Functional morphology of the copulatory system of box crabs with long second gonopods (Calappidae, Eubrachyura, Decapoda, Crustacea)

Abstract

Male True Crabs use two pairs of gonopods to deliver mating products during copulation. Commonly, the second pair is shorter than the first pair, and most research to date has focused on species with short second gonopods. We investigated male and female copulatory organs in Calappula saussurei and Calappa pelii, two species of box crabs (Calappidae) with second gonopods which are longer than the first pair. Scanning electron microscopy and histological cross sectioning show that the female copulatory system is unique in several aspects: the genital duct is part concave and part simple type. The seminal receptacle is divided into two chambers, a ventral chamber of ectodermal and mesodermal origin, and a dorsal chamber of ectodermal origin. This dorsal chamber is the location of spermatophore reception during copulation. A sperm plug closes the dorsal chamber off. We propose that long second gonopods deliver male mating products directly into the dorsal chamber. To date, spermatophore reception has been associated with the mesodermal tissue of the seminal receptacle. The copulatory system of box crabs with long second gonopods shows novel deviations from this general pattern.

Morphology of the female reproductive system of three dorippid crabs (Crustacea: Decapoda: Brachyura: Dorippidae) and the role of accessory cuticle structures associated with seminal receptacles

“…), Calappidae (Ewers‐Saucedo et al. ), and Leucosiidae (Hayer et al. ), supports the possibility that a ventrally located oviduct orifice and a concave vagina might actually be plesiomorphic characters.…”

“…), Pilumnidae (Hartnoll ), Calappidae (Ewers‐Saucedo et al. ), and Hymenosomatidae (Klaus et al. ), as well as in thoracotreme representatives of Varunidae (Lee & Yamazaki ), Ocypodidae (Lautenschlager et al.…”

“…), Calappa pelii Herklots 1851, and Calappula saussurei ( Rathbun 1898) (Ewers‐Saucedo et al. ), but the authors do not provide further details.…”

The morphology of the reproductive system in the crab Percnon gibbesi (Decapoda: Brachyura: Grapsoidea) reveals a new combination of characters in Thoracotremata

“…Small cuticle projections, very short setae or denticles along the tip of the G1 have also been described in several grapsoid species (Naderloo & Schubart, ; Naderloo, ) and in heterotremes, for example in Bythograeidae: Tsuchida & Fujikura (); Cancridae: Moriyasu, Benhalima, Duggan, Lawton, & Robichaud (); Epialtidae: Sal Moyano et al (); Calappidae: Ewers‐Saucedo et al () and Ewers‐Saucedo, Wares, Hanel, & Brandis (). The pappose setae that are grouped around the proximal opening in the G1 have previously been reported from gonopods of other species (Beninger et al, ; Minagawa, ; Brandis et al, ; Kienbaum et al, ).…”

“…Eubrachyuran crabs are supposed to have trans‐moult sperm retention because only the ventral part of the seminal receptacle is cuticle‐lined, while the rest is secretory (McLay & López‐Greco, ; but see Hayer et al, ; Vehof et al, ). The ratio of cuticle lining, on the one hand, and secretory lining, on the other hand can vary (Diesel, ; Jensen et al, ; Lautenschlager et al, ; Zara et al, ; Ewers‐Saucedo et al, ; de Souza et al, ; Kienbaum et al, ). In P. gibbesi only a small area dorsally in the seminal receptacle is lined by glandular epithelium, while the main part of the seminal receptacle is lined by cuticle.…”