Areopaguristes tudgei, Lemaitre, Rafael & Felder, Darryl L., 2012

Lemaitre, Rafael & Felder, Darryl L., 2012, A new species of the hermit crab genus Areopaguriste s Rahayu & McLaughlin, 2010 (Crustacea: Decapoda: Anomura: Diogenidae) discovered in the Mesoamerican Barrier Reef of Belize, Caribbean Sea, Zootaxa 3480, pp. 67-79 : 68-76

Areopaguristes tudgei n. sp.

( Figs. 1–6 )

Material examined. Holotype: ♂ 2.5 mm, Carrie Bow Cay, Belize, 16°48’N, 88°05’W, front reef crest (E side of island), under rocks, intertidal, February 5, 2011, colls. C. Tudge, D. Felder, J. Felder, R. Lemaitre, and S. Pecnick ( USNM 1156990). Paratypes, all same locality and year as holotype, February 4, 2 ♂ 1.9, 2.1 mm, 8 ♀ 1.5–2.1 mm ( USNM 1156991); 2 ♀, 1.9 (color voucher), 2.1 mm ( ULLZ 12530); 2 ♂ 2.9, 3.0 (color voucher), 1 ♀ 2.6 mm ( ULLZ 12576); February 5, 10 ♂ 1.0– 2.7 mm, 33 ♀ 1.0– 2.1 mm, 1 ovig. ♀ 2.0 mm ( USNM 1156992); February 8, 9 ♂ 1.6–2.7 mm, 9 ♀ 1.4–1.8 mm, 8 ovig. ♀ 1.5–2.5 mm ( USNM 1156993).

Diagnosis. Gills biserial. Shield unarmed or at most with few minute spines on anterodorsal margins. Ocular peduncles about half length of shield, decreasing in width distally. Chelipeds with dorsal surfaces of chelae and carpi densely covered with plumose setae obscuring armature beneath. Second and third pereopods with dense fringe of plumose setae on dorsal margins of meri, carpi, propodi and dactyls. Telson with terminal margins oblique, setose, each side with 1–5 small to minute, blunt to sharp calcareous spines. Male first pleopod with distal margins of external lobe and inferior lamella entire, lacking spines, teeth or setae. Female lacking brood pouch. Color as in description.

Description. Gills biserial. Shield ( Fig. 1 a) subtriangular, about 1.2 times as long as broad, posterior margin about 0.3 shield width; dorsal surface weakly convex, generally smooth or at most with few minute spines on anterior dorsolateral margins, with plumose setae lateromedially and scattered short setae elsewhere; ventrolateral margin with minute spine distally. Anterolateral margins sloping. Anterior margins between rostrum and lateral projections concave. Lateral projections triangular, ending in small sharp or blunt spine. Rostrum narrowly triangular, often slender ( Fig. 1 a, b), extending distinctly beyond lateral projections, ending in rounded tip with several setae. Ocular peduncles (including corneas) about half length of shield, decreasing in width distally, with plumose setae dorsally; corneas slightly dilated; ocular acicles subtriangular, separated by rostrum, each ending in sharp spine and with 1–3 additional spines on oblique lateral margin.

P. angustitheca McLaughlin & Provenzano, 1974 * P. anomalus Bouvier, 1918 (= P. anaryballus Provenzano, 1965 )* P. cadenati Forest, 1954

P. depressus Stimpson, 1859 [= P. depressus Stimpson, 1858 (nomen nudum)] P. erythrops Holthuis, 1959

P. g r a y i Benedict, 1901

P. hernancortezi McLaughlin & Provenzano, 1974 * P. holguinensis Manjón-Cabeza, García Raso & Martínez Iglesias, 2002 P. inconstans McLaughlin & Provenzano, 1975 P. lapillatus McLaughlin & Provenzano, 1975

P. laticlavus McLaughlin & Provenzano, 1975

P. limonensis McLaughlin & Provenzano, 1975 P. l y m a n i A. Milne-Edwards & Bouvier, 1893

P. maclaughlinae Martínez-Iglesias & Gómez, 1989 * P. markhami Sandberg, 1996

P. m o o re i Benedict, 1901

P. oxyophthalmus Holthuis, 1959

P. paraguanensis McLaughlin & Provenzano, 1975 P. pauciparus Forest & de Saint Laurent, 1968

P. perplexus McLaughlin & Provenzano, 1974 * P. planatus A. Milne-Edwards & Bouvier, 1893 P. puncticeps Benedict, 1901

P. robustus Forest & de Saint Laurent, 1968

P. s a y i A. Milne-Edwards & Bouvier, 1893

P. sericeus A. Milne Edwards, 1880 (= P. rectifrons Benedict, 1901 ; = P. tenuirostris Benedict, 1901 P. spectabilis McLaughlin & Provenzano, 1975 P. spinipes A. Milne-Edwards, 1880 (= P. a r m a t u s Hay, 1917; = P. visor Henderson, 1888 ) P. starcki Provenzano, 1965

P. tortugae Schmitt, 1933 *

P. triangulopsis Forest & de Saint Laurent, 1968 P. triangulatus A. Milne-Edwards & Bouvier, 1893 P. wassi Provenzano, 1961

P. w e rd i n g i Campos & Sánchez, 1995 *

P. z e b r a Campos & Sánchez, 1995 *

Areopaguristes Rahayu & McLaughlin, 2010

A. hewatti ( Wass, 1963) *

A. hummi ( Wass, 1955)

A. iris (Forest & de Saint Laurent, 1968)

A. tudgei n. sp.

Pseudopaguristes McLaughlin, 2002

P. calliopsis (Forest & de Saint Laurent, 1968)

P. invisisacculus ( McLaughlin & Provenzano, 1974) *

Antennular peduncles ( Fig. 1 a) slightly exceeding distal margins of corneas. Ultimate and penultimate segments subequal in length. Basal segment with spine on dorsolateral margin of statocyst lobe.

Antennal peduncles ( Fig. 1 a) exceeding distal margin of corneas by about 0.2 length of fifth segment. Fourth segment with small dorsodistal spine. Third segment ventrodistal margin prominently produced and terminating in strong, acute spine. Second segment with plumose setae dorsally; with dorsolateral distal angle produced, terminating in simple or bifid spine and with 1–3 spines on lateral margin. First segment unarmed or sometimes with minute spine on distolateral angle. Antennal acicles reaching at most to about midportion of corneas, terminating in strong simple to bifid spine; mesial margin with 1–4 spines, lateral margin with 2–4 spines. Flagellum short, about as long as shield; all articles with short setae <1 article in length.

Mandible ( Fig. 2 a) with upper and lower incisor edges calcareous; ultimate segment of palp broad, setose, nearly as long as combined length of penultimate and basal segments. Maxillule ( Fig. 2 b) with proximal endite subquadrate; endopod with 2 or 3 long setae on weakly developed internal lobe, external lobe elongate, about half as long as endopod, and curving proximally. Maxilla ( Fig. 2 c) with endopod extending to distal end of scaphognathite, tapered distally. First maxilliped ( Fig. 2 d) with endopod about 0.75 length of exopod, setose distally. Second maxilliped ( Fig. 2 e) without distinctive characters. Third maxilliped ( Fig. 2 f, g) with well developed crista dentata on ischium and without accessory tooth.

Chelipeds ( Fig. 3 a–f) subequal, or left slightly larger than right, similarly armed; dorsal surfaces of chelae and carpi densely covered with tufts of plumose setae obscuring armature beneath, setae evenly present or more dense and long on dorsolateral margins of chelae, setation generally denser in males than in females. Fingers and palms with dorsal surfaces covered with irregularly placed small spines or tubercles; cutting edge of fingers each with several small calcareous teeth on proximal 0.7, and with row of fused corneous teeth forming hoof-like claw distally ( Fig. 3 c). Dactyl about 1.4 times as long as palm. Palms with dorsal surfaces evenly convex; each with 3 strong, corneous-tipped spines on dorsomesial margin; lateral and mesial margins rounded, unarmed or with scattered small tubercles; ventral faces mostly unarmed or with scattered small tubercles and few ventrolateral plumose setae. Carpi with dorsal surfaces with well-spaced small spines or tubercles; dorsomesial margins each with 4 or 5 corneous-tipped spines (proximal 2 spines small), dorsolateral margins with regular or irregular rows of small spines; lateral, mesial, and ventral faces unarmed or with scattered small tubercles and setae. Meri long, about 1.7 times as long as carpi, subtriangular in crossection; dorsal margins with plumose setae; lateral and mesial faces unarmed except for transverse row of minute blunt spines subdistally on each face; ventrolateral and ventromesial margins each with row of spines (smaller on ventrolateral margins); ventral faces with plumose setae. Ischia unarmed except for few setae on ventromesial margins.

Second and third pereopods ( Fig. 4 a–e) generally similar except left slightly shorter than right; dorsal margins of meri, carpi, propodi and dactyls with dense fringe of plumose setae. Dactyls about same length as propodi, terminating in sharp corneous claw; ventromesial margin armed with 9–11 corneous spinules in addition to long subdistal bristle near base of claw; ventral margins with well-spaced plumose setae. Propodi each with dorsomesial row of small spines; dorsolateral faces with short low ridges and with scattered plumose setae; ventromesial faces each with short, transverse rows of small spines. Carpi each with dorsal row of spines; dorsolateral face with dense plumose setae, and short low ridges; dorsomesial face with irregular rows of small spines. Meri each with plumose setae on ventral margin and ventromesial distal row of small spines. Anterior portion of sternite XII ( Fig. 5 ) with transverse, setose ridge slightly elevated at midline.

Fourth pereopods ( Fig. 4 f) with propodi distinctly longer than high, or infrequently in some large males (≥ 2.0 mm) about as long as high; propodal rasp extending about 0.7 distal length of segment, with 2 or 3 rows of ovate corneous scales distally, and 1 row proximally. Fifth pereopods ( Fig. 4 g) chelate; propodal rasp extending for about 0.3 length of segment.

Male with paired first and second pleopods modified as gonopods, and unpaired left second to fifth; first pleopod ( Fig. 1 c) with long setae on mesial margin of internal lobe, distal margins of external lobe and inferior lamella entire, lacking spines, teeth or setae; second pleopod ( Fig. 1 d) with basal segment naked except for occasional few distal setae, distal segment with setose margins; third to fifth pleopods ( Fig. 1 e) with vestigial endopods. Female with paired gonopods, paired first pleopods ( Fig. 1 f), and unpaired left second to fifth ( Fig. 1 g), lacking brood pouch; first pleopod with naked basal segment, and distal segment with long, marginal bristle-like setae; number of eggs ranging 8–21 (n = 10), relatively large (~ 0.7 mm in maximum width).

Telson and uropods ( Fig. 1 h, i) asymmetrical. Telson with distinct, deep lateral incisions dividing anterior and posterior portions; anterior lobes with long setae on posterolateral angles; posterior lobes separated by shallow median cleft; terminal margins oblique, setose, each with 1–5 small to minute, blunt or sharp calcareous spines (larger on left side) often curved ventrally.

Color ( Fig. 6 ). In life, shield whitish or cream color, with 3 brownish-red patches anteriorly (1 directly behind each anterolateral projection, and 1 behind the rostrum). Posterior carapace semitransparent; anterolateral corner with distinct pink patch. Ocular peduncles whitish except for short distal faint, dorsomesial brown stripe; distally semitransparent. Ocular scales whitish. Antennules whitish except for light blue distal segment and flagella. Antennal acicles whitish except for acicle distally brownish, and flagella light blue. Chelipeds with dorsal surfaces of carpi and chelae brownish except for whitish distal portion of fingers; meri whitish with dorsodistal surfaces brownish. Walking legs (second and third pereopods) with dactyls brown except for whitish distal portion; carpi, and propodi brownish on entire mesial faces, on dorsal surface and on upper half of lateral faces; meri whitish except for brownish dorsodistal portion. Fourth and fifth pereopods whitish. Pleon with pair of distinct small dark spots anterodorsally near division of thorax and pleon, and several dot-like spots on each side between second and third pleonal somite (spots visible on Fig 6 a only). Female pleon showing dark orange gonads; male pleon whitish or yellowish.

Distribution and habitat. So far known only from Carrie Bow Cay, on the Caribbean Mesoamerican Barrier Reef off the coast of Belize; intertidal under dead coral boulders heavily encrusted with calcareous red and other algae. All specimens were living in gastropod shells.

Etymology. This species is named after our colleague Christopher C. Tudge (American University) who first noticed and collected populations of this diminutive hermit crab living under large dead coral boulders during joint field work in Carrie Bow Cay. The name also acknowledges his unique contributions to knowledge of the reproductive biology of hermit crabs.

Morphological variations. In the 80+ specimens examined, morphological variations are minimal in some characters, such as spination of chelipeds and walking legs. The shield is smooth, usually lacking spines, although rarely a few minute, blunt spines are present on the anterior dorsolateral margin. In other characters, variations are significant or related to sex, such as the shape of the rostrum, degree and pattern of setation on the chelipeds, and the armature of the terminal margins of the telson. The rostrum varies from moderately slender to slender ( Fig. 1 a, b). Setation of the carpi and chelae of both cheliped is denser in males than in females. On the chelae of the latter, a dorsolateral fringe of plumose setae is typically present, whereas in males the plumose setae are not arranged as a fringe and instead are more or less evenly dense throughout the dorsal surface of the chelae ( Fig. 3 a, b). The terminal margins of the telson can be armed on each side with one to five blunt, calcareous spines ( Fig. 1 h), or often with only one minute spine on each laterodistal angle ( Fig. 1 i), or occasionally unarmed except for long setae.

Remarks. As previously mentioned, Areopaguristes tudgei n. sp. might potentially be confused with Paguristes tortugae Schmitt, 1933 , or suspected to represent one of the recognized but as yet undescribed representatives of the P. tortugae complex. McLaughlin & Provenzano (1974) included seven species in this complex, and three more were subsequently added by Martínez-Iglesias & Gómez (1989) and Campos & Sánchez (1995). Of the ten species that have been assigned to the complex ( Table 1), P. hewatti Wass, 1963 is now in Aeropaguristes, and P. invisisacculus McLaughlin & Provenzano, 1974 in Pseudopaguristes McLaughlin, 2002 (see Table 1). As in P. tortugae and members of the complex, A. tudgei n. sp. has dense plumose setation on the chelipeds, and at least in females, there is a fringe of plumose setae on the dorsolateral margins of the chelae. A fringe of setae is also present on the dorsal margins of the walking legs of this new species.

Aside from the fundamental difference in number of gills between Areopaguristes and Paguristes sensu stricto (12 pairs in the former, and 13 in the latter), there are other important differences between A. tudgei n. sp. and species assigned to the P. tortugae complex that should prevent any confusion, such as the armature of the telson (terminal margins with weak blunt spines or unarmed in A. tudgei vs. armed with strong spines in the P. tortugae complex), the male first pleopod (distal margin of inferior lamellae unarmed in A. tudgei vs. armed with small hooked spines in P. tortugae complex), and the presence or absence of brood pouch (absent in A. tudgei vs. present in the P. tortugae complex except P. anomalus Bouvier, 1918 ).

There are marked morphological differences among the four western Atlantic species that have so far been assigned to Areopaguristes , and allow for their clear separation, particularly if specimens of both sexes are available. Areopaguristes hummi ( Wass, 1963) can be immediately differentiated by the adjacent ocular scales and short rostrum, whereas in the other three western Atlantic congeners the ocular scales are separated and the rostrum extends forwardly between the scales. Areopaguristes iris (Forest & de Saint Laurent, 1968) is distinguishable by the slender walking legs, in particular the dactyls which can be 10 times as long as their basal height, whereas in other congeners from the region the dactyls are at most six times as long as high. Areopaguristes hewatti ( Wass, 1963) can be separated by the shape and armature of the chelipeds. In A. hewatti the dorsolateral and dorsomesial margins of the carpi and palm, and the distomedial region of the carpi, are distinctly elevated; and the dorsomedian armature of the carpi and chela consists of many low, mostly blunt spines or tubercles. Also, A. hewatti is the only western Atlantic Areopaguristes species in which females have a brood pouch, although presence or absence of a brood pouch needs to be confirmed for A. iris when females of that species are discovered as A. iris is known exclusively from the type material consisting of four males (male holotype, MNHN Pg 2377, and three male paratypes, MNHN Pg 2378) used by Forest & Saint Laurent (1968). The new species, A. tudgei , is distinguished from all other congeners from the region primarily by the weakly armed or unarmed, terminal margins of the telson ( Fig. 1 i), all others having strong spines; and males having first pleopods with the distal margin of the inferior lamella entire, unarmed ( Fig. 1 c), all others having minute hooked spines. There are also differences in coloration among the four western species of Areopaguristes ; however, a detailed comparison of all four species is not possible because Forest & de Saint Laurent’s (1968: 84) description of coloration in A. iris was very brief, indicating only the presence of iridescence in preserved specimens.

Figures

FIGURE 1. Areopaguristes tudgei n. sp., Carrie Bow Cay, Belize: a, c – e, h, male paratype, 2.1 mm ,, February 8 (USNM 1156993); b, f, g, i, female paratype, 2.1 mm, February 4 (USNM 1156991). a, shield and cephalic appendages, dorsal view; b, anterior portion of shield, dorsal view; c, male left first pleopod, posterior view; d, left second pleopod, posterior view; e, male left third pleopod, posterior view; f, female left first pleopod, posterior view; g, female left third pleopod, posterior view; h, uropods and telson, dorsal view; i, telson, dorsal view. Scales equal 0.5 mm (a, b, e, h, i), 0.2 mm (c, d, f, g).

FIGURE 2. Areopaguristes tudgei n. sp.: male paratype, 2.1 mm, Carrie Bow Cay, Belize, February 8 (USNM 1156993). Left mouthparts, internal view: a, mandible; b, maxillule; c, maxilla; d, first maxilliped; e, second maxilliped; f, third maxilliped, g, ischium of same with crista dentata. Scales equal 0.1 mm (a – d, g), and 0.2 mm (e, f).

FIGURE 3. Areopaguristes tudgei n. sp.: male paratype, 2.1 mm, Carrie Bow Cay, Belize, February 8 (USNM 1156993). Chelipeds, all dorsal view except f (mesial), and c (ventral); a, b, showing approximate density of setation; c – f, with setae omitted. a, d, left; b, e, right; c, fingers of same; f, right. Scale equals 0.5 mm.

FIGURE 4. Areopaguristes tudgei n. sp.: male paratype, 2.1 mm, Carrie Bow Cay, Belize, February 8 (USNM 1156993). a, second right pereopod with plumose setae, lateral view; b, dactyl of same, mesial view; c, same pereopod with setae omitted, mesial view; d, third right pereopod, lateral view; e, dactyl of same; f, propodus and dactyl of right fourth pereopod, lateral view; g, propodus and dactyl of right fifth pereopod, lateral view. Scales equal 0.5 mm.

FIGURE 5. Areopaguristes tudgei n. sp.: male paratype, 2.1 mm, Carrie Bow Cay, Belize, February 8 (USNM 1156993). Sternites XI – XIV, coxae of chelipeds and second to fifth pereopods, and anterior portion of pleon with first and second pleopods, ventral view. Scale equals 0.5 mm.

FIGURE 6. Areopaguristes tudgei n. sp., Carrie Bow Cay, Belize, February 4: a, female paratype 1.9 mm (ULLZ 12530); b, male paratype 3.0 mm (ULLZ 12576). Scales equal 1 mm.