Traditional and confocal descriptions of a new genus and two new species of deep water Cerviniinae Sars, 1903 from the Southern Atlantic and the Norwegian Sea: with a discussion on the use of digital media in taxonomy (Copepoda, Harpacticoida, Aegisthidae)

Abstract

Aegisthidae is one of the most abundant and diverse families of harpacticoid copepods living in deep-sea benthos, and the phylogenetic relationships within the family are in state of flux. Females of two new deep-water species of harpacticoid copepods belonging to the Hase gen. n. (Aegisthidae: Cerviniinae) are described. The first taxonomic description of marine copepod species based on the combined use of interference and confocal microscopy for the study of the habitus and dissected appendages is presented here. CLSM (Confocal Laser Scanning Microscopy) is a non-destructive method, comparable in quality to SEM (scanning electron microscopy) at the same magnifications. To observe and reconstruct in detail the habitus and dissected appendages, whole specimens and dissected parts were stained with Congo Red, mounted on slides with glycerine for CLSM and scanned under three visible-light lasers. Hase lagomorphicus gen. et sp. n. and Hase talpamorphicus gen. et sp. n. were collected from the sediments of the Southern Atlantic and the Norwegian Sea, from 2270 m and 5468 m depths, respectively. Hase gen. n. is included within Cerviniinae based on the caudal rami which are relatively divergent. Hase gen. n. is the sister taxon of Cerviniella based on the following synapomorphies: sturdy body, exopodites 1–3 of pereopods 1–3 heavily built, transformed into digging limbs, with strong outer and distal spines/setae, two-segmented endopod on the pereopods 2 and 3, and a reduced pereopod 5. Compared to Cerviniella, Hase gen. n. exhibits a more developed armature on the pereopod 1, which has outer and distal elements transformed into strong and long spines vs. stiff setae on Cerviniella.Hase gen. n. has one or two strong and long spines on the inner margin of the exopodite 3 of pereopod 4 and pereopod 5 is fused to the somite, ornamented with three distal setae. The telson of Hase gen. n. is subquadratic, and the furca is among the shortest yet described for Aegisthidae. The new species differ in a number of diagnostic characters, three of which are: a) the somite bearing pereopods 3 and 4 with latero-distal spiniform processes in H. talpamorphicus gen. et sp. n. but smooth in H. lagomorphicus gen. et sp. n., b) antenna is armed with three stout spines on the lateral inner margin of the exopod in H. talpamorphicus gen. et sp. n. and two proximal setae in H. lagomorphicus gen. et sp. n., and c) pereopod 4 exopodite 3 has two long and strong spines on the inner margin in H. lagomorphicus gen. et sp. n. and one spine in H. talpamorphicus gen. et sp. n. The high quality of CLSM images should foster discussion about the use of high quality digital images as type or as part of the type series in zoological studies, especially when studying rare and small macrofaunal and meiofaunal taxa.

Genus level molecular phylogeny of Aegisthidae Gisbrecht, 1893 (Copepoda: Harpacticoida) reveals morphological adaptations to deep-sea and plagic habitats

“…Our molecular analysis confirms the sister relationship between Aegisthinae and here re-defined Pontostratiotinae (which includes members of the Pontostratiotes only) and rejects the monophyly of the former Pontostratiotinae. [24] In this study, the analyzed genera belonging to the Aegisthinae (Aegisthus, Andromastax, Nudivorax, and Jamstecia) have a complex topology (Fig. 1) in which there is no evidence supporting the monophyly of none of the four genera.…”

Five new coexisting species of copepod crustaceans of the genus Spaniomolgus (Poecilostomatoida: Rhynchomolgidae), symbionts of the stony coral Stylophora pistillata (Scleractinia)

“…For confocal microscopy, exoskeletons were individually transferred to distilled water and then stained with Fuchsin (Ivanenko et al 2012; Corgosinho et al 2018). The copepods were inspected using an inverted Nikon A1 confocal laser scanning microscope (CLSM, Nikon Corporation, Tokyo, Japan) at Lomonosov Moscow State University, using a 40× oil immersion objective and lasers with wavelengths of 532 and 640 nm.…”