Dardanus sinistripes ( Stimpson, 1859 )

Parente, Manuel Ayón & Hendrickx, Michel E., 2009, 2323, Zootaxa 2323, pp. 1-71 : 5-13

Dardanus sinistripes ( Stimpson, 1859)

( Figs. 1–5, 6A, 13A, 36A–E)

Pagurus sinistripes Stimpson, 1859: 36 .

Dardanus sinistripes 1974 .— Ball & Haig, 1974: 97 (in part, see material examined).

Material examined. Type material. Neotype male (SL 6.05 mm), Taboguilla Island , 8º48.2’N, 79º30.7’W, Panama, Te Vega XVIII-15, 7 May 1968, 7.5 m, scuba, bottom of coarse gravel interspersed with finer material, LACM CR 1968 - 427.1 .

Additional material. 3 males (SL 3.71–5.18 mm), Taboguilla Island , 8º48.2’N, 79º30.7’W, Panama, Te Vega XVIII-15, 7 May 1968, 7.5 m, scuba, bottom of coarse gravel interspersed with finer material, LACM CR 1968 - 427.2 .

Diagnosis. Merus of third maxilliped with 1 or 2 spines on ventral margin. Left cheliped slender. Setae on outer face of palm of left cheliped moderately long, plumose, reaching basis of the next scale. Scales on the palm of left cheliped small to moderately small and subrectangular. Outer lower angle of carpus of left cheliped bearing a rounded spine. Upper face of dactyl of left cheliped with 2 or 3 irregular rows of scale-like tubercles, fringed anteriorly with rounded granules or ending in spine. Outer face of palm of the left cheliped and the lateral face of the left third pereopod dactyl and propodus with moderately long plumose setae. Lateral face of dactyl of left third pereopod with scales interrupted medially by strong, deep, longitudinal grove, and longitudinal scaly ridge below groove, scales fringed with small rounded tubercles or spines and short plumose setae. Corneous-tipped spines present along the entire ventrolateral margin of the left third pereopod dactyl.

Description. Shield ( Fig. 1A, B) slightly longer than broad, or as long as broad; anterior margin between rostrum and lateral projections shallowly concave; lateral margins slightly convex, somewhat irregular, with small spines or tubercles on anterior 1/3 and tufts of long setae. Anterolateral margins unarmed or with few small spines or granules. Dorsal surface of shield flat, with few tufts of long setae; weakly calcified Y-shaped line present posteriorly. Rostral tooth weakly produced. Lateral projections large, bluntly triangular, produced, usually bearing a small spine on distal margin. Posterior carapace lateral elements well calcified, unarmed. Branquiostegites unarmed.

Ocular peduncles ( Fig. 1A) ca 2/3 length of shield, thick, weakly compressed at middle, usually with 7 bristles on the superior notch. Cornea moderately to strongly dilated, 1.35–1.48 width of the base of ocular peduncle; corneal length 0.38–0.44 of ocular peduncle length. Ocular acicles ( Fig. 1A, B) broad; distal margins each with 4–6 spines, separated by approximately 0.50 width of an acicle. Interocular plate ( Fig. 1B) with pair of protrusions.

Antenular peduncles ( Fig. 1A) slender; when fully extended, slightly exceeding length of ocular peduncles; ultimate segments with 2 or 3 long stiff setae on dorsal margin; penultimate segments with tufts of setae on dorsal and ventral margins; basal segment ( Fig. 1C) with single, small ventrodistal spine, ventrally armed with line of 4 or 5 small spines or spinules.

Antennal peduncles ( Fig. 1A, D) long or moderately long, reaching 3/4 of cornea or equal in length to ocular peduncles; fifth segment unarmed; fourth segment with 1 or 2 small spines or spinules on laterodistal margin and tufts of long setae on ventrolateral margin; third segment with ventral margin pronounced, with single, small, ventrosubdistal spine and tufts of long setae; second segment with dorsomesial distal angle bearing sharp spine, dorsolateral distal angle moderately pronounced, ending in bifid spine, lateral margin unarmed; first segment with a moderately strong tipped-spine on ventrolateral subdistal margin. Antennal acicle ( Fig. 1A, B) usually reaching to base of cornea; terminating in bifid spine; mesial margin with 7 or 8 small spines, dorsolateral margin with 1 or 2 small spines distally, ventrolateral margin usually unarmed, occasionally with 1 or 2 small spines.

Maxillule ( Fig. 2A) with proximal endite subrectangular, distal endite subrectangular, enlarged distally; internal lobe with 1 proximal seta and 3 stiff setae or bristles distally. Maxilla ( Fig. 2B) with endopod wide basally, terminating in acute tip, long and distally exceeding scaphognathite. First maxilliped ( Fig. 2C) with endopod reaching approximately 0.80 length of external basal segment. Second maxilliped ( Fig. 2D) without distinguishing characters. Third maxilliped ( Fig. 2E) basis-ischium incompletely fused; coxa usually with 2 small spines; basis with 1 small spine on ventrolateral distal margin; ischium with well developed crista dentata, with 9 or 10 denticles, ventrolateral distal margin with a strong spine; merus with 1 or 2 spines on ventral margin, dorsodistal margin with 1 small spine.

Chelipeds vastly unequal, left larger. Left cheliped ( Figs. 3A, 6A) very stout, 1.50–1.70 times longer than wide. Dactyl ( Fig. 3A, B) terminating in large corneous claw; cutting edge with 5 or 6 large, rounded molar teeth; outer face near to cutting edge with simple or double irregular row of moderately strong, rounded tubercles or scale-like tubercles; upper face with 2 or 3 irregular rows of scale-like tubercles, each scale fringed anteriorly with 1–6 small rounded granules, occasionally terminating in small corneous spine and moderately long plumose setae; inner face ( Fig. 3C) with 3 irregular rows of tufts of long stiff setae, the upper row bearing flattened tubercles armed with 1 or 2 corneous spines. Fixed finger terminating in large corneous claw; cutting edge with 8–11 molar teeth of different size, smaller rounded teeth or granules on subdistal margin of palm. Palm ( Figs. 3A, 6A) with outer face strongly convex, covered with scale-like tubercles of several sizes, largest on distal third and on fixed finger; scales with 1–6 small rounded tubercles or ending in small, corneous spine on distal margin, fringed with moderately long plumose setae, which reach to basis of next scale; upper margin with row of 6 or 7 prominent spines decreasing in size distally; inner face with few flattened tubercles accompanied by tufts of long, stiff setae and scattered, small corneous-tipped spines near lower margin; inner lower margin with row of flattened, triangularly-shaped corneous spines ( Fig. 3C). Carpus ( Fig. 3A) with upper margin bearing row of 4 prominent spines; upper, outer and lower outer faces with numerous tipped-corneous spines and scattered setae; inner face with scattered tufts of long stiff setae or bristles; inner lower angle with 4 rounded spines. Merus ( Fig. 3A) with distal margin of lateral face bearing several corneous-tipped spines, the strongest spine on dorsal face; dorsal face with short transverse subdistal row of small corneous-tipped spines, remainder of dorsal face with tufts of long stiff setae; lateral face with numerous flattened tubercles bearing small corneous spines and tufts of short stiff setae, ventrolateral angle with 1 strong spine; ventromesial margin crested with 6 or 7 teeth or rounded spines, proximal larger. Ischium with ventromesial margin crested with 5 rounded spines and tufts of long setae.

Right cheliped ( Fig. 3D) moderately slender, generally setose. Dactyl terminating in large corneous claw; cutting edge with 6 strong, molar teeth; upper face with 2 or 3 irregular rows of moderately strong, corneous spines accompanied with tufts of long stiff setae; outer face with row of small, corneous spines and tufts of long setae. Fixed finger terminating in large corneous claw; cutting edge with 6 large molar teeth. Palm and fixed finger with outer face bearing numerous flattened tubercles, each bearing 1 or 2 corneous spines and tufts of long, tick setae; distal margin of palm with 3 rounded spines; lower face with double irregular row of flattened tubercles bearing triangularly-shaped, corneous spines ( Fig. 3E); upper margin of palm generally with two rows of 5 prominent corneous-tipped spines; inner face with scattered tufts of long setae, distal margin with 1 or 2 small, corneous-tipped spines. Carpus with 4 prominent, corneous-tipped spines on upper margin; upper face with few moderately strong or strong, corneous-tipped spines; outer and lower outer faces with few flattened tubercles bearing small, corneous spines and tufts of long stiff setae; inner lower face with 2 rounded spines. Merus with distal margin of lateral face bearing several corneous-tipped spines; dorsal face with tufts of long setae; lateral face rugose and with few small spines or spinules and tufts of short setae; ventrolateral angle with large spine; ventromesial margin crested with 6 teeth or rounded spines. Ischium armed with 5 rounded teeth and tufts of long setae on ventromesial margin.

Second ( Fig. 4A, B) and right third ( Fig. 5A, B) pereopods generally similar, but armature of dactyls, propodi and carpi somewhat different between second and right third pairs, second pair slender than right third; of second pair, left slightly shorter than right. Dactyls 1.36–1.44 (second) or 1.50–1.60 (right third) length of propodi, each terminating in strong, corneous claw; dorsal faces with 2 rows of corneous-tipped spines decreasing in size distally accompanied with tufts of long stiff setae; mesial faces ( Figs. 4B, 5B) each with faint longitudinal groove and two longitudinal rows of tufts of stiff setae, one in midline and another dorsally, the latter accompanied by small corneous spines; lateral faces each with faint longitudinal groove and two longitudinal rows of tufts of long stiff setae, one in midline and another dorsally; in the left, second pereopod, dorsal row also bearing small corneous spines; ventral margins each with 2–4 (second) or 2 or 3 (right third) small corneous spines distally and rows of tufts of stiff setae; in the left, second pereopod, ventrolateral row of tufts also bearing small corneous spines on proximal 1/4. Propodi 1.38–1.45 (second, Fig. 4A, B) or 1.40–1.46 (right third, Fig. 5A, B) length of carpi; dorsal faces flattened and very broad (second, Fig. 4C) or comparatively narrower (right third, Fig. 5C), armed with 3 (second) or 2 (right third) irregular rows of flattened tubercles bearing 1 or 2 corneous-tipped spines and tufts of long stiff setae, dorsodistal margins armed with few small corneous spines and setae; lateral faces each with faint longitudinal groove and two rows of long stiff setae, one in midline and another ventral (right third) or both submarginal (second), in the left second pereopod ventral row also bearing small corneous spines, distal margins with 2 or 3 small corneous-tipped spines; mesial faces each with two longitudinal rows of tufts of long, stiff setae, one in midline and another ventrally (right third) or both rows submarginal (second), distal margins with 1 or 2 small corneous-tipped spines; ventral faces each with row of tufts of long stiff setae, in the left second pereopod the tufts are accompanied by small corneous spines. Carpi 0.60–0.70 (second, Fig. 4A) or 0.76–0.86 (right third, Fig. 5A) length of meri; dorsal face of second pereopods with double row of corneous-tipped spines and tufts of thick setae, inner spines larger; dorsal face of right third pereopod with 2 strong corneous-tipped spines distally, remainder of face with flattened spine-like tubercles accompanied with tufts of long stiff setae; dorsodistal angle with 1 spine (second, Fig. 4C) or 2 spines (right third, Fig. 5C); lateral face convex on the median surface, with weak longitudinal faint groove lined by tufts of setae (second and right third), and few short transverse lines of small corneous-tipped spines (second); mesial face flattened, almost naked. Meri with dorsal faces bearing tufts of long setae; ventral faces with double row of small spines (second) and tufts of long setae or only tufts of long setae (right third); second pereopods with 1 corneous-tipped spine at ventrolateral distal angle.

Left third pereopod with dactyl ( Figs. 5D, 13A) 1.50–1.60 length of propodus, terminating in a large corneous claw; mesial face convex ( Fig. 5E), with a weak middle longitudinal groove and two rows of tufts of long, spine-like stiff setae, one in midline and another dorsally, the latter bearing flattened tubercles with 1 or 2 corneous spines; ventromesial margin with dispersed tufts of setae; ventral face with faint groove and 2 corneous spines distally; lateral face ( Figs. 5D, 13A) with scale-like tubercles interrupted by strong, deep, longitudinal groove fainting distally, lined with small tubercles fringed anteriorly with very short setae, below this groove scales forming a longitudinal ridge, each scale with 1–3 small rounded or tipped granules and short plumose setae distally, scales below longitudinal ridge with 1 or 2 small rounded or tipped granules; ventral margin with prominent tipped spines decreasing in size distally and scattered long stiff setae. Scales above groove fringed distally with 1–3 rounded or tipped granules, each scale ending dorsally in strong, corneous-tipped spines partially concealed by tufts of long setae; dorsal face with longitudinal row of flattened tubercles near to dorsomesial margin, each tubercle bearing 1 or 2 corneous spines and tufts of long, spine-like stiff setae. Propodus ( Figs. 5D, 13A) 1.25–1.30 length of carpus, very broad; dorsal face ( Fig. 5F) flattened, with 2 irregular longitudinal rows of flattened tubercles bearing 1 or 2 corneous-tipped spines and tufts of long stiff setae, dorsodistal margin with few small corneous spines and stiff setae; mesial face ( Fig. 5E) flattened, with two longitudinal rows of tufts of short stiff setae, one in midline and another ventrally, distal margin usually with 3 or 4 corneous-tipped spines; lateral face ( Fig. 5D) with a moderately to strongly pronounced, medium longitudinal scaly ridge, both areas upper and lower to ridge weakly concave; scales on longitudinal ridge and lower area fringed distally with 2–6 rounded granules or spines and setae, longer toward ventral edge; scales ending in strong corneous-tipped spines ventrally. Concave area above longitudinal ridge with 2 irregular longitudinal rows of scale-like tubercles fringed distally with 1–4 small rounded granules and short setae; vertical rows of scales on upper area terminating dorsally in tubercles bearing 2 corneous spines partially concealed with tufts of long stiff setae, scales fringed distally with 2–4 rounded or tipped granules and plumose setae, longer toward dorsal edge. Carpus ( Figs. 5D, 13A) 0.90–1.00 length of merus; upper face with row of spines increasing in size distally; external face convex, with faint longitudinal groove flanked ventrally with short transversal row of corneous spines and tufts of long stiff setae, distal margin with several corneous-tipped spines; mesial face flat, smooth, with scattered tufts of stiff setae. Merus similar to that of right third pereopod. Ischium with 1 small rounded spine on ventromesial margin.

Sternite XII (third pereopods) ( Fig. 1E) with anterior lobe bearing elongate projection, with tufts of long setae anteriorly.

Fourth pereopod ( Fig. 1F) subchelate; dactyl with 5 corneous spines on the lateral face ventrally; propodal rasp well developed; carpus with dorsodistal spine.

Fifth pereopod chelate; rasp of dactyl and palm well developed.

Male pleon ( Fig. 4D) with second to fifth left pleopods fringed with long setae, each with well developed exopod and very small endopod.

Uropods ( Fig. 4D) strongly asymmetrical, left larger than right; endopods and exopods with well developed rasps.

Telson ( Fig. 1G) with lateral constrictions, asymetrical; posterior lobes separated by shallow median cleft, left larger than right; terminal margin of left lobule with 3 or 4 strong, corneous spines and stiff setae of various size; terminal margin of right lobule with 4 or 5 strong, corneous spines and stiff setae of various size. Anterior lobe with setae on lateral margins.

Color. In life, unknown. In preserved specimen, shield cream; ocular peduncles faint pink; chelipeds faint purple with orange stains on outer face of carpus, on ventrolateral and lateral subdistal margins of merus; ambulatory legs faint purple.

Distribution. Panama, 7.5 m ( Stimpson, 1859; Ball & Haig, 1974).

Remarks. As noted earlier, Pagurus sinistripes was described by Stimpson (1859: 36) and its short description did not include illustrations of the material he observed. In the short introduction of his 1859 contribution ( Stimpson 1859: 3), he mentioned “The materials used in the preparation of the following paper have been chiefly supplied from the Museum of the Smithsonian Institution,” but there is no way to be sure that the material he used for the description of Pagurus sinistripes came from these collections. A search for Stimpson’s type in the Smithsonian Institution (USNM) collections and inquiries at several museums in the U.S.A. were negative, and by all means it appears that it has been lost. According to Manning (1993), William Stimpson moved to the Chicago Academy of Sciences in 1865 and took with him some 10,000 lots of Crustacea from the Smithsonian, including his type specimens. Unfortunately, the entire collection was lost in the great Chicago fire of 1871 (see Manning 1993: 112). It is, therefore, almost certain that the type of Pagurus sinistripes was destroyed on that occasion. A neotype, collected in Panama, is therefore selected herein to fix the identity of the species (see below).

Considering that the type of Pagurus sinistripes was lost, the question remained of deciding which specimens among the hundreds of specimens reviewed do indeed correspond to Stimpson´s species, i.e., the true “ Dardanus sinistripes ”. According to Stimpson’s statement (1859: 37), Pagurus sinistripes is a large species (...“Length three inches. Length of carapace along median line, one inch; breadth of front, 0.42 inch.”), and in the last line of its description, he indicated that the male on which he based this new species was “Found in Panama by the Rev. J. Rowell”. According to Stimpson´s short description for Pagurus sinistripes , the “acicle of antennae [is] very slender, setose, not spinulose, and shorter than the eyes”. He also described the left cheliped as follows: “hand very thick, surface granulato-squamose, the squamae often spinulose and setose”. Of the left third pereopod Stimpson said: “The last two joints of the left foot of the third pair are flattened, or somewhat excavated on the outer side; this surface is divided along the middle by an obtuse carina, and transversally striated, the striae setose”.

All the specimens available during this study were examined for these characters and one small series of four male specimens collected in Panama closely resembles the description provided by Stimpson for Pagurus sinistripes . Consequently, one of these males was selected as neotype, thus allowing making further progresses in the distinction of the six species of Dardanus occurring along the Pacific coast of America.

Since its description, Dardanus sinistripes has been cited in numerous contributions on decapod crustaceans or hermit crabs of the East Pacific, including catalogues ( Kertstitch 1989; Hickman & Zimmerman, 2000), taxonomic lists ( Rodríguez de la Cruz, 1987; Villalobos-Hiriart et al., 1989; Lemaitre & Álvarez-León 1992; Moran & Dittel 1993; Castro & Vargas 1996; Hendrickx & Harvey 1999; Vargas et al. 1999), and ecology contributions ( Snyder-Conn 1980; Moran 1984). A significant number of specimens used in these studies, however, are not available in curated collections and were probably discarded. It is therefore impossible to confirm the identity of these specimens. Careful revision of material of Dardanus held in the Los Angeles County Museum of Natural History, at the Smithsonian Institution, in the SCRIPPS Invertebtrate Collection in La Jolla, and in the Crustacean Collections of the Instituto de Biología, Mexico D.F., UNAM, the Regional Collection of Invertebrates in Mazatlán, UNAM, the Invertebrates Collection of CICIMAR, La Paz, and the Collection of Crustaceans in the Centro de Ecología de la Costa (CEC), Mexico, failed to uncover additional specimens assignable to D. sinistripes .

The structure of the left third pereopod dactyl and propodus in Dardanus sinistripes , allows separating it from D. stimpsoni , D. janethaigae D. pilosus and D. magdalenensis . In D. sinistripes , on the lateral face of the left third pereopod dactyl, there generally is a scaly, rounded longitudinal ridge which is formed by the rising of scales below the median longitudinal groove, and there also is a weak concavity proximally between this ridge and the ventrolateral margin. These ridge and concavity are not present in the other species ( Fig. 36D, Table 1). Armature on lateral face of the left third pereopod propodus is also different. The median concave area is broader and bears 2 irregular longitudinal rows of scale-like tubercles fringed distally with 1–4 rounded granules, instead of bearing one longitudinal row of small tubercles. The area below the median longitudinal ridge is weakly concave, and this concavity is not present in the other five species. Left cheliped in D. sinistripes ( Fig. 36A, Table 1) is slender, as in D. magdalenensis , but proportionally longer compared to the latter. In the other four species, the left cheliped is shorter and broader than in D. sinistripes . Furthermore, the armature on the outer face of palm in D. sinistripes is different, scales are smaller and numerous, and spines on upper margin are smaller compared to D. stimpsoni , D. janethaigae D. pilosus and D. magdalenensis . There are one or two irregular rows of small rounded teeth or granules on subdistal margin of palm ( Fig. 36C), which are never seen in D. stimpsoni , D. janethaigae , D. pilosus and D. magdalenensis . Cutting edge of fixed finger ( Fig. 36A) in D. sinistripes bears 8–11 teeth, whilst in the other species it is armed with only 5 or 6 teeth. The scale-like tubercles on the upper face of dactyl are smaller than in the other four species, and the armature on the upper face of carpus differs slightly from these four species. There are usually three longitudinal rows of moderately strong spines of same size on the upper face of carpus in D. sinistripes , in lieu of two longitudinal rows of small or moderately small and one row of strong or moderately strong spines between these two; besides, the outer distal margin bears small spines, while spines are subdistal in the other species. Dardanus sinistripes also features ocular peduncles proportionally longer in relationship to the shield length (ca 2/3 vs. 1/3–3/5) ( Table 1). The merus of the third maxilliped is armed with 1 or 2 small spines instead of 3–5 as in the other four species. The spines on distal margin of telson are smaller than in D. stimpsoni , D. janethaigae , D. pilosus , and D. magdalenensis .