropical Pacific
Menzel and George (2009) did not follow Bodin’s (1968, 1997) and Por’s (1986) views. They suggested the monophyly of the abyssicola group based on the elongation of the caudal rami, and on the presence of a dorsal process on the cephalothorax and on the anal somite, and pooled all the species of Mesocletodes, with a dorsal cuticular process either on the cephalothorax or on the anal somite, or both, and with long or short caudal rami, in the abyssicola group, arguing that the deviation of Bodin’s (1968, 1997) scheme, and the shorter caudal rami observed in some species could eventually be regarded as secondary reductions (Menzel and George 2009: 253)
Scott & A Scott, 1901), and recognized the relationship between the latter two species. He noted the lack of dorsal processes on the cephalothorax and anal somite of M. inermis, but omitted any comment on the relationship of this species and M. irrasus

Summary

Introduction

Great effort has been deployed since the late 1980’s to study the biodiversity of the deep sea of the Gulf of California and Eastern Tropical Pacific (a complete list of contributions is available upon request). Menzel and George (2009) did not follow Bodin’s (1968, 1997) and Por’s (1986) views Instead, they suggested the monophyly of the abyssicola group based on the elongation of the caudal rami, and on the presence of a dorsal process on the cephalothorax and on the anal somite, and pooled all the species of Mesocletodes, with a dorsal cuticular process either on the cephalothorax or on the anal somite, or both, and with long or short caudal rami, in the abyssicola group, arguing that the deviation of Bodin’s (1968, 1997) scheme (presence of a dorsal process on the cephalothorax or on the anal somite only), and the shorter caudal rami observed in some species could eventually be regarded as secondary reductions (Menzel and George 2009: 253). Some comments on the monophyly of Mesocletodes are provided

Materials and methods

Discussion