First use of molecular evidence to match sexes in the Monstrilloida (Crustacea: Copepoda), and taxonomic implications of the newly recognized and described, partlyMaemonstrilla-like females ofMonstrillopsis longilobataLee, Kim & Chang, 2016

Abstract

Two forms of the monstrilloid copepod, one represented by males, the other by females, were dominant among the monstrilloids collected while sampling zooplankton with a light trap in southern coastal waters of Korea. Morphological examination revealed that the males are conspecific with the previously reported and rather specialized Korean species Monstrillopsis longilobata Lee, Kim & Chang, 2016, hitherto known only from males that have extremely long genital lappets. The females also show several diagnostic features of Monstrillopsis, such as prominent eyes, bilobed fifth legs with the inner lobe unarmed and reduced, and four urosomal somites. In addition, though, these females are extraordinary among all Monstrilloida in that their ovigerous spines are directed ventrally, not posteriorly as in most species or anteriorly as in those assigned to Maemonstrilla. Genetic divergence analyses based on partial mitochondrial cytochrome c oxidase subunit I, complete Internal Transcribed Spacer 1 (ITS1)–5.8S–ITS2, and partial 28S rRNA revealed little or no genetic divergence between the present males and females, thus demonstrating that they are mutually conspecific. The present report (1) provides the first morphological description of female M. longilobata with the proposal of a revised nomenclature for antennular setal armament; (2) presents the molecular evidence for conspecificity of the males and females; and (3) lists several morphological characteristics that are sexually dimorphic in this species, and thus likely also in other monstrilloids. Matters bearing on the validity of the genera Haemocera, Monstrillopsis, and Maemonstrilla are discussed.

New species of Caromiobenella Jeon, Lee & Soh, 2018 (Crustacea, Copepoda, Monstrilloida) from Chuja Island, Korea

“…Caromiobenellahamatapex is known only from the female; thus, direct comparison with the present male specimens is risky due to the occurrence of strong sexual dimorphism in the order Monstrilloida (Suárez-Morales 2007; Suárez-Morales et al 2008; Jeon et al 2018b).…”

“… Caromiobenellaohtsukai sp. n., male holotype (MABIK CR00244260), antennule labelling following Jeon et al (2018b) A Left antennule, dorsal, last segment slightly upward (cf. Fig.…”

“…Length of each body somite was measured along dorsal medial line from the anterior end to the posterior end, and total body length was represented by a sum of those measurements. Terminology from Grygier and Ohtsuka (2008) and Jeon et al (2018b) was used to describe body segmentation and antennular setation patterns, respectively. For caudal setae numbering, definitions from Huys and Boxshall (1991) were adopted over those of Huys et al (2007) in consideration of the seemingly dorsal position of the VII seta.…”

“…Thermal cycling was performed using Mastercycler (Eppendorf, Hamburg, Germany) or MyGenie 96 Thermal Block (Bioneer). For mtCOI gene amplification, XcoiF (5’-ATAACRCTGTAGTAACTKCTCAYGC-3’; Jeon et al 2018b) and HCO2198 (5’-TAAACTTCAGGGTGACCAAAAAATCA-3’; Folmer et al 1994) primers were used. The thermal cycling profile was 5 min at 94 °C for initial denaturation followed by 40 sec at 94 °C for denaturation, 45 sec at 50 °C for annealing, and 45 sec at 72 °C for elongation.…”

Extreme secondary sexual dimorphism in the genus Florarctus (Heterotardigrada: Halechiniscidae)

“…Karanovic 2008). Only molecular data could most objectively test the assertion of their conspecificity, analogously to actions undertaken by crustacean specialists in the copepod order Monstrilloida (Jeon et al 2018) to link sexes of one species. As a consequence, new marine heterotardigrades with strongly sexually dimorphic traits should not be described based on individuals of one sex, if only to avoid future synonymies.…”