Pagurus pseudosculptimanus, Muñoz, J. Enrique García, Cuesta, Jose A. & Raso, J. Enrique García, 2014

Muñoz, J. Enrique García, Cuesta, Jose A. & Raso, J. Enrique García, 2014, Taxonomic study of the Pagurus forbesii " complex " (Crustacea: Decapoda: Paguridae). Description of Pagurus pseudosculptimanus sp. nov. from Alborán Sea (Southern Spain, Western Mediterranean Sea), Zootaxa 3753 (1), pp. 25-46 : 35-36

Pagurus pseudosculptimanus sp. nov.

( Figs. 7–12 , 13 B)

Eupagurus sculptimanus .— Chevreux & Bouvier 1892: 104, pl. II, figs 18–29.— Bouvier 1896: 149, fig. 13.— Forest 1955: 125.

Material examined. "Calahonda" Mijas littoral—Málaga (Alboran Sea, Spain), 36°28.0’N, 04°42.3’W, 25 m: 25– 26/11/2004, 4 ♀♀, 4♂♂; 09/02/2005 (2 samples), 17 ♀♀, 13♂♂; 18/05/2005, 27 ♀♀, 19♂♂.

Type material. "Calahonda" Mijas littoral—Málaga (Alboran Sea, Spain), 36°28.0’N, 04°42.3’W, 25 m, 18/ 05/2005. Holotype: adult male, carapace shield length 3.8 mm, MNCN ( CSIC) 20.04/9147 Madrid. Paratypes: 1 male MNCN ( CSIC) 20.04/9148, 1 female MNCN ( CSIC) 20.04/9149, Genbank accession numbers KF962982 -83 / KF962986 -87; 3 specimens, MNHN; 39 specimens, Department of Biología Animal, University of Málaga.

Description. Cephalothoracic shield ( Fig. 7 A). Anteromedial frontal margin not protruding and rounded off; blunt anterolateral processes. Cephalothoracic shield about as long as wide, ratio length/ width 1.01–0.9. Cervical groove deep and distinct. Shield length / ocular peduncle length = 1.3.

Eyes. Long and narrow eyestalk with cornea slightly expanded. Ratio total length / maximum width (cornea) about 2.5–2.7 (shorter than P. forbesii ). They reach nearly to the tip of the antennal peduncle and about the middle of the third segment of antennular peduncle. Sub-triangular ocular acicles, with submarginal apical spine and slightly convex inner face.

Antennules ( Fig. 7 B). First segment with outer medial spine. Ratio of length / width third segment = 3.3–3.6. Ratio third/ second segment length = 1.5. Endopod 8-segmented.

Antenna ( Fig. 7 C). Segment 1 with outer subdistal spine and ventromesial distal spine. Strong dorsolateral process on second segment of antennal peduncle with 3 teeth on inner edge, not reaching beyond proximal half of fourth segment. Antennal acicle slightly curved, not reaching middle of fifth segment, reaching or overreaching base of cornea but not beyond it extremity.

Mouthparts: Mandibles ( Figure 7 D) with 3-segmented palp. Maxillule ( Fig. 7 E) endopod distally expanded into inner elongated lobe, usually with long, apical setae and outer distal part expanded in rounded broad lobe. Maxillae ( Fig.7 F) with 3 or 4 subdistal setae on palp. Maxilliped 1 ( Fig. 7 G) exopod peduncle broadened proximally, distal part of endopod reaching the half of exopod peduncle. Maxilliped 2 as figured ( Fig. 7 H). Maxilliped 3 ( Fig 7 I) outer distal margin of carpus and merus without spines; proximal dorsomesial margin of ischium with 2 subacute processes, crista dentata with 16 or 17 subacute processes and 1 accessory distal tooth; basipod with 2 teeth.

Right cheliped ( Figs. 8 A, 11F–H) much larger than the left. In lateral view, edge of upper surface planar, with central ridge separating 2 lateral areas (sometime concave). Distinct central blunt ridge following straight line, from strong proximal-central tubercle to strong medium palmar one, behind basal inner part of fixed finger (different in P. f o r b e s i i). Both prominences higher than central blunt ridge (in different grade). Third smaller proximal inner prominence on propodus. Straight ridge defining 2 depressions (sometimes very conspicuous) with different morphologies from those of Pagurus forbesii ; outer large depression and other inner smaller depression with similar width proximally and distally. Third depression defined by fingers, each with rounded median ridge from which surface slopes rapidly downwards to form hollow between fingers. Upper palmar surface with rounded granules, which can be developed as tubercles in the prominences. Outer margin of hand convex, with row of strong, distinct teeth on its total length. Inner margin, from base of protopod to tip of dactylus almost straight, dactylus curving towards fixed finger only near tip, and also with row of strong, well developed blunt teeth. Ventral surface of hand almost smooth, with few tubercles. Fingers end in yellow claws. Upper (dorsal) surface of carpus denticulate with teeth. Merus with upper surface smooth, distal ventral margin denticulate. Ischium ventral keel with small denticles and setae, and row of small tubercles with 5 setae in distal-outer-medial part.

Left cheliped ( Figs. 8 B, 11I) much smaller than right. Dactylus longer than half palm and fixed finger length.

Fingers end in yellow claws. Base of fixed finger much broader than dactylus at is base. Dorsal surface of palm convex transversely in its central part and with proximal outer margin concave, which shows feeble depression with outer row of strong teeth oriented upwards. Palmar upper surface with rounded granules little more developed in upper central part and mainly on a proximal prominence with tubercles. Cutting edge of the dactylus furnished with long row of slender transparent spines. Carpus dorsally spinous with medial row of 4–6 strong teeth, ventral area granulate with long setae. Merus with ventral tubercles and teeth, more developed in distal outer and inner margins, and long setae. Ischium with ventral inner keel and row of 10–12 small teeth and setae, with some small distalolateral tubercles.

Pereiopod 2 ( Fig. 9 A). Left with ratio merus / ischium length = 3.7–4.0. Merus: with 2 or 3 distoventral teeth, upper face smooth, unarmed. Carpus with 4–7 upper teeth. Propodus with 9 small dorsal spinous tubercles, ventrally smooth. Dactylus with articulate spines, but without teeth.

Right second pereiopod ( Fig. 9 B) with ratio merus / ischium length = 4.5–5.0. Ischium smooth. Merus with 1– 3 small ventrodistal teeth, upper face smooth. Carpus with 6–10 upper strong teeth. Propodus with 9–11 teeth on dorsal margin. Dactylus with slender articulate spines, but without teeth.

Pereiopod 3. Longer than second pereiopod. Left ( Figs. 9 C, 11I) with ratio merus / ischium length = 1.3–1.4. Ischium and merus dorsally smooth. Carpus with 1–3 dorsodistal teeth. Propodus smooth dorsally and with 3–6 denticulate tubercles ventrodistally. Dactylus without teeth but with ventral articulated spines extending from distal to proximal part.

Right P3 ( Fig. 9 D) with ratio of merus/ischium length = 1.6–1.8. Ischium and merus smooth, merus sometimes with small articulated spines. Carpus and propodus ventrally smooth, dorsally with small denticles (or absent). Dactylus with articulated spines, but without teeth.

Anterior lobe of sternite of third pereiopods ( Fig. 9 E) subtriangular, setose, with strong acute spines on distal margins.

Pereiopod 4 ( Fig. 10 A). Dactylus with 14 or 15 ventral spiniform setae, ending in hyaline blunt claw. Outer ventral area of propodus with numerous spatulate to subacute pseudochaetae.

Pereiopod 5 ( Fig. 10 B). Dactylus spatulate with 24 spines on distal margin. Propodus with dorsodistal area with pseudochaetae.

Males with second to fifth pleopods on the left side. Pleopod 2 ( Fig. 10 C) endopod absent or highly reduced as small projection, "lamina"; third to fifth pleopods ( Figs. 10 D–F) with endopod length half that of exopod length.

Uropods. Left about twice size of right, both with pseudochaetae on the distal part of endopod and exopod.

Telson ( Fig. 10 G) bilobed with median cleft. Left and right lobes similar in size, left slightly larger than right, with 11–14 distal subacute processes, largest outermost.

Morphological remarks. The principal, easily observable morphological differences between P. forbesii and P. pseudosculptimanus , are in the morphology of right cheliped (central ridge and tubercles) ( Fig. 11B–D , F–H) and the dactylus of the left third pereopod (with strong teeth in P. forbesii ) ( Fig. 11E – I). Other differences are in the length / width ratio of the eyestalks (total length / maximum width (cornea)), and in the third segment of the antennular peduncle (length / width (in the middle)).

Etymology. the species name is a combination of the words " sculptimanus ", in allusion to the morphology of large cheliped, and "pseudo", based on the invalidity of this name (synonymy of Pagurus forbesii ) given to some specimens in old references.

Distribution. Mediterranean Sea: Spain (in Alborán Sea between 15–25 m depth) and East Atlantic Ocean: Morocco to Senegal (see discussion).

Habitat and associated species. The species inhabits the continental shelf on medium sandy bottoms with bioclasts, “detritic bottoms”. Characteristics: 0.250 <Q50 <0.500 (Q50 = 0.466). % clay (% <0.063) = 2.5. % gravel (%>2.00) = 8.8. % bioclasts (%> 6.30) = 3.5. % organic material = 1.97 ± 0.41 sd.

Other species of hermit crabs found on this bottom, at 25 m depth, were (by abundance): Diogenes pugilator (Roux, 1829) , Anapagurus hyndmanni (Bell, 1845) , Paguristes eremita (Linnaeus, 1767) , Dardanus arrosor (Herbst, 1796) , Pagurus cuanensis Bell, 1845 , Anapagurus alboranensis Garcia-Gomez, 1994 , Calcinus tubularis (Linnaeus, 1767) , Pagurus prideaux Leach, 1815 , Pagurus excavatus (Herbst, 1791) , Anapagurus chiroacanthus (Lilljeborg, 1856) , Anapagurus petiti Dechancé & Forest, 1962 , Dardanus calidus (Risso, 1827) and Cestopagurus timidus (Roux, 1830) .

Figures

FIGURE 7. Pagurus pseudosculptimanus n. sp., holotype. A, anterior part of body. B, right antennule (outer view). C, antenna, right dorsal view and of proximal segments in ventral view. D, right mandible (outer view). E, left maxillule (inner view). F, left maxilla (outer view). G, left first maxilliped (inner view). H, right second maxilliped (inner view). I, right third maxilliped (outer view). All scales 1 mm. Setation not shown.

FIGURE 8. Pagurus pseudosculptimanus n. sp., holotype. A, right cheliped (outer view) and detail of basal segments (inner view). B, left cheliped (inner view) and details (palm in outer and dorsal views). All scales 1 mm. Setation not shown.

FIGURE 9. Pagurus pseudosculptimanus n. sp., holotype. A, left second pereiopod (inner view). B, right second pereiopod (inner view). C, left third pereiopod (inner view). D, right third pereiopod (inner view). E, sternal plate. All scales 1 mm. Setation not shown.

FIGURE 10. Pagurus pseudosculptimanus n. sp. A, left fourth pereiopod (outer view). B, left fifth pereiopod (outer view). C, second pleopod (from two specimens). D – F, third to fifth pleopods. G, telson (dorsal view). All scales 1 mm. Setation not shown. Holotype, less left C (male 18 / 05 / 2005)

FIGURE 11. A – E, Pagurus forbesii; F – I, Pagurus pseudosculptimanus n. sp. A, cephalothoracic region (dorsal view). B – D, right cheliped (lateral and dorsal views). E, dactylus and distal part of propodus of left third pereopod (lateral view). F – H, right cheliped (dorsal and lateral views). I, dactylus and distal part of propodus of left P 3 (lateral view).

FIGURE 12. Pagurus forbesii: syntypes of Pagurus sculptimanus Lucas. A, D, right chelipeds (dorsal view of propodus and dactylus). B, right cheliped (inner view). C, left third pereiopod (outer view). A – C, MNHN-IU- 2009 - 3929 (= MNHN-Pg 343); D, MNHN-IU- 2008 - 15134 (= MNHN-Pg 343).

FIGURE 13. Junction of both chelipeds to close the mouth of the shell in: A, Pagurus forbesii; B, Pagurus pseudosculptimanus n. sp.; C, Pagurus alcocki (MNHN-IU- 2009.2296).