Paguristes candelae, De Matos-Pita, Susana S. & Ramil, Fran, 2015

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 : 164-170

Paguristes candelae n. sp.

( Fig. 7–12 )

Material examined. Holotype: Stn. MU140 (17°39'25"N, 16°38'11"W to 17°42'28"N, 16°38'00"W), 376–377 m, 4 November 2008 ( MNCN 20.04/9822), male, sl 9.54 mm, entire, part of the anterior right branchiostegite is missing, inhabiting a shell of Euthriostoma saharicum (Locard, 1897) attached with two specimens of an unidentified actinia.

Paratypes: Stn. MUBV 18 (18°28'27" N, 16°42'43"W to 18°28'14"N, 16°42'40"W), 559–574 m, 11 December 2009 ( MNCN 20.04/9823), 1 female, sl 5.10 mm, entire, lacking right pereiopod 4 dactylus and half propodus, without a shell; Stn MUDR 12 (19°52'38"N, 17°22'23"W), 485 m, 26 November 2010 (UVIGOBA3–02500), 1 female, sl 3.91 mm, entire, right P3 and left P2 detached, inhabiting a shell of Nassarius wolffi (Knudsen, 1956) (specimen added posteriorly, collected in the same area with a rock dredge).

Description. Shield slightly longer than broad (1.04 times); anterolateral margins weakly sloping, one spine on anterolateral angle; anterior margin between rostrum and lateral projections concave; posterior margin truncated; dorsal surface rugose with low, irregular elevations on gastric region on either side of the midline and scattered tufts of long simple setae laterally ( Fig. 8 A).

Rostrum short, broadly triangular, with a terminal thin spine weakly curved ventrally, falling short in relation to the lateral projections; dorsal surface with a median elevation; lateral margins smooth and furnished with long plumose setae. Lateral projections subtriangular, with small and weakly developed marginal blunt spines on the left, not developed on the right ( Fig. 8 B).

Branchiostegites strongly calcified ( Figs. 7 A, B), anterior margin smooth and furnished with long plumose setae on the left (right is missing); covering 13 pairs of biserial phyllobranchiae; pleurobranchiae above pereiopods 2–4.

Ocular peduncles moderately slender (5.85 times longer than the width of cornea), about 0.54 times as long as shield, cylindrical, weakly inflated basally, cornea not dilated; both dorsal surfaces with dorsolateral tufts of long simple setae proximally and a longitudinal dorsomesial row of long simple setae ( Fig. 8 B).

Ocular acicles subtriangular, ending in a simple spine on the left and with an additional small spine behind the main one ( Fig. 8 B); mesial and lateral margins unarmed; mesial margin furnished with short plumose setae; separated by 0.3 basal width of one acicle.

Antennular peduncles, when fully extended, overreach distal margins of corneas by 0.8 length of ultimate segment. Ultimate segment with a dorsal longitudinal row of scattered long, simple setae; penultimate segment without setae. Basal segment with spine on dorsolateral margin of statocyst lobe, laterodistal margin with spinule, ventromesial distal angle produced, ending in acute spine.

Antennal peduncles, when fully extended, overreach cornea by 1/3 the length of the fifth segment; fifth segment unarmed; fourth segment with a small spine at dorsodistal margin; third segment with ventromesial distal angle strongly produced, ending in a strong spine; second segment with dorsolateral distal margin produced, ending in three spines almost concealed by a tuft of long simple setae, lateral margin with a small spine on the left antenna and smooth on the right one, dorsomesial angle with two distal spines, mesial row of short plumose setae; first segment with a very small laterodistal marginal spine on the left antenna, unarmed on the right one. Antennal acicles moderately long, slightly falling short of the distal margin of the ultimate peduncular segment, with numerous long simple setae; ending in a strong bifid spine; inflated basally; mesial margin with eight (left) or seven (right) strong spines, lateral margin armed distally with two (right) or three (left) strong spines ( Fig. 8 B). Antennal flagella three times the length of the shield, slightly exceeding the tips of chelipeds, composed of about 50 articles, each with simple setae on their distal margin; setae up to six articles long.

Third maxilliped ischium with well-developed crista dentata composed of moderately sized corneous teeth, without accessory tooth, ventrodistal margin and dorsolateral corner with one spine; merus with three moderate and separated ventral spines, one spine on dorsodistal margin; carpus with one spine on dorsodistal margin; dactylus shorter than propodus ( Fig. 10 D).

Chelipeds subequal and with similar armature, left slightly large and longer than right ( Fig. 7 C). Dactylus 1.5 times longer than palm, cutting edge with a row of small calcareous teeth in proximal 0.7 and a row of strong corneous teeth in distal 0.3, ending in a strong corneous claw, overlapped by a fixed finger; dorsomesial margin with an irregular row of moderately small, conical, corneous-tipped spines, decreasing in size distally, dorsal surface with scattered tufts of long stiff setae and a couple of spinulose tubercles proximally; mesial face protuberant ventrally ( Fig. 10 B) with scattered tufts of short setae and corneous, or only corneous-tipped, spinules; ventral surface unarmed, with tufts of stiff setae. Palm slightly shorter than carpus ( Fig. 10 A); dorsomesial margin with three strong, corneous-tipped spines, dorsal surface convex, without delineation of dorsolateral margin, with several irregular rows of moderately strong, corneous-tipped spines, decreasing in size on the fixed finger, and with a tuft of stiff setae; mesial surface with a couple of low protuberances distally, with tufts of long setae, mesiodistal margin unarmed; ventral surface well inflated, with row of spinulose tubercles with tufts of long setae along midline, extending onto the fixed finger, and few protuberances or tubercles laterally and mesially. Fixed finger not noticeably deflexed ( Fig. 10 B); dorsal surface with irregular rows of moderately strong corneous-tipped spines, decreasing in size distally; lateral margin not clearly delineated; cutting edge with row of small calcareous teeth in proximal 0.7 and row of strong corneous teeth in distal 0.3, ending in a strong corneous claw; a narrow hiatus when the claw is closed. Carpus about 0.6 times as long as merus ( Fig. 10 B); dorsomesial margin with an irregular row of four or five strong, conical, corneous-tipped spines, increasing in size distally; dorsal surface with single or double row of moderately strong, corneous-tipped spines at both sides of the midline and scattered tufts of long single setae; dorsodistal margin produced, with moderately small corneus-tipped spine laterally; dorsolateral margin not clearly delineated; mesial surface with tufts of setae along dorsal and distal margins; lateral surface with some scattered and moderately small tubercles, with tufts of setae; laterodistal margin with few small spines dorsally; ventral face unarmed. Merus moderately deep; dorsal surface with a row of small spinulose tubercles with tufts of long simple setae; dorsodistal margin weakly spinulose, with a spinulose transverse ridge running subdistally from lateral to mesial faces; mesial surface smooth; ventromesial margin with a row of moderately strong, corneoustipped spines and sparse simple setae; lateral surface with scattered small tubercles and few short setae ( Fig. 10 B); ventral face unarmed and with a row of plumose setae distally following the ventrolateral margin; ventrolateral margin with small spine near distal corner. Ischium with a row of small spinulose tubercles, increasing in size distally, furnished with plumose setae on ventromesial margin, ventrolateral distal angle with a couple of small spines. Coxa unarmed.

Second pereiopods overreaching chelipeds by about the total length of the dactylus ( Figs. 7 A, 9A). Dactylus about 0.6 times longer than propodus; weakly curved in lateral view, nearly straight or slightly twisted in dorsal view; ending in a strong, curved, corneous claw; each dorsal surface with a row of small to moderately small corneous-tipped spines, becoming smaller distally, partially obscured by numerous tufts of long setae; each mesial face with two rows of tufts of setae dorsally and ventrally ( Fig. 10 C); lateral faces with two rows of sparse tufts of setae subdorsally and subventrally; each ventral margin with a row of about 30 small corneous spines anteriorly directed, increasing in size distally. Propodus distinctly longer than carpus; dorsal surfaces each with a more or less irregular row of strong, corneous-tipped spines mesially, less numerous on left pereiopod, partially obscured by tufts of long setae; dorsodistal margins with a spine; mesial surfaces with two entire rows of tufts of long setae dorsally and ventrally and one short row of scattered tufts of long setae on the proximal midline; lateral surfaces unarmed, each one with a row of tufts of long setae near the dorsal and ventral margins and also on the midline; ventral surfaces unarmed, each with an irregular row of tufts of long setae. Carpus dorsal surface with a row of strong, corneous-tipped spines mesially and tufts of long setae ( Fig. 10 C), dorsodistal margin with a strong corneus-tipped spine; mesial surfaces smooth; lateral faces convex, each one with shallow longitudinal sulcus irregularly lined with scattered tufts of long simple setae, median scattered tufts of long simple setae and one row of lateroventral tufts of long simple setae; smooth ventral surfaces with a couple of tufts of short simple setae; ventrodistal margins with some long simple setae and a few short plumose setae. Merus strongly compressed laterally; each dorsal surface with a row of tufts of long simple setae; mesial and lateral surfaces smooth; each ventral surface with a mesial row of small spines or spinules and numerous long simple setae with some short plumose setae, ventrolateral angle furnished with two short plumose setae. Ischium dorsal surfaces with a row of spinules and some short plumose setae, dorsodistal margins with a short spine; ventral margins with a distal row of long plumose setae. Coxa unarmed other than with small spines on ventrolateral and ventromesial distal angles.

Third pereiopods mostly similar to second in setation ( Figs. 7 A, 9A). Dactylus with a proximal single row of small corneous-tipped spines and small corneous spines distally on dorsomesial margin; each mesial surface with a single or a double row of small corneous spines ventral to midline ( Fig. 10 C); each ventral surface with a row of about 30 small corneous spines anteriorly directed, flanked by two rows of tufts of long setae. Propodus unarmed. Carpus with a dorsal row of 2 or 3 spines proximally and a subdistal dorsal spine; mesial faces with one mediodistal tuft of setae ( Fig. 10 C). Merus unarmed apart from a few spinules proximally on dorsal surfaces. Ischium with some barely noticeable spinules on dorsal surface and a very small subdistal spinous low tubercle. Coxa unarmed on dorsal and ventral margins.

Fourth pereiopods setose on dorsal and ventral margins. Dactylus weakly curved, ending in a strong corneous claw, without preungal process ( Fig. 10 E); dorsal surface unarmed; ventral surface with a lateral row extending to 0.7–0.8 length of ventral margin and composed of 6 or 7 corneous teeth. Propodal rasp formed by 5–6 rows of ovate scales ( Fig. 10 E). Carpus and merus unarmed.

Fifth pereiopods chelate, setose. Dactylus covered with ovate scales ( Fig. 10 F). Propodus with a welldeveloped rasp ( Fig. 10 F). Each coxa with a gonopore.

Pleopods. First and second pleopods paired and modified ( Figs. 11 A, 11B). First pleopod robust, inferior lamella with the distal rounded margin furnished with 2–3 rows of hook-like spines ( Fig. 11 C); external lobe with a curved tip and separated from the internal lobe by a wide rounded notch ( Fig. 11 C); broad internal lobe with long setae distally ( Figs. 11 A, 11C). Second pleopod uniramous ( Fig. 11 D). Third to fifth pleopods unpaired, exopods very well developed, endopods rudimentary.

Abdominal tergites. Second and third abdominal tergites moderately calcified on their left ( Fig. 7 B), with long plumose setae on the left margins; fourth abdominal tergite widely separated from the third tergite, with moderately long plumose setae.

Uropods strongly asymmetrical ( Fig. 9 D); each protopod with a few small corneous-tipped spines on its posteroventral margin.

Telson with posterior lobes somewhat asymmetrical, left lobe larger than the right; broadly rounded; separated by a wide median cleft; terminal margins with short broad spines, 7 (left) and 6 (right) ( Fig. 11 E); deep transverse indentations (as in Fig. 9 D); anterior lobes unarmed on their lateral margins.

Females. Differences other than those attributed to sex: relative length of the antennal penduncle that falls short of distal cornea; absence of subterminal spine in the ocular acicles ( Fig. 9 B); spines on ventrolateral and ventromesial distal angles on pereiopod 2, coxae almost inconspicuous; pereiopods 2 and 3 with the dactylus ventral margin furnished with fewer anteriorly directed corneus spines (about 20); pereiopod 4 with only five corneus teeth in the dactylus ventrolateral row; and telson with nine thinner marginal teeth on each lobe ( Fig. 9 D). Females show paired gonopores ( Fig. 12 A); first pleopods paired, uniramous; second to fifth pleopods unpaired, second to fourth with both rami well developed, exopods much longer than endopods and fifth pleopod shorter, with the exopod well developed and a vestigial endopod. Brood pouch moderately large, subtriangular, with smooth margins furnished with long plumose setae ( Fig. 12 B).

Etymology. Devoted to Candela, the daughter of the first author.

Remarks. To date 18 species have been assigned to Paguristes in West Africa, seven of which were transferred to Areopaguristes ( Rahayu 2005, present work) and one to Pseudopaguristes (present work). The type material of the other ten species must be checked in order to clarify their taxonomic status, as suggested by McLaughlin (2002) and Rahayu (2005).

There are no indications of the gill number in the other ten Paguristes species in the literature, but P. candelae n. sp can be clearly differentiated by other features, including the multidentate ocular acicles (more than 3 spines) of Paguristes fagei Forest, 1952 , Paguristes insularis Forest, 1966 , Paguristes microphthalmus Forest, 1952 , Paguristes oxyacanthus Forest, 1952 and Paguristes skoogi Odhner, 1923 ; the relative length of the rostrum, the antennal acicle and the antennal peduncle, as well as the morphology of chelipeds, and pereiopods 2 and 3 of the species Paguristes agulhasensis Forest, 1954a , Paguristes barnardi Forest, 1954a , Paguristes gamianus (H. Milne-Edwards, 1836) , Paguristes macrotrichus Forest, 1954a and Paguristes rubropictus A. Milne-Edwards & Bouvier, 1892 . Moreover, the presence of two gonopods in females was only described for P. gamianus and P. rubropictus , although this detail is unknown for P. agulhasensis (only one male was ever reported) and for P. barnardi , P. macrotrichus and P. skoogi because this feature was never specified; in the other species, females have only one gonopore on left third pereiopod.

Paguristes eremita (Linnaeus, 1767) , Paguristes streaensis Pastore, 1984 and Paguristes syrtensis de Saint Laurent, 1971, also reported from E Atlantic and the Mediterranean Sea, have a rostrum that exceeds the lateral projections and granular chelipeds, whereas in Paguristes candelae n. sp. the rostrum falls short of the lateral projections and the chelipeds have strong corneus-tipped spines.

We also checked the descriptions of the 31 species currently referred to as Paguristes sensu lato from the western Atlantic Ocean ( A. Milne-Edwards 1880; A. Milne-Edwards & Bouvier 1893; Benedict 1901; Schmitt 1933; Forest 1954b; Holthuis 1959; Provenzano 1965; McLaughlin & Provenzano Jr. 1974, 1975; Campos & Sánchez 1995; Sandberg, 1996; Manjón-Cabeza et al. 2002); none of them concurred with the above-mentioned combination of features observed in our specimen, related to the rostrum, antennal acicles, cheliped morphology and telson armature.

Figures

FIGURE 7. Paguristes candelae n. sp. Holotype male (MNCN 20.04 / 9822): A, general, right view. B, general, left view. C, general, frontal view. D, general, ventral view. Scale: A – B, 1 mm; C – D, 5 mm.

FIGURE 8. Paguristes candelae n. sp. Holotype male (MNCN 20.04 / 9822): A, shield and cephalic appendages. B, cephalic appendages, detail. Scale: A – B, 1 mm.

FIGURE 9. Paguristes candelae n. sp. Paratype female (MNCN 20.04 / 9823): A, general, frontal view. B, cephalic appendages, detail. C, chelipeds, dorsal view. D, pleomere 6 and telson, dorsal view. Scale: A – D, 1 mm.

FIGURE 10. Paguristes candelae n. sp. Holotype male (MNCN 20.04 / 9822): A, right cheliped dorsal. B, left cheliped lateroventral. C, left P 2 (top) and P 3 (bottom) mesial view. D, maxilliped 3 ventral view. E, right P 4 carpus to dactylus lateral view. F right P 5 propodus and dactylus, lateral view. Scale: A, D – F, 1 mm; B – C, 5 mm.

FIGURE 11. Paguristes candelae n. sp. Holotype male (MNCN 20.04 / 9822): A, Plp 1, Plp 2 ventral view. B, Plp 1, Plp 2 ventrolatera view. C, Plp 1 lateral view. D, Plp 2 lateral view. E, telson. Scale 1 mm.

FIGURE 12. Paguristes candelae n. sp. Paratype female (MNCN 20.04 / 9823): A, general, ventral view. B, brood pouch and plp 4, detail. Scale 1 mm.