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| Caecognathia tubicola Ota & Yoshimatsu, 2025 |
Abstract
Two gnathiid species were collected from around Kagawa Prefecture, Seto Inland Sea, western Japan. One species was described as Caecognathia tubicola sp. nov. with detailed morphological examinations of male and female adults and larvae. A total of 130 individuals of C. tubicola were obtained from empty tubes of the polychaetous annelid Spirobranchus akitsushima in the intertidal zone. This species probably completes its life cycle around the aggregation of empty calcareous tubes of S. akitsushima on bedrock, as larvae at all developmental stages were found. Some adult females have significantly narrow thoraxes, a morphology that may be adapted to the elongate tubes. Small numbers of Elaphognathia cornigera (Nunomura, 1992) were also found in empty S. akitsushima tubes.
Keywords: Caecognathia, ectoparasite, intertidal zone, narrow thorax
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| Caecognathia tubicola sp. nov. Habitat of at Mitoyoshi City, Kagawa Prefecture. A, intertidal rocky shore with mats of aggregations of tube of polychaete worm Spirobranchus akitsushima; B, mouth of empty tubes of S. akitsushima; C, male adult of C. tubicola in a tube. Live specimens (D-F) |
Family Gnathiidae Leach, 1814
Genus Caecognathia Dollfus, 1901
Caecognathia tubicola sp. nov.
[Japanese name: Kanzashi-umi-kuwagata]
Diagnosis. Dorsal surface of cephalosome, pereonites 1–3, and anterior part of pereonite 4 densely covered with fine granules; frontal border rounded, slightly dentate, fringed with fine setae; paraocular ornamentation multiple projections, covering part of eyes in dorsal view; pereonite 1 not fused with cephalon and divided into 3 parts; epimera not prominent on pleonites 1–5; pleotelson covered with pectinate scales on anterior half and fine spines on posterior part.
Yuzo Ota and Sadaaki Yoshimatsu. 2025. Two gnathiid isopods utilizing empty tubes of the polychaete worm Spirobranchus akitsushima in the Seto Inland Sea, western Japan, with the description of a new species. Plankton and Benthos Research. 20(4); 248-262. DOI: doi.org/10.3800/pbr.20.248
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