Dardanus pilosus, Parente & Hendrickx, 2009

Parente, Manuel Ayón & Hendrickx, Michel E., 2009, 2323, Zootaxa 2323, pp. 1-71 : 53-60

Dardanus pilosus n. sp.

( Figs. 6E, 27–30, 35A, 37 F-J)

Material examined. Type material. Holotype male (SL 7.48 mm), Clarion Island , Mexico, 24 Mar 1938, coll. S. A. Glassell, 73–110 m ( USNM acc. No. 207834) . Paratype, 1 ovigerous female (SL 9.20 mm), Sulphur Bay , Clarion Island, Revillagigedo Islands, Mexico, stn. 917-39, 16 Mar 1939, 51– 82 m ( LACM CR 1939 - 015.1 ) .

Diagnosis. Merus of third maxilliped with at least 2 spines on ventral margin. Left cheliped short and broad. Setae on outer face of palm of left cheliped long, plumose, usually reaching subdistal margin of the next scale. Scales on the palm of left cheliped small and subrectangular concealed with long plumose setae. Outer lower angle of carpus of left cheliped bearing a small spine. Upper face of dactyl of left cheliped with 2 rows of scale-like tubercles, terminating in rounded granules or tipped spines. Outer face of palm of the left cheliped and the lateral face of the left third pereopod dactyl and propodus concealed with long plumose setae. Lateral face of dactyl of left third pereopod with scales on both sides of longitudinal groove, which are fringed with small corneous-tipped spines and long plumose setae. Corneous-tipped spines along entire ventrolateral margin of the left third pereopod dactyl.

Description. Shield ( Figs. 27A, 35A) as long as broad; anterior margin between rostrum and lateral projections shallowly concave; lateral margins convex, somewhat irregular, with row of small spines on anterior 1/3 and tufts of long setae. Dorsal face with scarce stuffs of setae; weakly calcified Y-shaped linea present posteriorly. Rostral lobe indistinct. Lateral projections produced, obtusely triangular, bearing 1 small marginal spine. Posterior carapace lateral elements well calcified, unarmed. Branchiostegites unarmed.

Ocular peduncles ( Figs. 27A, 35A) 0.60 length of shield, stout, usually with 12 bristles on the superior notch; corneas dilated, 1.40–1.45 the width of the base of ocular peduncle; corneal length 0.40 of ocular peduncle length. Ocular acicles ( Fig. 27A, B) broad; distal margins each with 6–8 spines, inner margins with 1 spine, tips corneous; separated by approximately 0.40 width of an acicle. Interocular plate ( Fig. 27B) transversally subrectangular, with pair of protrusions.

Antenular peduncles ( Fig. 27A) slender, when fully extended, exceeding by 1.33 length of ocular peduncles; ultimate segment with 4 long stiff setae dorsally; penultimate segment with 2 long, stiff, distal setae in dorsal margin and tufts of long setae proximally; basal segment ( Fig. 27C) with ventromesial distal angle bearing 1 small spine, ventral margin bearing usually 4 small spines.

Antennal peduncles ( Fig. 27A, D) as long as ocular peduncles; fifth segment unarmed; fourth segment with 1 or 2 small spines or spinules on dorsodistal margin; third segment produced ventrodistally, with 1 spine at ventrosubdistal margin; second segment with dorsomesial distal angle bearing one spine and one smaller subdistal spine, dorsolateral distal angle produced, terminating in bifid corneous-tipped spine; first segment with ventrolateral distal margin bearing 1 or 2 small spines. Antennal acicle ( Fig. 27A, B, D) terminating in strong, single, corneous-tipped spine, exceeding slightly basis of cornea; dorsomesial margin with 5 small spines, dorsolateral margin with 1 or 2 small spines, ventrolateral margin bearing 1 or 2 small spines. Antennal flagellum very long, each segment with very short setae.

Third maxilliped ( Fig. 27E) with basis-ischium incompletely fused; coxa with 2 moderately strong spines on ventrodistal margin; basis unarmed; ischium with well developed crista dentata, with 11 or 12 denticles; ventrolateral distal margin with 1 strong spine. Merus with 2 or 3 spines on ventral margin, dorsodistal margin with 1 strong spine.

Chelipeds vastly unequal, left larger. Left cheliped very stout, 1.40 times as long as wide, proportion similar in male and female, but not similar in armature. Cheliped in female ( Figs. 6E, 28A): dactyl terminating in large corneous claw; cutting edge with 5 strong, calcareous molar teeth; outer face with row of strong, rounded, spine-like tubercles; upper face with 2 rows of scale-like tubercles, scales on inner row are margined anteriorly with 1 or 2 strong, corneous-tipped spines and small granules, median row with scales fringed anteriorly with 1–5 small granules and tufts of long plumose setae; inner face with longitudinal row of simple or bifid, corneous spine-like tubercles near upper margin. Fixed finger terminating in large corneous claw; cutting edge with 6 strong, calcareous molar teeth. Palm with 2 irregular rows of strong to prominent corneous-tipped spines on upper face; upper outer face with 5 irregular longitudinal rows of scale-like tubercles, each scale bearing 1 strong rounded spine and 1–3 small granules; outer face strongly convex, bearing irregular numerous transversal rows of scale-like tubercles; scales larger on distal 1/3 and fixed finger, each scale fringed distally with 1–8 rounded granules and long plumose setae, setae reaching to half of contiguous scale; lower margin and lower portion of inner face ( Fig. 28B) with several flattened, triangleshaped, spine-like tubercles. Carpus with upper margin bearing 1 row of prominent, corneous-tipped conical spines; outer face with several prominent corneous-tipped spines, lower outer face with several strong corneous-tipped conical spines on distal and proximal margins; ventromesial distal margin usually with 4 moderately strong rounded spines. Merus with distal margin of lateral face bearing several corneous-tipped spines; dorsal face with short, transverse subdistal row of small, corneous-tipped spines, rest of margin with tufts of long stiff setae; ventromesial margin crested with 7 strong rounded spines or teeth; lateral faces with several flattened tubercles bearing small corneous spines, ventrolateral distal angle with 1 strong, corneoustipped spine. Ischium with 5 strong rounded spines on ventromesial margin.

Left cheliped of holotype male ( Figs. 35A) very stout. Dactyl terminating in large corneous claw; upper face with 2 longitudinal rows of strong, corneous-tipped conical spines, spines on inner row generally terminating in bifid spine; outer face with one row of strong, corneous-tipped spines, all spines fringed anteriorly with tufts of long plumose setae; inner face with 2 rows of tufts of long stiff setae, upper row accompanied with corneous-tipped spines; cutting edge with row of 5 large, calcareous molar teeth. Fixed finger terminating in large corneous claw; cutting edge with row of 6 large, calcareous molar teeth. Palm with outer face strongly convex; outer faces of palm and fixed finger covered with numerous corneous-tipped conical spines and scale-like tubercles, the latter mostly on fixed finger, each scale fringed distally with 1–3 small corneous spines; spines and scales fringed anteriorly with tufts of long plumose setae; upper face of palm with 2 rows of prominent corneous-tipped spines; inferior margin and lower portion of inner face ( Fig. 28C) with several flattened, triangle-shaped, spine-like tubercles. Armament and setation of carpus and merus similar to those of female.

Right cheliped ( Fig. 28D, E) in males and females moderately slender, generally setose. Dactyl terminating in large corneous claw; cutting edge with row of 5 molar teeth; upper face with 3 irregular longitudinal rows of corneous-tipped spines; outer face with 4 small corneous-tipped spines accompanied by tufts of long, stiff setae. Fixed finger terminating in large corneous claw; cutting edge with 6 molar teeth. Palm and fixed finger with outer face bearing numerous flattened triangle-shaped, spine-like tubercles; lower face with row of flattened triangle-shaped, spines-like tubercles ( Fig. 28E); upper margin of palm with 2 rows of prominent corneous-tipped conical spines. Carpus with 10 peripheral, strong corneous-tipped spines on upper face; outer and lower outer faces with flattened tubercles bearing moderately strong, corneous-tipped spines; ventromesial distal margin usually with 3 rounded spines. Merus with distal margin of lateral face bearing several corneous-tipped spines; dorsal face with short transverse subdistal row of small, corneoustipped spines; ventromesial margin crested with 7 rounded spines or teeth, 3 proximal larger; lateral faces with several flattened tubercles bearing small corneous spines, ventrolateral distal angle with 1 strong, corneoustipped spine. Ischium with 5 strong rounded spines on ventromesial margin.

Second ( Fig. 29A–D) and right third ( Fig. 35A) pereopods generally similar; of second pair, left slightly shorter than right. Dactyls 1.30–1.40 (second) or 1.60 (right third) length of propodi, each terminating in large corneous claw; dorsal surfaces ( Fig. 29C) each with 1 or 2 rows of corneous spines and tufts of stiff setae, setae denser distally; lateral and mesial faces ( Figs. 29A, B, 30H) each with two longitudinal row of tufts of long stiff setae, one in midline and another dorsally, the latter bearing small corneous spines; ventral margins each with 3–6 (second) or 3 (third) corneous spines distally and rows of tufts of stiff setae. In the paratype female, lateral face ( Fig. 30E) of right third pereopod dactyl with weak longitudinal furrow, lined in midline with tufts of long stiff setae, dorsal and ventral margins with short, transverse rows of small corneous spines accompanied with short plumose setae and scarce long stiff setae. Propodi 1.40 length of carpi; dorsal faces flattened and very broad (second, Fig. 29D) or comparatively narrower (right third, Fig. 30G), each armed with 3 irregular longitudinal rows of flattened tubercles bearing 1–3 corneous spines and tufts of stiff setae, dorsodistal margins with several small corneous spines and stiff setae; lateral faces each with two rows of tufts of long stiff setae, one in midline and another ventrally, in the left second ( Fig. 29A) both rows of tufts also bearing small corneous spines, laterodistal margins with 1–3 small corneous-tipped spines; mesial faces ( Figs. 29B, 30I) each with 2 longitudinal rows of tufts of long stiff setae, one in midline and another ventrally (right third) or one sub-medium and another ventrally (second), in the second pair upper row generally bearing small corneous spines; ventral margins with rows of tufts of long stiff setae, in the left second also bearing small corneous spines. Lateral face of right third pereopod propodus of paratype female ( Fig. 30F) bearing one weak longitudinal furrow lined with tufts of long stiff setae, both sides of furrow with transverse rows of 1–3 small corneous spine and very short, fine setae. Carpi 0.70 (second) or 0.90 (right third) length of meri; dorsal margins each with several corneous-tipped conical spines, distal larger; one row of small corneous spines running near dorsal spines; dorsolateral distal angles each usually bearing 1 moderately strong, corneoustipped spine; lateral faces convex, with weak longitudinal furrow flanked ventrally by flattened tubercles bearing tufts of stiff setae and few small corneous spines distally (right third, Fig. 30F) or with short vertical rows of small corneous spines and tufts of stiff setae (second, Fig. 29A). Meri laterally compressed, each with tufts of long stiff setae on dorsal face; ventrolateral margins usually with 1 distal, moderately strong corneoustipped spine; ventral faces with double irregular row of small spines or granules (second) or scarce small spines or granules distally (third) and tufts of long stiff setae.

Left third pereopod ( Figs. 30A–D, 35A) stout. Dactyl 1.40 length of propodus, terminating in large corneous claw; dorsal face ( Fig. 30D) with row of flattened tubercles bearing 1 corneous spine and tufts of stiff setae, setae denser distally; mesial face ( Fig. 30C) convex, with two longitudinal rows of tufts of long stiff setae, one in middle line and another dorsally, the latter generally bearing small corneous spines; lateral face ( Figs. 30A, 35A) flattened, with deep longitudinal groove vanishing distally, lined with small flattened tubercles fringed anteriorly with long plumose setae; either sides of longitudinal groove are transverse rows of scales; scales are fringed distally with small corneous-tipped spines and long plumose setae, setae reaching distal margin of contiguous scale and longer near edges of dactyl; scales terminating in strong corneous-tipped spines on ventral and dorsal margins, decreasing in size distally, concealed by tufts of long plumose setae; ventral margin with 3 strong corneous spines distally and rows of tufts of long setae. Propodus 1.30 length of carpus; lateral face ( Figs. 30A, 35A) strongly convex with two rows of scales on both sides of a bare median area, lower area narrower than upper area. Scales fringed distally by small corneous-tipped spines and plumose setae, setae longer toward edges of propodus; scales terminating in strong, corneous-tipped spines on ventrolateral margin, and large tubercles armed with 2 strong corneous-spines on dorsolateral margin, partly concealed by tufts of long plumose setae and scarce long stiff setae; mesial face ( Fig. 30C) with two longitudinal rows of stiff setae, distomesial margin with 3 or 4 corneous-tipped spines; dorsal face ( Fig. 30D) with 2 irregular longitudinal rows of flattened tubercles bearing 1 or 2 moderately strong corneous spines and tufts of stiff setae, dorsodistal margin with few small corneous spines and stiff setae. Carpus ( Fig. 30B) 0.90 length of merus; dorsal margin with row of corneous-tipped spines increasing in size distally; dorsodistal angle bearing 1 moderately strong corneous-tipped spine; lateral face convex, with longitudinal weak groove flanked ventrally by flattened tubercles bearing small corneous spines and tufts of stiff setae, laterodistal margin spiny. Merus laterally compressed, with tufts of long stiff setae on dorsal face; ventrolateral distal margins usually with 1 moderately strong corneous-tipped spine; ventral face with scarce small spines or granules distally and tufts of long stiff setae.

Sternite XII (third pereopods) ( Fig. 27F) with anterior lobe subrectangular, bearing an elongate protuberance with tuft of long setae anteriorly.

Fourth pereopod ( Fig. 27G) subchelate; dactyl with 6 or 7 corneous spines on lateral face ventrally; propodal rasp well developed; carpus with sharp dorsodistal spine.

Fifth pereopod chelate; rasps of dactyl and propodus well developed.

Male pleon ( Fig. 29E) with second to fifth left pleopods fringed with long setae, each with well developed exopod. Female pleon with second to fifth left pleopods fringed with long setae; second to fourth triramous; fifth biramous, endopod very small; single, slightly curved, elongate fleshy membranous ( Fig. 29F) fringed with long setae present between fourth and fifth pleopods.

Uropods ( Figs. 29E, 35A) strongly asymmetrical, left larger than right; endopods and exopods with well developed rasps.

Telson ( Fig. 27H) with lateral constrictions; marginal area partially calcified; posterior lobes separated by median cleft, left larger than right; terminal margin with 4 (left) or 4 or 5 (right) corneous spines and setae of different sizes; anterior lobes with long setae on lateral margins.

Color. In life, unknown. In fixed specimen the shield is cream with light orange spots anteriorly. Ocular peduncles rosaceous; cornea dark brown or black. Ocular acicles, antennal segments 1–4, and antennal acicles cream; ultimate antennal segment, antennal flagella and antenular peduncles straw yellow or pale. Chelipeds with outer and inner faces of palm light orange over ground cream; dactyl and fixed finger orange over ground cream; scales on fixed finger with proximal half orange and cream distally. Carpus cream and orange spotted on inner lower face and outer lower face. Merus cream with subdistal orange band. Ambulatory legs with dactyls and propodi light orange over ground cream; carpi with ventral face orange over ground cream, rest of surface cream with orange thin band on distal third. Meri cream with orange spots on distal margin and light, subdistal orange band.

Etymology. The specific name is derived from pilosus (hairy, covered with hair), in reference to the long setae on the lateral face of the left third pereopod dactyl and propodus and on the palm outer face of the left cheliped.

Distribution. Know only from Clarion Island, Revillagigedo Archipielago, Mexico; 51– 110 m.