Calyptraeotheres camposi, Ayón-Parente, Manuel & Hendrickx, Michel E., 2014

Ayón-Parente, Manuel & Hendrickx, Michel E., 2014, Calyptraeotheres sp. nov. (Crustacea: Decapoda: Pinnotheridae), symbiont of the slipper shell Crepidula striolata Menke, 1851 (Mollusca: Gastropoda: Calyptraeidae) from the Gulf of California, Mexico, Zootaxa 3872 (1), pp. 89-94 : 90-93

Calyptraeotheres camposi sp. nov.

( Figs. 1–3 )

Material examined. Holotype: ovigerous female (CL= 3.1 mm; CW= 3.6 mm) (EMU-10361), off El Huizache, Sinaloa, 22°59'43''N, 106°15'37''W, 31 m, trawl, 1 August 2009. Paratypes: 1 ovigerous female (CL=3.0 mm; CW= 3.2 mm) (EMU-10362), off Altata, Sinaloa, Mexico, 24°40'53''N, 108°4'03''W, 14 m, trawl, 5 August 2009; 1 female (CL= 2.2 mm; CW= 2.4 mm) (EMU-10363), off Río Baluarte, Sinaloa, Mexico, 16 m, trawl, 16 April 2010; 1 ovigerous female (CL=4.0 mm; CW= 4.5 mm) (EMU-10364), off Teacapan, Sinaloa, Mexico 16 m, trawl, 26 June 2010.

Diagnosis. Carapace with antero-lateral margins arcuate and pilose, dorsally with a pair of well marked converging cervical depressions extending posteriorly from orbits to gastric region and connected by a transverse depression. Eyes visible in dorsal view. Maxilliped 3 placed obliquely, with palp of endopod 2-segmented. Ventral margin of propodus of chelae almost straight; inner surface of fixed finger with short setae near cutting edge and ventral margin.

Description. Female holotype. Carapace ( Fig. 1 A, B) slightly wider than long, front arcuate, slightly projecting forward, long plumose setae on anterior margin, and anterior three-quarters of antero-lateral margins; eyes visible in dorsal view; antero-lateral margins arcuate, dorsal regions ill-defined, posterior margin straight; a pair of cervical depressions running from orbits to gastric region, converging, connecting with a shallow, transverse depression. Maxilliped 3 ( Fig. 1 E, F) placed obliquely; exopod with unsegmented flagellum; endopod with ischium-merus fusion indistinct; merus widening distally, inner margin almost straight; palp 2-segmented, articulating distally on inner margin of merus; carpus longer than propodus, both subrectangular; propodus obliquely truncated. Chelipeds ( Fig. 2 A, B) stout; dorso-distal margin of carpus with rounded projection; chela longer than combined length of merus and carpus, palm widening distally, longer than dactyl, margins unarmed, fingers gaping when closed, tips crossing, dactylus curved, exceeding to fixed finger, cutting edge with proximal tooth, small teeth distally; fixed finger with proximal tooth, small teeth distally, inner surface with short setae near cutting edge and ventral margin. Relative length of ambulatory legs ( Fig. 1 C) in decreasing order 3>2>1>4, margins unarmed; ambulatory legs 1–3 similar in shape, 4th relatively slender. Dactyli of ambulatory legs acute, tip curved, relative length 4>3>2>1; dactyli shorter than propodi in ambulatory legs 1–3, longer than propodus in 4th. Abdomen ( Fig. 1 H) with 6 somites, telson distinctly separated, covering sternum, reaching buccal cavity.

Coloration. In life, carapace and ambulatory legs transparent, chelipeds white to pale-white. Ocular peduncles pale-white, cornea black ( Fig. 3 ).

Variation. The type series was carefully examined. Only small morphological variations were observed in the four specimens (the holotype and 3 paratypes) and these variations are attributed to size. Compared with mature females ( Figs. 1 A, C, E, F; 2A, B, E; 3), the immature female ( Figs. 1 D, G; 2C, D) has the front more produced and subrectangular, the third maxilliped is less setose, the numbers of distal teeth on the cutting edge of the dactyl and fixed finger are fewer (2 instead of 9–11 and 6 instead of 11–12, respectively), the setae on the inner surface and the ventral margin of the fixed finger are scattered, and the telson is subtriangular ( Fig. 1 I) instead of subcircular in mature females ( Fig. 1 H).

Etymology. This species is named in honor of our colleague and friend Ernesto Campos, Professor of Biology in the Facultad de Ciencias, Universidad Autónoma de Baja California, in recognition for his contribution to the taxonomy and ecology of pinnotherid crabs.

Distribution. Only know from the SE Gulf of California, Mexico.

Remarks. Hernández-Ávila & Campos (2006) separated the species of Calyptraeotheres in two sub-groups on the basis of the shape of the palp of the third maxilliped and the slipper shells in which they live. In the first group they included C. granti and C. hernandezi , both characterized by a 2-segmented maxilliped 3 palp and mainly symbionts of slipper shells of the genus Crucibulum (see Campos 1999). The second group consisted of C. garthi and C. politus , with a 3-segmented maxilliped 3 palp and mostly found associated with slipper shells of the genus Crepidula . Calyptraeotheres camposi sp. nov. is close to C. pepeluisi , C. granti , and C. hernandezi . Calyptraeotheres camposi sp. nov. can be distinguished from C. pepeluisi by the followings characters: the presence of a transversal depression connecting the pair of converging cervical depressions, absent in C. pepeluisi ; eyes proportionally shorter and robust; carpus and propodus of the third maxilliped subrectangular instead of the sub-trapezoidal carpus and sub-conical propodus of C. pepeluisi ; the cheliped dactylus exceeding the fixed finger, whereas the fixed finger overlapping the dactylus in C. pepeluisi ; the inner surface of the fixed finger bearing short setae near the cutting edge and ventral margin that are absent in C. pepeluisi . The new species can be distinguished from C. granti as follows: the carapace lateral margins are arcuate but subparalell in C. granti ; the eyes are visible in dorsal view, not visible in C. granti ; there is a transversal depression connecting the pair of converging cervical depressions instead of a faintly marked transverse groove that fails to connect with the subparallel longitudinal cervical grooves in C. granti ; the cutting edge of the fingers of the chelae bears more small denticles (9–12) than in C. granti (2 near the basis of dactyl and 3 on the fixed finger). According to Hernández-Ávila & Campos (2006: 48) in C. hernandezi there is a "well defined T-shaped transversal cervical sulcus [that] connects the longitudinal and curved sulci" [sic] and the carapace posterior margin is concave; ventral margin of the pollex bears minute setae instead of a dense fringe of setae, and only the dactylus of ambulatory legs 1–2 bears short setae on the ventral margin, whereas both dactylus and propodus of these legs are setose in C. camposi sp. nov. All the abovementioned characters are consistently observed in the type series of the new species.

Ecological remarks. All individuals of C. camposi sp. nov. were collected in symbiosis with live slipper shells Crepidula striolata Menke, 1851 . The slipper shell inhabited by the female holotype was found inside the dead shell of a specimen of the gastropod Hexaplex nigritus (Philippi, 1845) (Muricidae) occupied by the pagurid Petrochirus californiensis , and the slipper shells inhabited by the paratypes were found inside the dead shell of Hexaplex erythrostoma (Swainson, 1831) used by the pagurid Dardanus stimpsoni . Glassell (1936) and Williams & McDermott (2004) previously mentioned an association between the pinnotherid crab Calyptraeotheres granti (as Fabia granti ) that resides in the mantle cavity of Crepidula cf. nivea C.B. Adams, 1852 . Campos (1990), however, concluded that Crucibulum spinosum (Sowerby, 1824) is the preferred host of Calyptraeotheres granti , because this mollusk possesses a suitable space between the cephalic area and the shell for the crab to be able to grow to maturity.

Figures

FIGURE 1. Calyptraeotheres camposi sp. nov. A, B, E, F, H, holotype female (EMU- 10361); D, G, I, paratype immature female (EMU- 10363); C, paratype mature female (EMU- 10364). A, carapace, dorsal view; B, partial frontal view; C, dorsal view; D, carapace, dorsal view; E, third maxilliped, inner view; F, same, outer view; G, third maxilliped, inner view; H, abdomen, dorsal view; I, abdomen, dorsal view. Scale bars = A – D, H, I, 1 mm, E, F, G, 0.5 mm.

FIGURE 2. Calyptraeotheres camposi sp. nov. A, B, holotype female (EMU- 10361); C, D, paratype immature female (EMU- 10363); E, mature female paratype (EMU- 10364). A, C, right cheliped, outer view; B, E, tip of cheliped, inner view; D, right chela, inner view. Scale bar = 0.5 mm.

FIGURE 3. Calyptraeotheres camposi sp. nov. Paratype female (EMU- 10362). Scale bar = 2 mm.