Dardanus nudus, Parente & Hendrickx, 2009

Parente, Manuel Ayón & Hendrickx, Michel E., 2009, 2323, Zootaxa 2323, pp. 1-71 : 14-27

Dardanus nudus n. sp.

( Figs. 6B, 7–12, 13B, 36F–J)

Dardanus sinistripes . — Hendrickx, 1994: 27–31 (in part, see material examined and additional material).— Hendrickx et al., 1997a: 9 (in part, see material examined and additional material).— Hendrickx et al., 1997b: 70–72 (in part, see additional material).

Material examined. Type material. Holotype male (SL 16.00 mm), off Santa Cruz Bay , Oaxaca, 15º7.9’N, 92º58.8’W, Mexico, CEEMEX P7 R / V “El Puma”, 11 May 1992, 28 m, trawl, EMU-8463 . Paratypes: 1 male (SL 12.00 mm), off Puerto Madero , Chiapas, Mexico, 14º42’N, 92º32’W, CEEMEX P7 R / V “El Puma”, 13 May 1992, 25 m, trawl, EMU-4809 ; 3 males (SL 5.38–6.00 mm), off Santa Cruz Bay , Oaxaca, 15º7’N, 95º58’W, Mexico, CEEMEX P7 R / V “El Puma”, 11 May 1992, 28 m, trawl, USNM-1123702 ; 5 males (SL 6.70-12.00 mm), 1 female (SL 11.50 mm), ATLAS II, stn. 5B-08, 16º38’00–18”N, 99º40’24”–99º41’48’W, 17 Apr 1982, 54 m, trawl, EM-3275 ; 3 males (SL 2.40–5.40 mm), 6 females (SL 3.10–3.90 mm), 4 juvs., off San Jose Light , Guatemala, stn. 930-39, 23 Mar 1939, 22 m, LACM-CR 1939 - 033.2 ; 1 male (SL 5.3 mm), 2 NS, TEPE 78-9 Golfo de Fonseca , 13º01.1’N, 88º01.7’W, El Salvador, R / V A. Helix, 04 Apr 1978, trawl, 42 m, SIO-C4085 .

Additional material. 1 male (SL 14.10 mm), off Boca de San Francisco , Oaxaca, 16º9’N, 94º57’W, Mexico, CEEMEX P7 R / V “El Puma”, 9 May 1992, 26 m, trawl, EMU-4798 ; 2 males (SL 4.40–5.09 mm), 7 NS, off Barra Tonala, Chiapas, Mexico, 15º53’N, 93º53’W, CEEMEX P7 R / V “El Puma”, 10 May 1992, 34 m, trawl, EMU-4815 ; 6 males (SL 3.27–9.33 mm), 3 females (SL 2.93–4.67 mm), off Santa Cruz Bay , Oaxaca, 15º7’N, 95º58’W, Mexico, CEEMEX P7 R / V “El Puma”, 11 May 1992, 28 m, trawl, EMU-4816 ; 1 male (SL 7.40 mm), off San Lorenzo River , Sinaloa, Mexico, 24.13ºN, 107.48º W, CEEMEX P8 R / V “El Puma”, 25 May 1992, trawl, 16 m, EMU-4830A ; 1 ovigerous female (SL 4.60 mm), ATLAS II, stn. 1B-01, 16º22’30”– 16º21’48”N, 98º39’30”– 98º28’42”W, 15 Apr 1982, 20 m, EM-3242 ; 1 male (SL 7.70 mm), 10 miles SW of Secas Islands , Panama, stn. 944-39, 23 Mar 1939, 55 m, LACM CR 1939 - 047.2 ; 9 males (SL 6.90–15.00 mm), 2 females (SL 6.10–9.00 mm), 1 ovigerous female (SL 8.90 mm), Gulf of Panama, Sep 1958, trawl, 27 m, LACM CR 1958 - 003.1 .

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 very short, simple. Scales on the palm of left cheliped small and subrectangular. Outer lower angle of carpus of left cheliped bearing a small spine. Upper face of dactyl of left cheliped with 3 to 4 irregular rows of large rounded, spine-like tubercles. Outer face of palm of the left cheliped and the lateral face of the left third pereopod dactyl and propodus with very short, simple setae, giving a bare appearance. Lateral face of dactyl of left third pereopod with spine-like tubercles accompanied with very short simple setae on proximal half of the lower and upper areas to longitudinal groove. Corneoustipped spines on proximal half of ventrolateral margin of the left third pereopod dactyl.

Description. Shield ( Fig. 7A, B) 0.92–1.03 times longer than broad; anterior margin between rostrum and lateral projections shallowly concave; lateral margins slightly convex, somewhat irregular, with small spines or tubercles on anterior 0.33 and tufts of long setae. Anterolateral margins usually with few small spines or granules. Dorsal surface of shield flat, with few tufts of short setae; weakly calcified Y-shaped line present posteriorly. Rostral tooth broadly blunt, 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. 7A) 0.33–0.45 length of shield, thick, weakly compressed at the middle, usually with 7 bristles on the superior notch. Cornea weakly dilated, 1.10 the width of the base of ocular peduncle; corneal length 0.36–0.44 of ocular peduncle length. Ocular acicles ( Fig. 7B) broad; distal margins each with 4–7 spines, separated by approximately 0.33 width of an acicle. Interocular plate ( Fig. 7B) transversally subrectangular, anterior margin biconvex.

Antenular peduncles ( Fig. 7A) slender; when fully extended exceeding by 0.25 length of ocular peduncles; ultimate segment with 3 tufts of long stiff setae on dorsal margin; penultimate segments with tufts of setae on dorsal and ventral margins; basal segment ( Fig. 7D) with single small ventrodistal spine and armed ventrally with line of 3 small spines or spinules.

Antennal peduncles ( Fig. 7A, C) long or moderately long, 1.50 length of 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 produced, 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 small spine on ventrolaterodistal margin. Antennal acicle ( Fig. 7A, B, C) usually reaching to base of cornea; terminating in bifid/or trifid spine; mesial margin with 5–9 spines, dorsolateral margin with 1 or 2 small spines at distal third, ventrolateral margin usually unarmed, occasionally with 1 or 2 small spines.

Maxillule ( Fig. 8A) with proximal endite subrectangular, distal endite subrectangular, enlarged distally; internal lobe with 1 proximal seta and 4 stiff setae or bristles distally. Maxilla ( Fig. 8B) with endopod 1.30 length of distal ending of scaphognathite, wide basally and terminating in acute tip with a subdistal setae. First maxilliped ( Fig. 8C) with endopod reaching approximately 0.80 length of external basal segment; epipodite usually with a distal bristle. Second maxilliped ( Fig. 8D) without distinguishing characters. Third maxilliped ( Fig. 8E) with incompletely fused basis-ischium; coxa and base each usually with 1 strong spine on ventrolaterodistal margin; ischium with well developed crista dentata, with 10 or 11 denticles; ventrolaterodistal margin with a strong spine, occasionally with 1 or 2 small, subdistal spines; merus with 3–5 spines on ventral margin, dorsodistal margin with 1 strong spine, occasionally with 1 or 2 small subdistal spines.

Chelipeds vastly unequal, left larger. Left cheliped ( Figs. 6B, 9A) very stout, 1.50 times longer than wide, proportion and armature generally similar in males and females. Dactyl ( Fig. 9A, C) terminating in large corneous claw; cutting edge with 5 or 6 large, rounded molar teeth; outer face with 4–6 irregular longitudinal rows of rounded, spine-like tubercles, outer margin near to cutting edge with row of large rounded, spine-like tubercles; upper face with 3 or 4 irregular rows of large rounded, spine-like tubercles; upper inner face with 2 irregular rows of spine-like tubercles. Fixed finger terminating in large corneous claw; cutting edge with 5 or 6 large, rounded molar teeth, followed by 3 or 4 much smaller proximal teeth, 1 or 2 irregular rows of small rounded, submarginal granules near distal margin of palm. Palm ( Figs. 6B, 9A, B) with outer face strongly convex, covered with spine-like tubercles on the proximal 2/3, distal 1/3 and fixed finger covered with scales of different size, scales with 1–5 small rounded tubercles or ending in small, corneous spine on distal margin, scales fringed with fine, short bristles-like setae, giving a nude appearance; upper outer face with 6 or 7 irregular longitudinal rows of spine-like tubercles; upper margin with row of 7–9 prominent spines; lower margin and lower portion of inner face with numerous rounded spine-like tubercles and scattered tufts of long stiff setae or bristles ( Fig. 9D). Carpus ( Fig. 9A, E) with upper margin bearing row of 4 prominent spines; upper face nearly flattened, nude, spiny; outer face convex, with few small corneous spines, distal margin with small corneous spines; lower outer face with spine-like tubercles on distal and proximal margins; inner face with scattered tufts of long, stiff setae or bristles; ventromesial angle with 4 corneous spines. Merus ( Fig. 9E) with lateral distal face bearing few corneous spines, the strongest spine on dorsal face; ventrolateral angle with 1 strong spine; ventromesial margin crested with 6–8 teeth or rounded spines, proximal larger. Ischium with ventromesial margin crested with 5 rounded spines, increasing in size distally.

Right cheliped ( Fig. 9F) moderately slender, generally setose. Dactyl of right cheliped 1.50 length of palm, terminating in large corneous claw; cutting edge with 5 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 5 large molar teeth. Palm and fixed finger with outer face bearing numerous flatted tubercles, bearing 1 or 2 corneous spines and tufts of long, stick setae; lower face with row of flattened tubercles bearing triangularly-shaped corneous spines ( Fig. 9G); upper margin of palm generally with 2 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; upper distal and outer edges spiny; outer and lower faces with few spine-like tubercles; inner face with scarce tufts of long stiff setae or bristles; inner lower face with 3 strong rounded spines. Merus with few spines on outer distal face, larger spines on dorsal face; dorsal face with tufts of long setae; ventrolateral angle with large spine; ventromesial margin crested, divided into two areas by a fissure, proximal area with 3 teeth or rounded spines, distal area with 5 teeth or rounded spines smaller than proximal. Ischium armed with 5 strong teeth on mesial margin.

Second ( Fig. 10A–E) and right third ( Fig. 11A–F) pereopods generally similar, but armament of propodi and carpi somewhat different between second pair and right third, second pair slender than right third; of second pair, left slightly shorter than right. Dactyls 1.30–1.50 (second) or 1.20–1.50 (right third) length of propodi, each terminating in strong corneous claw; dorsal surfaces ( Fig. 10B) with 1 row of corneous-tipped spines decreasing in size distally, accompanied with tufts of long stiff setae denser on distal third; lateral and mesial faces ( Figs. 10A, C, 11 A, C) each with a 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; ventral margins each with 1 or 2 small corneous spines and rows of tufts of stiff setae. Propodi 1.20–1.50 (second, Fig. 10A, D, E) or 1.30–1.50 (right third, Fig. 11B, D, E) length of carpi; dorsal faces flattened and very broad (second, Fig. 10D) or comparatively narrower (right third, Fig. 11E), 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; lateral faces each with two rows of stiff setae one in midline and another ventral, distal margins with 3 or 4 small corneous-tipped spines; mesial faces of second pereopods each with 2 longitudinal rows of tufts of stiff setae, one ventrally and another near midline, in the left pereopod ventral row bearing small corneous spines, right third with two longitudinal rows of tufts of stiff setae, one ventrally and another in midline, distal margins with 1–3 small corneous-tipped spines; ventral faces with row of tufts of long stiff setae, in the left second pereopod the tufts are accompanied by small corneous spines. Carpi 0.70–0.80 (second, Fig. 10A, D) or 0.80–0.90 (right third, Fig. 11F) length of meri; dorsal face with row of strong, corneous-tipped spines and tufts of very thick setae each; dorsodistal angle with 1 spine (right second and third, Fig. 11F) or 2 spines (left second, Fig. 10D); lateral face convex on the median surface, with weak longitudinal groove lined by tufts of setae (right third) or also bearing few short transverse lines of small corneous-tipped spines; mesial face flattened, almost naked. Meri with dorsal faces bearing tufts of long setae; mesial and lateral faces with scattered tufts of short 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. 12A, 13B) 1.50–1.60 length of propodus, terminating in a large corneous claw; mesial face convex ( Fig. 12D), with a weak middle longitudinal groove and two rows of tufts of long stiff setae, one in midline and anotherand another dorsally, the latter bearing flattened tubercles with simple or bifid corneous spines; ventromesial margin with dispersed tufts of setae; ventral face with groove on proximal 2/3, distally with 1 or 2 corneous spines; lateral face flattened ( Figs. 12A, B, 13B), with a proximally deep longitudinal grove, fainting distally, irregular transversal rows of flattened, corneous spine-like tubercles on both sides of groove, tubercles accompanied with very short, simple, fine setae on proximal 2/3, distal third with tufts of very short, simple, fine setae; dorsal face with longitudinal row of flattened tubercles accompanied with tufts of long stiff setae, which are denser distally, proximal tubercles occasionally bearing small corneous spines; dorsolateral margin ( Fig. 12B, C) with strong, black-tipped spines, decreasing in size distally to small corneous spines; ventrolateral margin with rounded spine-like tubercles on the proximal 1/2 or 2/3, unarmed distally. Propodus ( Figs. 12A, E, F, 13B) 1.20–1.40 length of carpus, very broad; dorsal face ( Fig. 12E) flat, with 2 or 3 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 short stiff setae; dorsolateral margin with strong flattened tubercles terminating in simple or bifid corneous-tipped spine accompanied by 1 or 2 long stiff setae; mesial face ( Fig. 12F) flattened, with two longitudinal rows of tufts of stiff setae, one in midline and another ventrally, distal margin usually with 6 strong, corneous-tipped spines; lateral face ( Figs. 12A, 13B) with uniform middle convex area, with transversal scales on lower area, which are fringed distally with small rounded granules or corneous-tipped spines and short fine setae, and irregular transversal rows of spine-like tubercles on upper area, accompanied with short faint setae, giving a naked appearance to propodus; ventrolateral margin with strong, rounded spine-like tubercles. Carpus ( Fig. 12A) 0.90–1.00 length of merus; upper face spiny, larger spines distally; external face convex, with faint longitudinal groove flanked ventrally with flattened tubercles bearing small corneous-tipped spines and tufts of long stiff setae, subdistal margin with numerous small, corneous-tipped spines; mesial face flattened, smooth, with scattered tufts of stiff setae; ventral face unarmed, with two tufts of long stiff setae. Merus similar to that of right third pereopod. Ischium with 1 moderately strong spine on ventromesial margin.

Sternite XII (third pereopods) ( Fig. 7E) with anterior lobe rectangular bearing a median subcircular lobule with long setae.

Fourth pereopod ( Fig. 7F) subchelate; dactyl with 3–6 ventrolateral corneous spines; propodal rasp well developed; carpus with small dorsodistal spine, occasionally unarmed.

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

Male pleon ( Fig. 10F) with second to fifth left pleopods fringed with long setae, each with well developed exopod and very small endopod; single, short, subcircular, fleshy membranous protuberance fringed distally with long setae present between fourth and fifth pleopods. Female pleon ( Fig. 10G) with second to fifth left pleopods fringed with long setae; second to fourth large, triramous; fifth small, biramous, endopod very small; single, elongate, fleshy membranous protuberance ( Fig. 10G, H) fringed with long setae present between fourth and fifth pleopods.

Uropods ( Fig. 10F, G) strongly asymmetrical, left larger than right; endopods and exopods with well developed rasp.

Telson ( Fig. 7G) with lateral constrictions, asymetrical; posterior lobes separated by shallow median cleft, left larger than right; terminal margin of left lobule with 2–4 strong, corneous spines and stiff setae of various size; right terminal margin with 3 or 4 strong, corneous spines and stiff setae of various size. Anterior lobe with setae on lateral margins.

Color. In life unknown. In long time fixed specimens, the abdomen and carapace are cream colored. Ocular peduncles rosaceous, cornea black. Ambulatory legs with faint orange spots on a cream background. Merus and carpus of left cheliped with orange spots on a cream background, orange stronger on distal outer surface; outer surface of the palm, fixed finger, and upper surface of dactyl orange; upper surface of palm faint orange on a cream background; surface near cutting edges of dactyl and fixed finger and their distal faces cream to white. Right cheliped with faint orange spots on a cream background, orange spots stronger on distal outer surface of merus.

Etymology. The specific name is derived from nudus (nude) to indicate the nude appearance of the palm outer face of the left cheliped, and of the lateral face of the left third pereopod dactyl and propodus.

Distribution. From off San Lorenzo River, Sinaloa, Gulf of California, off Michoacan, and in the Gulf of Tehuantepec, Mexico, to Gulf of Panama; 16 to 55 m.

Remarks. Dardanus nudus n. sp. is easily distinguished from the other five species. The outer face of the palm of the left cheliped and the lateral face of the left third pereopod dactyl and propodus bear very short, simple setae ( Fig. 36F, I, Table 1), giving a bare appearance, in comparison to long to moderately long plumose setae as observed in the other species. The outer lower median distal third of palm and fixed finger bear scale-like tubercles, and the rest of the outer face of palm is covered with small to moderately strong spine-like tubercles. Such armature is not found in the other species. The lower margin of the left cheliped also bears rounded granules, instead of strong to moderately strong, flattened triangularly-shaped corneous spines ( Fig. 36G). The armature on the ventrolateral margin of the left third pereopod dactyl also separates D. nudus from the other five species. Row of strong to moderately strong corneous-tipped spines is observed along this margin in D. sinistripes , D. stimpsoni , D. janethaigae , D. pilosus and D. magdalenensis , while these spines occur only on proximal half in D. nudus ( Fig. 36I). The sculpture of the lateral ace of the left cheliped, and of the lateral face of the left third pereopod dactyl and propodus in D. nudus is also different, bearing small rounded spine-like tubercles accompanied with very short setae, in lieu of transverse rows of scales fringed distally with long to moderately long plumose setae as in the other five species. Other differences with respect to the rest of the species are: the antennal acicles bear small spines on mesial margin in D. nudus , instead of dorsomesial small spines; the anterior lobe of sternite of third pereopods in D. nudus bears a median subcircular lobule with tuft of long setae, vs. elongate projection with tufts of long setae anteriorly; the distal margin of telson ( Fig. 36J, Table 1) is armed with 2 or 3 (left) and 3 or 4 (right) corneoustipped spines, whilst the other species have 4 or 5 (left) and 4–7 (right) spines.