Caphyra pectenicola Adams, 1847

Low, Martyn E. Y., Ng, Peter K. L. & Clark, Paul F., 2020, Additional notes on the publication of the Narrative, Zoology and Notes from a Journal of Research into the Natural History of the Voyage of H. M. S. Samarang and its consequences for the nomenclature of decapod crustaceans and other taxa, Zootaxa 4809 (2), pp. 271-305 : 292-293

Caphyra pectenicola Adams, 1847 and Caphyra pectenicola White, 1847 , identified with Conchoecetes artificiosus ( Fabricius, 1798) ( Decapoda : Brachyura : Dromiidae )

White (1847a: 54) listed “ Caphyra Guerin. Caphyra pectenicola , n.s. a. Philippine Islands. From Mr. Cuming’s collection”. Adams (1847c: 315) describes how “[m]any of the specimens both of Dorippe and of Dromia which I examined in this condition, had perfectly soft carapaces, and this body may serve them as a protection during the season of their moulting[.] The Caphyra pectenicola (White) bears a small pecten shell, in a similar manner. This curious little Crustacean, which was dredged by us in the Sunda Straits from thirteen fathoms, takes up its abode in the deepest valve of the deserted Pecten , locking itself on by the claws of its posterior legs to the ears of the shell, its tender back being secured from harm by this adventitious covering”. This part of the Natural History by Adam (1847c) deals with the “Sooloo” (= Sulu) area in the Philippines, which matches the locality given by White (1847a: 54).

Wood (1867: 225, unnumbered fig.) under the caption of “SCALLOP CRAB.— Caphýra pectenícola ” included a drawing of “[…] a small scallop shell, with a very little crab lying inside it. This is the Scallop Crab, so called on account of its habits. The general shape of this crab is not unlike that of the pea-crab […]”.

Under their entry for “Scallop”, Hunter & Morris (1898: 4126), lists: “scallop-crab […] Zool.: Caphyra pectenicola . It is closely akin to the Pea-crab […]”.

What is Caphyra pectenicola White (1847a) and Adams (1847c)? The name seems to have been forgotten and not used since 1898. Although the name in White (1847a) is a nomen nudum, Adams (1847c) provides a short account of presumably the same species. While brief, the description by Adams (1847c) of the carapace and legs validates the name. The modified fifth pereiopods and shell-carrying behaviour described by Adams argue against Caphyra pectenicola being a species of Caphyra Guérin, 1832 . This genus of portunid crabs is known to be symbiotic with various hosts, but does not have any appendages modified for carrying objects. Shell-carrying behaviour is known in the Dorippidae and Dromiidae (see Guinot & Tavares 2003; Holthuis & Manning 1990), but comments by Adams (1847c: 315) on Dorippe indicated he was familiar with these crabs. Amongst the dromiids, three genera: Austrodromidia McLay, 1993 , Conchoecetes Stimpson, 1858b , and Hypoconcha Guérin-Méneville, 1854 , are known to carry shells (see Guinot & Tavares 2003: 118–120). Of these, Hypoconcha occurs in the Americas, while Austrodromidia is apparently rare and known only from Australia ( Guinot & Tavares 2003: 50; McLay 1993: 123). Conchoecetes , however, is a widespread genus in the Indo-West Pacific with three known species (see Ahyong et al. 2009; McLay 1993; Ng et al. 2000) and they are known to carry bivalve shells of various types, including Pecten (unpublished data). Small specimens of Conchoecetes artificiosus ( Fabricius, 1798) , the most common species in Southeast Asian waters, do superficially resemble species of Caphyra , especially with regard to their relatively smooth and rounded carapaces and short legs. Caphyra pectenicola Adams, 1847c , is currently recognised as valid as Conchoecetes pectenicola (see McLay & Naruse, 2019: 34–37).

The usage of Caphyra pectenicola in Wood (1867: 225 , unnumbered fig.) is more problematic. The figure shows a dromiid crab with a smooth frontal margin resting in the shell of a Pecten . The drawing shows the pair of modified fifth pereiopods extended over the back margin of the carapace. The figure of Caphyra pectenicola in Wood (1867: 225) actually agrees well with members of Hypoconcha Guérin-Méneville, 1854 (see Guinot & Tavares 2003; McLay 1993). Species assigned to Hypoconcha Guérin-Méneville, 1854 , are found only in waters of North and South America ( McLay 1993: 123). Wood (1867) probably read the accounts by White (1847a) and Adams (1847c) of Caphyra pectenicola and identified his figure ( Wood 1867: 225, unlabelled figure) of Hypoconcha with the species, especially since they also use Pecten shells. Wood (1867: 225) was certainly aware of the collections of the British Museum as his preface states: “[…] the arrangement is that which is pursued in the splendid collections placed in the British Museum […]”. The same situation is probably true of the usage of this name by Hunter & Morris (1898: 4126), although they did not provide any figures. The use of this name by Wood (1867) and Hunter & Morris (1898) is here regarded as merely a subsequent citation of Caphyra pectenicola White, 1847a .