Areopaguristes mauritanicus ( Bouvier, 1906 ) Bouvier, 1906

De Matos-Pita, Susana S. & Ramil, Fran, 2015, Hermit crabs (Decapoda: Crustacea) from deep Mauritanian waters (NW Africa) with the description of a new species, Zootaxa 3926 (2), pp. 151-190 : 157-158

Areopaguristes mauritanicus ( Bouvier, 1906) n. comb.

( Figs. 2–4 )

Paguristes mauritanicus Bouvier 1906: 186 , fig. 1.— Forest, 1954a: 179, figs. 16, 31, 44, 56; 1955: 54, fig. 8, pl. 1 figs. 7–9 (ref.); 1956: 343 (syn.); 1961: 215 (in part) [ Guinea to Angola, 32 to 74– 49 m, not those in Gabon transferred to P. cyanops by Forest (1978)]; 1966: 141 ( Guinea-Bissau to Gabon, 18 to 100– 90 m; São Tomé and Príncipe, 4 to 10– 12 m). Paguristes skoogi Odhner, 1923: 6 , pl. 1 (in part, see Forest 1956: 344).

Material examined. MU 266, 103 m, (1); MUBV 21, 107– 109 m, (2).

Males: 2.98–3.70 mm

Type material. Holotype: Mauritanie, au large de Nouakchott, 16–24 m, 1905, no. 37, Bouvier det. [MNHN- IU-2008-14993 (= MNHN-Pg1619)], adult male, sl 3.91 mm, left and right chelipeds, both third pereiopods and left second pereiopod detached, both first pleopods missing, in a shell of the gastropod genus Cancellaria .

Additional material. IFAN, Senegal, M’Bao, 7.2.51, à 1 mille de la côte, 5–14 m, Delais coll., J. Forest det. 1952 [MNHN-IU-2013-13176 (= MNHN-Pg1617)]; adult male, sl 2.34 mm, entire but with left second pereiopod detached; adult female, sl 1.47 mm, left cheliped missing, inside the carcinoecium built up by the bryozoan Hippoporidra picardi Gautier, 1962 .

IFAN-BIOLOGIE MARINE, Senegal, Baie de Gorée, 15–20 m, J. M. Marchard coll. [MNHN-IU-2013-13178 (=MNHN-Pg1620)]; adult male, sl 2.15 mm, entire; three adult females, sl 1.81, 1.82 mm (entire) and 1.99 mm (right third pereiopod missing).

Habitat. Reported from muddy bottoms but also on muddy sand, sand, shell sand, coarse shell sand, gravel, shells, calcareous algae, debris, bryozoans, foraminifers and rock ( Forest 1954a, 1955, 1961, 1966).

This species was reported inhabiting shells of the genera Bullia , Cancellaria , Clavatula , Gibbula , Marginella , Mesalia , Nassa , Terebra , Trophon , Turritella , etc ( Forest 1954a) and in shells of Drillia rosacea (Reeve) , Nassa sp, Persicula cingulata Dillwyn , Clavatula rubrifasciata Reeve , Murex sp., Phos grateloupianus Petit de la Saussaye, Turris sp. and Turritella annulata Kiener ( Forest 1955, 1956).

The bryozoan Hippoporidra picardi Gautier, 1962 was reported as a symbiont species associated with the gastropod shells inhabited by Areopaguristes mauritanicus n. comb. ( Williams & McDermott 2004; as Paguristes mauritanicus ).

Our specimens were collected in shells of the genera Fussiturris and Genota .

Distribution. From Rio de Oro (SW Sahara, 21°30'N. 17°05'W) ( Forest 1961) to Angola (about 16°S) ( Forest 1978: 537); depth ranges from 4 m ( Forest 1966: 142) to 107–109 m (present work).

Remarks. Our specimens concur with the type material examined during this study, and with the detailed description and figures given by Forest (1954a, 1955).

During the study of Maurit material we found only 12 pairs of functional gills in our specimens; no pleurobranchiae on the second thoracic segment were observed. The same gill formula was observed in the revision of the holotype and other African material from the MNHN. The genus Paguristes is characterized by 13 pairs of gills and Rahayu (2005) erected the genus Stratiotes (= Areopaguristes ) to accommodate the species previously included in Paguristes with 12 pairs of gills. Following Rahayu (2005) and after the revision of the holotype, we concluded that Paguristes mauritanicus should be transferred to Areopaguristes .

Areopaguristes difficilis ( Forest 1952c; as Paguristes difficilis ) is closely related to A. mauritanicus , but the differences in the morphology of the chelipeds (subtriangular in A. difficilis versus oval in A. mauritanicus ) and of the male first pleopods (inferior lamella two and a half times longer than wide and with distal hook-like spines distally versus about four times longer than wide and unarmed) can be used to separate both species. Forest (1978) described Paguristes cyanops (= Areopaguristes cyanops ) as also closely related to A. mauritanicus , but the morphology of the male pleopods 1 and 2 is a reliable indication that the two species are separate. Forest (1978) described the tuft of setae on the inner face of pleopod 2 of A. mauritanicus with convergent setae. However, after checking the holotype, we noticed that these setae are not as convergent as those described for A. mauritanicus ( Forest 1978: fig 13) but divergent, as those figured for A. cyanops ( Forest 1978: fig. 11). This same divergence was observed in our specimens ( Fig. 4 ). The morphology of pleopod 1, coincident with the description of Forest (1952c, 1978), and the ocular peduncles with a uniform and equal diameter and a white proximal colouration that becomes light red distally, upholds the identification of our specimens as A. mauritanicus .

Forest (1955, 1966, 1978) suggested a certain relation between latitude and depth, with a shallower distribution to the north. However, our findings from 107–109 m depth do not support this relation and constitute the deepest record for the species, similar to bathymetric records reported from Gabon and Ghana ( Forest 1954a, 1966; to 100 m).

Figures

FIGURE 2. Areopaguristes mauritanicus n. comb. Shields: left, adult male, sl: 3.70 mm (MU 266; UVIGOBA 3 - 02671); right, holotype, adult male, sl: 3.91 mm [MNHN-IU- 2008 - 14993 (= MNHN-Pg 1619)]. Scale bar, 1 mm.

FIGURE 3. Areopaguristes mauritanicus n. comb. Chelipeds, left (top) and right (bottom), lateral view: A, Holotype, adult male, sl: 3.91 mm [MNHN-IU- 2008 - 14993 (= MNHN-Pg 1619)]. B, adult male, sl: 3.70 mm (MU 266; UVIGOBA 3 - 02671). Scale bars A, B, 1 mm.

FIGURE 4. Areopaguristes mauritanicus n. comb. Holotype [MNHN-IU- 2008 - 14993 (= MNHN-Pg 1619)], left pleopod 2. Scale, 1 mm.