Diogenes pugilator (Roux, 1829)

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 : 161-162

Diogenes pugilator (Roux, 1829)

( Fig. 6 )

Pagurus pugilator Roux 1829: 67 (unnumbered page), pl. 14 figs. 3–4.

Diogenes pugilator .— Forest, 1955: pg. 79, pl. 2 fig. 10 (syn. and ref.); 1956: 348, figs. 3–6; 1961: 222 (Tropical West Africa, 3–4 to 100 m).— Ingle, 1993: 46, figs. 9–12 (lit.).

Material examined. MU171, 105– 100 m, (1).

Male: 1.50 mm

Habitat. This species shows a preference for medium and fine sandy bottoms ( d’Udekem d’Acoz 1999) but is also reported on muddy sand, sandy mud, medium and coarse sands, debris and coralligenous bottoms ( Forest 1961; Dolbeth et al. 2006; García-Muñoz et al. 2008; El Lakhrach et al. 2012), associated with Posidonia oceanica (L.) Delile, 1813 meadows ( Sánchez-Jerez et al. 2000), in bottoms with the seaweed Caulerpa prolifera (Forsskål) J.V. Lamouroux, 1809 (López de la Rosa et al. 2002) and with Amphioxus sand (García Raso & Manjón-Cabeza 2002).

Diogenes pugilator shows a significant regional variability in its shell use. In Turkey, Mutlu & Ergev (2010) reported 27 inhabited gastropod species in the Levantine Sea, mostly of Nassarius gibbulosus (Linnaeus, 1758) , N. circumcintus (Adams A., 1852) , N. mutabilis (Linnaeus, 1758) , Strombus persicus (Swainson, 1821) and Littorina obtusata (Linnaeus, 1758) , while Ates et al. (2007) reported only shells of Ceritium and Gibbula on the Aegean coast. In southern Spain the most common gastropod shell species were Mesalia varia (Kiener, 1887) , Turritella communis Risso, 1826 , Nassarius reticulatus (Linnaeus, 1758) , Nassarius mutabilis (Linnaeus, 1758) , Turritella turbona Monterosato, 1877 and Gibbula magus Linnaeus, 1758 , but another 32 species (including scaphopods and polychaete tubes) were listed by Manjón-Cabeza & García Raso (1999). In southern Portugal, D. pugilator was mostly found in Nassarius sp (as Hinia sp), Turritella sp and Gibbula sp. shells ( Dolbeth et al. 2006). In the German Bight, the species was mainly found inhabiting Littorina littorea (Linnaeus, 1758) (plus another seven shells) ( Türkay 2014), whereas on the Irish coast, McGrath et al. (2000) found the species mostly living in Nassarius reticulatus (Linnaeus, 1758) , but also in Nucella lapillus (Linnaeus, 1758) , Littorina littorea (Linnaeus, 1758) , L. obtusata agg. and Gibbula umbilicalis (da Costa, 1778).

In West Africa the species was found in Clavatula nifat (Adanson) Bruguiere , Chicoreus varius (G. B. Sowerby II, 1834) (as Murex varius ), Murex sp., Nassa sp., Natica collaria Lamarck, 1822 , Natica fulminea (Gmelin, 1791) , Agaronia hiatula (Gmelin, 1791) (as Olivancillaria (Agaronia) hiatula ), Turritella annulata Kiener, 1843 and Turritella sp. ( Forest 1955, 1956).

The single specimen captured during the Maurit surveys inhabited a gastropod shell of the family Nassariidae that was considerably damaged during crab extraction.

Epibiotic and free-living species associated with D. pugilator are the protozoan Acinetides symbiotica (Daday, 1907) , the hydrozoan Podocoryna exigua (Haeckel, 1879) , the plathyhelminthe Leptoplana tremellaris (Müller, 1774) , the polychaete Polydora ciliata (Johnston, 1838) and the copepod Sumaristes paguri Hesse, 1867 ( Williams & McDermott 2004). Forest (1955) found this species associated with bryozoans and with zoanthids of the genus Palythoa .

Distribution. This species has been reported evenly distributed in the eastern Atlantic from the western and southern Irish coasts ( McGrath et al. 2000) and from the North Sea southwards to Angola, including the Cape Verde Islands and the Mediterranean Sea. The species was also found in the Black and Red Seas ( d’Udekem d’Acoz 1999).

Further records that fit well with this distribution can be found in Sánchez-Jerez et al. (2000), Koçak et al. (2001), López de la Rosa et al. (2002), Pipitone & Arculeo (2003), Dolbeth et al. (2006), Serrano et al. (2006), García-Muñoz et al. (2008), Mutlu & Ergev (2008 and 2010), Koçak et al. (2010), Pipitone & Vaccaro (2011), El Lakhrach et al. (2012) and Türkay (2014). D. pugilator is reported here for the first time in Mauritanian waters.

D. pugilator has been found living mostly from the intertidal zone ( d’Udekem d’Acoz 1999) to 40–50 m ( Forest 1961; Türkay 2014), but also in depths of about 100 m ( Forest 1961 in Nigeria; present record) and from 201 to 400 m depth ( Serrano et al. 2006 in the Cantabrian Shelf).

A record from 1800 m depth reported by Neves (1977) was considered erroneous by d’Udekem d’Acoz (1999).

Remarks. Our specimen fits well with the description and figures given by Ingle (1993) and with the variations described and figured by Forest (1956).

Only five Diogenes species were reported from tropical West Africa ( Barnard 1950; Forest 1955, 1956). Our specimen can be easily differentiated from Diogenes brevirostris Stimpson, 1858 and Diogenes denticulatus Chevreux & Bouvier, 1891 by the ocular acicles, whose distal margin slopes outwards and are cut into four graded processes of which the innermost is the largest and more acute versus the 10–12 similar serrations in the other two species. Diogenes mercatoris Forest, 1952 differs by the presence of short, strong spines disposed in transversal rows on both sides of the carapace shield, the shortness of the interocular process, and the long and dense setae on the chelipeds and ambulatory legs versus no spinose transverse rows on the shield, long interocular process and scarcely setose chelipeds and ambulatory legs in D. pugilator . Diogenes ovatus Miers, 1881 shows a conspicuous depression at the base of the left cheliped carpus housing pereiopods 2 and 3 when retracted, which is absent in D. pugilator .

Variability for this species was demonstrated and discussed by Forest (1955, 1956). Our specimen closely resembles those collected in Ghana and figured by Forest (1956: figs. 3A, 5), with only one difference: the presence of two small spines instead of one on the anterolateral margins of the shield. We consider that this is to be minor intraspecific variation.

Figures

FIGURE 6. Diogenes pugilator (Roux, 1829). Male, sl: 1.50 mm (MU 171; UVIGOBA 3 13296): A, shield and cephalic appendages. B, chelipeds: left, lateral view, right, ventrolateral view. Scale: A, 0.5 mm; B, 1 mm.