Paguristes haigae, Parente, Manuel Ayón & Hendrickx, Michel E., 2007

Parente, Manuel Ayón & Hendrickx, Michel E., 2007, A new species of Paguristes Dana, 1851 (Anomura, Paguroidea, Diogenidae) from the Mexican Pacific, Zootaxa 1470, pp. 59-68 : 60-67

Paguristes haigae n. sp.

( Figs 1–3 )

Paguristes bakeri .— Hendrickx, 1994: 31 (in part, one large male from off Cabo San Miguel, ex EMU-232A, herein designated a paratype of P. haigae n. sp.).

Type material. Mexican Pacific. Holotype female (SL, 5.3 mm), GUAYTEC II, stn 4, Gulf of California, 26°47’N, 110°06’W, 85 m, trawl, 1 Aug 1987, EMU-7149. Paratypes: GUAYTEC I, stn 16, Gulf of California, 29º30.9’N, 113º24.5’W, 95–115 m, trawl, 17 Feb 1987, 1 male (SL, 3.2 mm), EMU-7268; CORTES 3, stn 21, off Cabo San Miguel, Lower California, Gulf of California, Mexico, 28º9’N, 112º42’W, 112 m, trawl, 1 Aug 1985, 1 male (SL, 8.9 mm), EMU-7150 (ex EMU-232A).

Description. Thirteen pairs of biserial gills; branchiostegites each with few spinules on distal margin and dorsal margin, concealed by moderately dense long setae. Shield ( Fig. 1 A) longer than broad; dorsal surface almost smooth with some spines and spinules on lateral surface and scattered tufts of long setae. Rostrum terminally blunt, tip with marginal setae, reaching beyond base of ocular acicles and slightly overreaching lateral projections. Lateral projections triangular, each with small terminal spine.

Ocular peduncle 0.63–0.67 length of shield, slender, dorsomesial surface with row of short setae; corneal diameter 0.20–0.23 peduncular length. Ocular acicle wide basally, subtriangular or subquadrate, ending in simple or bifid spine, lateral margin unarmed, acicles separated by space approximately 0.50–0.70 basal width of one acicle.

Antennular peduncle ( Fig. 1 A, B) moderately long, when fully extended equal to ocular peduncle or exceeding by 0.25 length of ultimate segment. Ultimate segment unarmed; penultimate segment with small spine on ventromesial margin in proximal half; basal segment with moderately strong spine on ventrodistal margin, mesial and lateral surfaces each with strong spine on distal margin, small spine on lateral face of statocyst lobe.

Antennal peduncle moderately long, reaching 0.67–0.70 length of ocular peduncle; fifth segment with few scattered tufts of setae; fourth segment with strong spine dorsodistal; third segment with ventral margin strongly produced, ending in strong spine; second segment with dorsolateral distal angle produced, ending in bifid spine, lateral margin with 2 or 3 strong spines, 1 smaller spine on distal third of dorsolateral surface, dorsomesial angle with 1 strong spine, mesial margin with 1 or 2 moderately strong spines and tufts of setae; first segment with 1 laterodistal spine, ventral margin strongly produced, rounded. Antennal acicle moderately long, reaching to distal margin of fifth peduncular segment, terminating in prominent bifid spine; ventrolateral margin with 1 small spine, 1 or 3 spines on dorsolateral margin, 3 to 4 spines on mesial margin and tufts of setae concealing partially armature. Antennal flagellum as long as shield; articles each with short setae (shorter than 1 article length) on proximal half, distal half with 2 long setae (longer than 2 articles length) and several setae (shorter than 1 article length).

Mandible without distinguishing characters.

Maxillule ( Fig. 3 A) with proximal (coxal) endite subquadrate, distal (basial) endite subrectangular, enlarged distally, with rigid setae on internal margin; endopod with 1 proximal seta and 2 to 4 terminal bristles on weakly produced internal lobule, external lobule well developed, recurved, approximately 0.67 length of endopod, outer angle with 2 long plumose setae.

Maxilla ( Fig. 3 B, C) with endopod moderately long, proximal half somewhat inflated, slightly exceeding scaphognathite in distal extension; proximal and distal lobes of coxal endite with setae.

First maxilliped ( Fig. 3 D) with endopod shorter than basial segment of exopod, epipod well developed.

Second maxilliped ( Fig. 3 E) with basis-ischium fusion incomplete.

Third maxilliped ( Fig. 3 F) with basis-ischium fusion incomplete; basis with 2 to 4 small spines on ventral margin; ischium with crista dentata well developed, with 13 to 20 corneous denticles, without accessory tooth, with 1 small spine at dorsodistal and ventrodistal angles; merus with 3 to 4 spines on ventral margin, dorsodistal margin with 1 small spine; carpus with 1 small spine at dorsodistal and ventrolaterodistal margins.

Chelipeds equal, similar, short and tomentose ( Fig. 1 C, D). Dactyl 1.50 longer than palm, ending in moderately strong, spoon-shaped claw; dorsomesial margin with row of strong, corneous-tipped spines, decreasing in size distally, and tufts of stiff plumose setae; lateral margin with row of moderately strong, corneoustipped spines accompanied with tufts of setae; dorsal surface with 2 rows of small tipped spines accompanied with tufts of setae; mesial face ( Fig. 1 D) and ventromesial margin with moderately strong granules or corneous-tipped spines accompanied with tufts of stiff setae or bristles; ventral face each with few tufts of stiff setae or bristles; cutting edge with row of calcareous (proximally) and corneous (distally) teeth. Palm moderately long, about 0.50 length of carpus; dorsomesial margin each with 4 strong, corneous-tipped spines, the 2 proximal closely set; dorsolateral margins each with row of corneous-tipped spines decreasing in size proximally and distally; dorsal surface with 4 irregular rows of corneous-tipped spines accompanied with moderately long plumose setae; mesial, lateral and ventral faces with few moderately strong, corneous-tipped spines accompanied with tufts of long stiff setae. Fixed finger ending in moderately strong spoon-shape claw; a few corneous-tipped spines and tufts of stiff setae on dorsal face; inner proximal edge with some small corneous teeth; cutting edge with moderately strong calcareous teeth proximally and corneous teeth distally. Carpus moderately short, approximately 0.70 length of merus; dorsomesial margin with 4 strong, corneous-tipped spines accompanied with tufts of long rigid setae; dorsolateral margin with 6 or 7 strong or moderately strong, corneous-tipped spines; dorsal face with few strong or moderately strong spines and tufts of setae; mesial and outer faces with few small granules ending in spines or corneous-tipped spines, and tufts of stiff setae; ventrolateral angle with one small tipped spine; ventral surface unarmed. Merus subtriangular; dorsal face with 1 row of small tipped spines increasing in size distally and forming transversal rows of strong or moderately strong tipped spines accompanied with tufts of long plumose setae, subdistal and distal margins each with strong or moderately strong corneous-tipped spines extending on lateral and mesial margins; mesial face smooth; outer face with spinules or small spines; ventromesial and ventrolateral margins each with row of small spines increasing in size distally; ventral face with scattered spinules distally. Ischium with row of small spines on ventromesial margin. Coxa with 1 small spine at ventrodistal margin, concealed by tufts of long, plumose setae.

Pereopods 2 and 3 similar ( Fig. 2 A–D), left slightly longer than right, differing somewhat in armature, tomentose ventrally and dorsally. Dactyl 1.50–1.62 longer than propodus; dorsal surface with tufts of moderately long plumose setae on proximal fourth, remainder with tufts of long, moderately stiff setae; dorsomesial margin with row of prominent, corneous-tipped conical or tubular spines proximally, forming row of corneous spines distally, partially concealed by dense tufts of long plumose setae; lateral and mesial faces each with tufts of moderately long setae; ventromesial and ventrolateral margins each with row of small corneous-tipped spines and long plumose setae; ventral margin with 15–17 corneous spines, concealed by long, plumose setae. Propodus moderately short, 1.08–1.12 length of carpus; dorsal surface with row of prominent corneous-tipped spines (pereopod 2) and smaller spines (pereopod 3), partially obscured by tufts of moderately stiff long setae; mesial, lateral and ventral faces each with rows of small, corneous-tipped spines partially obscured by tufts of plumose setae (pereopod 2); mesial and ventral faces of pereopod 3 each with rows of small corneous-tipped spines partially obscured by tufts of plumose setae; lateral face with longitudinal row of tufts of plumose setae (pereopod 3). Carpus moderately long, 0.75–0.78 (pereopod 2) and 0.85–0.90 (pereopod 3) length of merus; dorsal surface with 2 longitudinal irregular rows of moderately strong or strong spines, mesial spines longer than lateral (pereopod 2), or with one row of spines increasing in size distally (pereopod 3); mesial face smooth; lateral face with few spinules and tufts of setae, 1 moderately strong spine on the middle laterodistal margin (pereopod 2); ventral face with tufts of long plumose setae on distal margin (pereopod 2); lateral face with 1 longitudinal sulcus flanked by tufts of plumose setae (pereopod 3); lateroventral margin and ventral surface each with tufts of plumose setae (pereopod 3). Merus compressed laterally; dorsal face with row of spinules or small spines obscured partially by tufts of long plumose setae (pereopod 2) and 1 moderately strong spine distally (pereopod 3); mesial face smooth with scattered tufts of very short setae; lateral face with few spinules and tufts of short setae, ventrolateral angle with 1 moderately strong spine and tufts of long plumose setae; ventral surface with double row (pereopod 2) or simple row (pereopod 3) of small corneoustipped spines and tufts of long plumose setae. Ischium with row of small spines on ventromesial margin (pereopod 2); dorsodistal margin with 2 small spines partially obscured by tufts of plumose setae (pereopod 2); dorsal face and laterodistal margin with small spines or spinules and tufts of long plumose setae (pereopod 3). Pereopod 4 ( Fig. 2 E) with propodal rasp well developed, with 3 or 4 rows of ovate scales; dactyl moderately long, with 4 or 5 corneous spines posterior to claw; preungual process present; 1 dorsodistal spine on carpus. Sternite XII (pereopods 3) ( Fig. 2 F) subrectangular; a middle lobule with tufts of long setae.

Male gonopod 1 ( Fig. 1 E, F) with tuft of setae on superior mesial angle of basal lobe, mesial margin of basal lobe with 1 seta; single row of small hook-like corneous spines on distal margin of inferior lamella; external lobe conical, overreaching inferior lamella, internal lobe short, rounded, with marginal setae and some few short setae on inner and external surfaces. Gonopod 2 ( Fig. 1 G) with basal segment usually naked; endopod with 2 moderately long, plumose setae on mesial margin, distal angle with 1 (small male paratype) or tuft of stiff setae (large male paratype); appendix masculina with long setae on distal margin and inferior surface.

Left pleopods 3–5 with exopod well developed; endopod rudimentary. Female pleopod 1 ( Fig. 2 G) basial segment with few moderately long marginal setae; distal segment with long marginal setae. Brood pouch ( Fig. 2 H) subrectangular, large and provided with fringe of plumose setae.

Telson ( Fig. 1 H) with posterior lobes subcircular, asymmetrical, left larger than right; separated by small, median, shallow cleft; posterior margin of lobes armed with 5 or 6 (right) or 5–7 (left) strong, corneous-tipped spines; lateral margins each with 2 or 3 corneous-tipped spines (left stronger than right) and tufts of long setae; anterior lobes with 2–4 strong or moderately strong, marginal corneous-tipped spines and tufts of long setae.

Color. Specimens fixed over a long period of time. Anterior portion of carapace, ocular peduncles, chelipeds and pereopods showing an orange-reddish coloration; cornea dark-brown or black; antennal acicle, antennal peduncle, antenal flagella and antennular peduncle transparent.

Habitat. The three specimens were collected on fine sand sediment in empty shells of Chicoreus erythrostomus (Swainson, 1831) (paratypes) and Haustellum elenensis (Dall, 1909) (holotype).

Distribution. Presently known from the central Gulf of California, Mexico; 85 to 115 m.

Etymology. The species is named in honour of the late Janet Haig for her great contribution to our knowledge of hermit crabs.

Variation. The large male differs from the female holotype and the smaller male in the armature of the ocular acicles (4 spines versus 2 and 1 spines in female and small male, respectively); the armature on dorsal surface of cheliped palm of the larger male also has smaller spines visible among longitudinal rows of strong spines. The small paratype male features five spines on the mesial margin of the carpus of left cheliped, versus four in the holotype and large paratype.

Remarks. Paguristes haigae n. sp. is the first species of the genus described from the tropical eastern Pacific since Glassell (1937, 1938) added six new species to the regional fauna of hermit crabs. Material belonging to Paguristes was briefly described (as Paguristes sp.) by Westervelt (1967: 75, key), Haig et al. (1970: 19), and Ramírez-Guillén (1983: 72, fig. 20). One of the specimens seen by Haig et al. (1970) had been previously reported by Schmitt (1939: 9) from a black sea bass stomach. The specimens reported by Westervelt (1967) from Bahía Cholla area and by Ramírez-Guillén (1983) from Bahía Concepción most probably belong to the same species; the material reported by Haig et al. (1970), while collected from the outer coast of Baja California, might also belong to this species because of the similarities in the color pattern. Comparison of P. haigae n. sp. with the short descriptions provided by Westervelt (1967), Haig et al. (1970), and with the illustration provided by Ramírez-Guillén (1983), however, indicates that our material belongs to a different species (i.e., color pattern very distinct; shape of the rostrum, size and shape of the ocular and antennal acicles, fingertips of claws different).

Paguristes haigae n. sp. was compared with five other species of the genus occurring in the East Pacific that resemble the new species ( Table 1 ). Glassell (1937) described Paguristes aztatlanensis and P. oculiviolaceous without providing illustrations. According to Glassell’s descriptions, both species are close to P. h a i g a e n. sp., yet differ from the latter by several characters. Paguristes aztatlanensis features a proportionally much longer shield than P. haigae n. sp., an acute rostrum, longer than in P. haigae n. sp., and its ocular peduncle is proportionally shorter than in the new species; chelipeds have a very similar armature. However, in P. a z t a t - lanensis the number of spines on the mesial margin of carpus and palm is 4 and 3 respectively, versus 4 and 4 in P. h a i g a e n. sp.; when compared to cheliped length, pereopods 2 and 3 are proportionally longer in P. a z t a t - lanensis than in P. h a i g a e n. sp.; the third maxilliped of P. haigae n. sp. is armed rather than unarmed as in P. aztatlanensis . The antennule in P. oculiviolaceous overreaches the ocular peduncle by half of its length, in lieu of equal or slightly exceeding it as in P. haigae n. sp., and the armature of the carpus of chelipeds varies in these two species ( Table 1 ).

Paguristes haigae n. sp. shows some resemblance to P. bakeri Holmes, 1900 . The telson of P. bakeri , however, has the anterior lobules of telson unarmed rather than armed with 2–4 spines in P. h a i g a e n. sp. In P. haigae n. sp. the rostrum length exceeds the lateral teeth (equal in length in P. bakeri , and often ending in a small spine). In P. haigae n. sp. the armature on the cheliped palms is similar but the spines are not as strong and the setae are not bristle-like and as strong as in P. bakeri . Moreover, the cheliped hand is slender in P. haigae n. sp. The armature of the mesial surface of the cheliped dactyls also differs in these two species ( Table 1 ).

Paguristes haigae n. sp. also resembles P. h o l m e s i Glassell, 1937, a species until recently considered a junior synonym of P. bakeri . Hendrickx & Harvey (1999) briefly discussed the status of P. h o l m e s i. Although she did not publish any information on this issue, it appears that Janet Haig reviewed fresh material from Costa Rica and concluded that P. h o l m e s i had to be re-established as a valid species. While examining the material of Paguristes in the reference collection of Benthic Invertebrate in the Laboratorio de Invertebrados Bentónicos, we found more evidence to confirm this. Several specimens are very close to, yet do not correspond to P. bakeri and agree with several features provided by Glassell (1937) in the original description of P. holmesi . These include: chelipeds subequal (right slightly longer) in Paguristes holmesi , in lieu of chelipeds equal in P. bakeri ; cheliped hands in P. b a k e r i slightly wider than in P. holmesi ; in P. h o l m e s i only the upper margin of the dactyls of pereopods 2 and 3 is spiny, while in P. bakeri both upper and lower margins have closely-set spines.

The telson of P. holmesi has the anterior lobules of telson unarmed instead of bearing 2–4 spines in P. haigae n. sp. Paguristes haigae n. sp. and P. holmesi have similar armature and contour of the cheliped hands, though the spines are stronger in P. holmesi . In P. h o l m e s i the rostral tooth scarcely reaches the base of ocular acicles, which are armed with about 8 teeth, in lieu of 1 or 2 teeth as in P. haigae n. sp. The number of spines on the mesial margin of the carpus of the chelipeds is also different; 5 in P. holmesi (a total of> 60 specimens were examined) versus 4 in P. h a i g a e n. sp. .

P. haigae n. sp. P. anahuacus Glassell, 1938 P. oculiviolaceous Glassell, 1937 Table 1 , continued.

Paguristes haigae n. sp. also resembles P. tortugae Schmitt, 1933 , from the western Atlantic. The rostrum and ocular acicles are similar, but they differ by the cheliped armature and the shape of the brood pouch in females.

Setae on the coxal endite of maxilla of the holotype of P. h a i g a e n. sp. present a terminal capsule (see Fig. 3 C) which might correspond to protozoan infection. McLaughlin (2002) erected the genus Pseudopaguristes for Pseudopaguristes janetkae McLaughlin, 2002 , which is characterized by having eight pairs of phyllobranchiate gills, noting ( McLaughlin 2002: 190, 193) that the carpus of the fourth pereopods had thick tuft of strangely capsulate setae on ventral margin; the capsulate setae of P. haigae , however, are of a different type.

Figures

FIGURE 1. Paguristes haigae n. sp., Gulf of California. A – D, H, holotype female (SL 5.3 mm) (EMU- 7149); E – G, male paratype (SL 3.2 mm) (EMU- 7268). A, shield and cephalic appendages; B, left antennule (external view); C, chela and carpus of right cheliped (dorsal view); D, right cheliped (mesial view; setae omitted); E, left first pleopod (external view); F, left first pleopod (internal view); G, left second pleopod (internal view); H, telson. Scales bars: A, C – D 2.0 mm; B, H 1.0 mm; E – G 0.5 mm.

FIGURE 2. Paguristes haigae n. sp., Gulf of California, holotype female (SL 5.3 mm) (EMU- 7149). A, right second pereopod (mesial view); B, right second pereopod (lateral view); C, right third pereopod (mesial view); D, right third pereopod (lateral view); E, left fourth pereopod (lateral view); F, plate on sternite XII (third pereopods); G, left first pleopod (internal view); H, female brood pouch. Scales bars: A – E 2.0 mm; F, H 1.0 mm; G 0.5 mm.

FIGURE 3. Paguristes haigae n. sp. Gulf of California, holotype female (SL 5.3 mm) (EMU- 7149). A, left maxillule (inner view); B, left maxilla (inner view); C, distal lobe of coxal endite of maxilla (inner view); D, left first maxilliped (inner view); E, left second maxilliped (inner view); F, left third maxilliped (inner view). Scales bars equal: C 0.25 mm; A, B, D – F 0.5 mm.

Tables

TABLE 1. Comparison of some morphological characters in selected species of Paguristes. Species used for comparison were selected according to their resemblance to P. haigae n. sp. Data obtained from original descriptions. An asterisk (*) indicates additional features observed on fresh material. ND, no data. R, right. L, left.

Rostrum	Blunt triangular, slightly exceeding base of ocular aci- cles	Long, sharp-pointed, apex extending slightly past centre of ocular acicle	Equilateral, reaching well between ocular acicles
Ocular peduncle	Passing merus of cheliped by approximately 1/6.	Reaching distal margin of merus of cheliped	Extending to subdistal margin of merus of cheliped
Ocular acicles	Ending in 1 or 2 spines	Bifid, toothed on outer mar- gin	Bifid tip
Antenular peduncle	Equal or exceeding by ¼ ocular peduncle	As long as ocular peduncle	One and ½ as long as ocular peduncle
Antennal acicle	3 or 4 spines on the mesial margin; outer margin with 1– 3 spines	One proximal inner single sharp-pointed tooth; outer margin with 1 or 2 teeth at distal 1/3	Inner margin with 4 sharp teeth; outer margin with 1
Flagellum	Slightly ciliated. Reaching proximal end of hand	Slightly ciliate. Passing mid- dle of carpus	Reaching proximal end of hand
Chelipeds	Equal,similar	Subequal	Subequal,similar
Carpus of chelipeds	Inner margin with 4 spines; outer margin with 6 spines	Inner margin with 5 cor- neous-tipped, conical spines; outer margin with 8 or more smaller spines	Inner margin with 5 corneoustipped spines; outer margin outlined with still smaller spines
Hand of chelipeds	Inner margin with 4 spines	Inner margin with 3 spines	Inner margin with 4 spines, proximal two having a common base
Pereopods (2 and 3)	Stout, exceeding chelipeds by ½ dactylus length	Stout; passing chelipeds by length of their dactylus	Slender, exceeding length of cheliped by ½ their dactyli; dactyli nearly as long as carpus and propodus combined
3rd maxilliped	Merus with 3 or 4 spines on ventral margin	Merus with 3 spines on ven- tral margin	ND
Shield length/width	1.19–1.20	1.35–1.48	1.17
Telson	Posterior lobules subcircular. Distal margin with 5 or 6 (R) and 5–7 (L) corneous spines; lateral margins armed with 2-3 spines. Anterior lobules armed with 2-4 spines	Distal end broadly V-shaped, armed with 5–7 corneous spines (R, L); lateral margins unarmed. Anterior lobules armed with 1-3 spines *	“Distal margin margined with cor- neous-tipped spines” [sic]
Ocular peduncle length/shield length	0.63–0.67	0.48	0.66
Mesial surface of dactyl of cheliped	Two irregular longitudinal rows of small corneous spines (upper row usually bifid spines)	Two longitudinal rows of simple, small corneous spines *	ND