Dardanus magdalenensis, Parente & Hendrickx, 2009

Parente, Manuel Ayón & Hendrickx, Michel E., 2009, 2323, Zootaxa 2323, pp. 1-71 : 60-68

Dardanus magdalenensis n. sp.

( Figs. 31–34, 35B,C, 37K–N)

Dardanus sinistripes .— Haig et al., 1970: 16 (in part, see material examined). Ball & Haig, 1974: 97 (in part, see additional material).

Material examined. Type material. Holotype male (SL 7.50 mm), Magdalena Bay , Baja California, Mexico, 24º37’59”N, 112º05’30”W, 09 Apr 1889, R / V "Albatross", beamtrawl, 31 m, USNM-1123701 . Paratypes, 1 ovigerous female (SL 19.00 mm), Cedros Island , Baja California, Mexico, USNM-39125 ; 1 female (SL 9.00 mm), Magdalena Bay , Baja California, Mexico, 24º37’59’N, 112º05’30”W, 09 Apr 1889, R / V "Albatross", beamtrawl, 31 m, USNM-39126 ; 2 females (SL 4.20-4.90 mm), Santa Margarita Island , Baja California, 18 Apr 1889, 24º24’N, 111º53’W, Mexico, R / V "Albatross", 57 m, USNM-110998 ; 1 female (SL 3.80 mm), North Pacific Ocean , off Central California, 37º58’25”N, 122º26’30”W, R / V "Albatross", 05 Mar 1890, beamtrawl, 24 m, USNM-265355 ; 1 male (SL 3.30 mm), 1 female (SL 2.70 mm), off Baja California, 22º52’N, 109º55’W Mexico, R / V "Albatross", 01 May 1882, tangles, 57 m, USNM-265357 ; 1 male (SL 9.40 mm), 1 female (SL 5.30 mm), between Magdalena Bay and Punta Abreojos , Lower California, Mexico, stn. 15, 29 Jan 1971, LACM CR 1971 - 007.1 ; 1 male (SL 8.40 mm), 1 female (SL 7.60 mm), Santa Maria Lagoon , BCS., 24º48’N, 112º16’W, Mexico, 29 Jan 1964, 1.2 m, scuba, SIO C-3610 .

Additional material. (All specimens in holdings of LACM CR) 7 males (SL 4.7–11.0 mm), and 10 females (SL 3.20–6.50 mm), off Santa María Bay, Lower California, Mexico, 24º44’N, 112º14’48’’W, stn. 1031-40, 19 Jan 1940, 33– 46 m, LACM CR 1940 - 003.2 ; 5 males (SL 5.90–16.00 mm), 2 females (SL 5.30– 13.90 mm), 0.9 km SE of Huges Point. Santa María Bay, Lower California , Mexico, 24º44’45’’N, 112º15’25’’W, stn. 1787-49, 04 Apr 1949, 9– 33 m, LACM CR 1949 - 105.2 ; 1 male (SL 5.90 mm), 3 females (SL 5.50–10.40 mm), Magdalena Bay , Lower California, Mexico, 24º24’N, 112º04’W, 02 Jun 1968, R / V "Te Vega", XVIII-23, 3– 8 m, 1968-408.2 ; 1 male (SL 6.80 mm), E. of Cabeza Ballena , Gulf of California, 22º53’50’’N, 109º49’45’’W, stn. 620-37, 03 Mar 1937, 46 m, LACM CR 1937 - 021.1 ; 5 males (SL 3.80–7.00 mm), 4 females (SL 5.20–5.70 mm), 1 ovigerous female (SL 4.3 mm), 2 juvs., SE of Punta Tosca , Lower California, Mexico, stn. 34, 27 m, LACM CR 1971 - 007.2 .

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

Description. Shield ( Fig. 31A) 0.95–1.10 times longer than wide; anterior margin between rostrum and lateral projections shallowly concave; lateral margins convex, somewhat irregular, with tufts of long setae; dorsal face of shield flat, with tufts of long setae; weakly-calcified Y-shaped linea present posteriorly. Rostral lobule weakly produced. Lateral projections produced, bluntly triangular, usually with 1 small marginal spine. Posterior carapace lateral elements well calcified, unarmed. Branchiostegites unarmed.

Ocular peduncles ( Fig. 31A) 0.55–0.58 length of shield, very stout; corneas dilated 1.36 the width of the base of ocular peduncle; corneal length 0.45 of ocular peduncle length. Ocular acicles ( Fig. 31A, B) broad; distal margins each with 5 spines, tips often corneous. Interocular plate with pair of protrusions.

Antenular peduncles ( Fig. 31A) slender; when fully extended exceeding by 1.25–1.50 length of ocular peduncles; ultimate and penultimate segments unarmed; basal segment ( Fig. 31C) with 5 or 6 small spines on ventral margin, 1 small spine at ventromesial distal angle.

Antennal peduncles ( Fig. 31A, D), when fully extended, equaling or slightly overreaching ocular peduncles; fifth segment unarmed; fourth segment with 1 or 2 small spines or spinules dorsodistally; third segment weakly pronounced ventrally, with 1 small subdistal spine; second segment with dorsomesial distal angle bearing 1 spine; dorsolateral angle pronounced, terminating in bifid spine; first segment with ventrolateral distal angle with 1 espine. Antennal acicles ( Fig. 31A, B, D) moderately large, usually reaching basis of corneas, terminating in bifid spines; dorsomesial margin with 6 or 7 corneous-tipped spines; dorsolateral margin with 2 corneous-tipped spines; ventrolateral margin usually with 1 small corneous-tipped spines on middle distal. Antennal flagellum with very short setae on each articulation.

Third maxilliped ( Fig. 31E) with basis-ischium fusion incomplete; coxa with several small spines on ventrolateral distal margin; basis with 2 small, corneous-tipped spines; ischium with well developed crista dentata, ventrolaterodistal margin with 1 spine; merus with 2–4 spines on ventral margin, dorsodistal margin with 1 spine.

Chelipeds vastly unequal, left larger. Left cheliped ( Figs. 32A, 35 Ba, Ca) very stout, 1.40–1.50 times longer than wide, proportion and armature generally similar between males and females. Dactyl terminating in large corneous claw; cutting edge with 5 molar teeth; upper face ( Fig. 32B) with 2 irregular rows of scalelike tubercles fringed distally with small rounded granules and moderately long plumose setae, scales on inner edge usually bearing strong, corneous-tipped spines; outer face with row of strong, rounded spine-like tubercles; inner face with three longitudinal rows of tufts of long setae, upper row also bearing small corneous spines. Fixed finger terminating in large corneous claw; cutting edge with 5 or 6 molar teeth. Outer face ( Fig. 32A) of palm and fixed finger with somewhat irregular transverse rows of scale-like tubercles; larger scales on distal third of palm and fixed finger, each scale fringed distally with 1–9 small rounded granules and moderately long plumose setae, which reach base of next scale; upper margin of palm with row of prominent spines; upper outer surface with 5 or 6 irregular longitudinal rows of rounded spine-like tubercles becoming in scale-like tubercles distally, scales fringed distally with 2–4 rounded granules and plumose setae; lower inner face with numerous flattened tubercles terminating in 1 or 2 rounded spines; lower margin with row of flattened triangularly-shaped corneous spines on distal half ( Fig. 32C). Carpus ( Fig. 32A, D) with upper margin bearing 4 strong, corneous-tipped spines; upper outer face with numerous corneous-tipped spines; lower outer face with small, corneous-tipped spines on proximal and distal margins; ventromesial distal angle usually bearing 4 moderately strong rounded spines. Merus ( Fig. 32D) with distal margin of lateral face bearing several corneous-tipped spines, spines larger on dorsal margin; dorsal face with tufts of long stiff setae; lateral face with flattened tubercles fringed distally with 1 or 2 small corneous spines and tufts of moderately long stiff setae; ventrolateral angle bearing 1 strong corneous-tipped spine; ventromesial margin crested with 6 or 7 rounded spines or teeth, anterior larger than posterior. Ischium with 5 denticles on ventromesial margin.

Rigth cheliped ( Fig. 32E, F) moderately slender, generally setose. Dactyl terminating in large corneous claw; cutting edge with 5 molar teeth; upper face with 3 irregular longitudinal rows of corneous-tipped spines accompanied by tufts of stiff setae; outer face with 1 row of smaller 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 tubercles fringed anteriorly with 1 or 2 small triangularly-shaped corneous spines and 1 very long stiff setae and 1 or 2 very short setae; lower margin ( Fig. 32F) with row of spine-like tubercles terminating in triangle-shaped corneous spines; inner face with several flattened tubercles terminating in 1 or 2 rounded spines; upper face of palm usually with 2 rows of prominent corneous-tipped spines accompanied by tufts of long stiff setae. Carpus with upper face bearing 8 strong, peripherical corneous-tipped conical spines; outer and lower outer faces with corneous-tipped spines. Merus with distal margin of lateral face bearing several corneous-tipped spines, larger spines dorsally; ventrolateral angle with 1 strong corneous-tipped spine; ventromesial margin crested with 6 rounded spines or teeth. Ischium with 5 rounded spines on ventromesial margin.

Second ( Figs. 33A–F, 35 Bc, Cc) and right third ( Fig. 34A–C) pereopods generally similar, but armament of dactyls, propodi and carpi somewhat different between second pair and right third; second pair more slender than right third; of second pair, left slightly shorter than right. Dactyls 1.30–1.50 (second) or 1.40– 1.50 (right third) length of propodi, each terminating in large corneous claw; dorsal faces ( Fig. 33E) each with row of flattened tubercles bearing corneous spines, those on dorsolateral margin larger and tufts of stiff setae, which are denser distally; lateral ( Figs. 33A, 34A) and mesial faces ( Fig. 33C) each with two longitudinal rows of long stiff setae, one in midline and another dorsally, the latter bearing 1 or 2 corneous spines; ventral margin with 5–7 (second) or 1 or 2 (right third) strong corneous spines distally and rows of tufts of stiff setae. Propodi 1.40–1.60 (second) or 1.40–1.50 (right third) length of carpi; dorsal faces flattened and very broad (second, Fig. 33F) or relatively narrower (right third, Fig. 34C), each armed with 3 irregular rows of flattened tubercles bearing 1 or 2 moderately strong corneous-tipped spines accompanied by 1 very long stiff setae and flanked by 2 or more shorter setae, dorsodistal margins with several small corneous spines and long stiff setae; lateral and mesial faces each with 2 rows of tufts of stiff setae, one in midline and another ventrally (right third, Fig. 34B) or one submedian and another ventrally (second, Fig. 33B, D), in the left second pereopod the ventral tufts bear small corneous spines; ventral face each with tufts of long stiff setae. Carpi 0.60–0.70 (second) or 0.80 (right third) length of meri; lateral faces with median face convex bearing weak longitudinal sulcus flanked ventrally with tufts of long stiff setae and corneous spines distally; dorsal margin of second pereopods ( Fig. 33F) with row of corneous-tipped conical spines increasing in size distally and flanked laterally by line of smaller spines, right third pereopod with 2 strong corneous-tipped distally, dorsodistal angle usually bearing 2 small corneous-tipped conical spines. Meri with dorsal face with tufts of long stiff setae; ventral margins with double irregular row of denticles (second) or scarcely small spines or spinules distally (right third) and tufts of long stiff setae, laterodistal angle with 1 corneous-tipped spine.

Left third pereopod ( Figs. 34D, E, 35 Bb, Cb) stout. Dactyl 1.40–1.60 length of propodus, broad, terminating in large corneous claw; lateral face ( Fig. 34D) flattened with a deep longitudinal furrow lined with small flattened tubercles fringed distally with short plumose setae; both sides of furrow with scales, which are fringed distally with small corneous-tipped spines and plumose setae, setae longer toward margins of dactyl; lower lateral edge with strong corneous-tipped spines partially obscured by tufts of long plumose setae and scarce long stiff setae; dorsal face with row of flattened tubercles bearing moderately strong corneous-tipped spines on dorsolateral margin on proximal three-fourths, distal fourth with small corneous spines accompanied by long spine-like stiff setae, and with corneous spines on dorsomesial margin; mesial face ( Fig. 34E) convex, with short longitudinal groove subproximally and 2 rows of tufts of long stiff setae, upper row of tufts usually is accompanied by coeneus spines; ventral face with moderately deep longitudinal furrow, with 2 strong corneous spines distally and tufts of long stiff setae on margins. Propodus 1.30–1.40 length of carpus, very broad; lateral face ( Figs. 34D, 35 Bb, Cb) with longitudinal median ridge strongly pronounced, with transverse scales on both sides of a smooth area; scales fringed distally with small corneous-tipped spines and plumose setae, setae longer toward edges of propodus; scales terminating in strong corneoustipped spines on ventrolateral edge, and in large tubercles bearing 2 strong corneous spines on dorsolateral margin; dorsal face with 2 irregular longitudinal rows of flattened tubercles bearing 1 or 2 moderately strong corneous spines, dorsodistal margin with several small corneous spines and long stiff setae; mesial face ( Fig. 34E) with 2 rows of tufts of stiff setae, one in midline and another near ventral margin, distal margin with 3 or 4 corneous spines. Carpus 0.90 length of merus. Armament and setation of carpus and merus similar to those of right third.

Sternite XII (third pereopods) ( Fig. 31F) with anterior lobe rectangular, bearing a median elongate protuberance with tuft of long setae anteriorly.

Fourth pereopod ( Fig. 31G) subchelate; dactyl with 5–9 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. 33G) with second to fifth left pleopods, fringed with long setae, each with well developed exopod. Female pleon ( Fig. 33H) with second to fifth left pleopods, fringed with long setae; second to fourth triramous; fifth biramous, endopod very small; single, triangular, elongate fleshy membranous fringed with long setae present between fourth and fifth pleopods ( Fig. 33I).

Uropods ( Fig. 33G, H) strongly asymmetrical, left larger than right; endopods and exopods with well developed rasps.

Telson ( Fig. 31H) with lateral constrictions; marginal area partially calcified; posterior lobes separed by median cleft, left larger than right, each with 5 (left) or 4–7 (right) corneous spines and setae of different sizes on terminal margin; anterior lobes with long setae on lateral margins.

Color. In life, unknown.

Etymology. The specific name is derived from the name of the type locality, Magdalena Bay, western coast, Baja California Sur, Mexico.

Distribution. Off Central California, U.S.A., along the western coast of Baja California, and off Cabeza Ballena, Gulf of California, Mexico; 3 to 57 m.

Remarks. Dardanus magdalenensis n. sp. features a unique character that separates it from all other species. The inner lower margin of palm of left cheliped ( Fig. 37L) is only armed on distal half, while the lower margin in the other five species is armed along its entire margin. The sculpture of the left third pereopod dactyl and propodus of D. magdalenensis is similar to that of D. stimpsoni , but setae on ventrolateral and dorsolateral margins of both segments are longer in the former. Moreover, longitudinal median ridge of propodus is more pronounced in D. magdalenensis than in D. stimpsoni and D. janethaigae ( Figs. 36N, 37D, N). Contour of ventral margin of left cheliped is straight in D. magdalenensis ( Fig. 37K) and slightly curved in D. janethaigae and D. pilosus ( Fig. 37A, F), particularly in its proximal part. Dardanus magdalenensis features ocular peduncles and cornea proportionally much longer than D. janethaigae . The antennule is proportionally longer in D. janethaigae ; however, antennal acicles are shorter and do not reach to basis of cornea ( Table 1).