Ovicides paralithodis (Nemertea, Carcinonemertidae), a new species of symbiotic egg predator of the red king crab Paralithodes camtschaticus (Tilesius, 1815) (Decapoda, Anomura).

Hiroshi Kajihara,Armand M Kuris

doi:10.3897/zookeys.258.4260

Hiroshi Kajihara, Armand M Kuris

Open Access

https://doi.org/10.3897/zookeys.258.4260

Copy DOI

Journal: ZooKeys	Publication Date: Jan 14, 2013
Citations: 7	License type: CC BY 3.0

Affiliation: Hokkaido University, California Coast University

Abstract

Ovicides paralithodis sp. n. is described from the egg mass of the red king crab Paralithodes camtschaticus (Tilesius, 1815) from the Sea of Okhotsk, off Hokkaido, Japan, and Alaska, USA. Among four congeners, Ovicides paralithodis can be distinguished from Ovicides julieae Shields, 2001 and Ovicides davidi Shields and Segonzac, 2007 by having no eyes; from Ovicides jonesi Shields and Segonzac, 2007 by the presence of basophilic, vacuolated glandular lobes in the precerebral region; and from Ovicides jasoni Shields and Segonzac, 2007 by the arrangement of the acidophilic submuscular glands, which are not arranged in a row. Ovicides paralithodis represents the third described species of egg-predatory nemertean from Paralithodes camtschaticus, the second described carcinonemertid species from Japan, and the 21st described species in the family. The intensity of infestations may exceed 24,000 worms per a single egg-bearing pleopod of Paralithodes camtschaticus. A preliminary molecular phylogenetic analysis based on sequences of 28S rRNA and cytochrome c oxidase subunit I genes among selected monostiliferous hoplonemertean species supported the monophyly of Carcinonemertidae, suggesting that within the lineage of the family, evolution of the unique vas deferens, Takakura’s duct, preceded loss of accessory stylets and accessory-stylet pouches.

Highlights

Nemerteans in the monostiliferous hoplonemertean family Carcinonemertidae are ectosymbiont egg predators of decapod crustacean hosts (Humes 1942, Jensen and Sadeghian 2005)
One may infer from the present tree topology that the acquisition of Takakura’s duct and the loss of cerebral organs occurred in the common ancestor of the family, prior to the loss of accessory stylet pouches or stylets, which happened only in the lineage leading to Carcinonemertes, but not in Ovicides
We conclude so because 1) Takakura’s duct is possessed by all carcinonemertids, and is otherwise unique in the phylum, 2) with a few exceptions, monostiliferans generally possess cerebral organs, and 3) accessory stylets and their pouches are widespread features among Hoplonemertea, including Ovicides, but are absent in Carcinonemertes. An implication of this character-evolution scenario is that the genus Ovicides, currently diagnosed as a nemertean egg predator having accessory stylets, may not be monophyletic

Summary

Introduction

Nemerteans in the monostiliferous hoplonemertean family Carcinonemertidae are ectosymbiont egg predators of decapod crustacean hosts (Humes 1942, Jensen and Sadeghian 2005). The family is comprised of two genera, Carcinonemertes Coe, 1902 and Ovicides Shields, 2001, each containing 16 (Sadeghian and Santos 2010) and four (Shields and Segonzac 2007) species, respectively. They are known from approximately 70 host species (Sadeghian and Santos 2010), but the actual diversity of carcinonemertids is likely to be much greater (Kuris 1993). Forms 1 and 2 sensu Wickham and Kuris (1988) were respectively described as C. regicides Shields, Wickham and Kuris, 1989 and A. oclairi, while Forms 3–5 remained undescribed

Methods

Results

Conclusion