Dardanus umbella sp. nov.

(Figs. 16–22, 32)

Material examined

Holotype: Ψ, SL 5.8 mm, Y­48B, Yap Island, Caroline Islands, Micronesia, 1953, coll. R. Hiatt, JF 1000, USNM 1086590. Paratype: ♂, SL 3.7 mm, 119°50.30’ E, 4°58.20’ N, 2.7 m, st. D5165, Tawi Tawi Group, Sulu Archipelago, Philippine Islands, 24 Feb. 1908, Johnston oyster dredge, R/V Albatross, JF 0186c, USNM 1086591.

Description

Shield (Fig. 16 A) as long as broad; anterior margin between rostral lobe and lateral projections nearly straight; lateral margins slightly convex, somewhat irregular, with rows of long setae. Dorsal surface of shield with short rows or tufts of setae; weakly­calcified Yshaped linea present posteriorly; gastric pits distinct. Rostral lobe indistinct. Lateral projections large, bluntly triangular, produced. Posterior carapace lateral elements well calcified, unarmed. Branchiostegites unarmed.

Ocular peduncles (Fig. 16 A) 0.8–0.9 length of shield, subcylindrical, slightly inflated distally; corneas only very slightly dilated. Ocular acicles (Fig. 16 B) broad; distal margins each with 2–5 spines, tips often corneous. Interocular plate (Fig. 16 B) with pair of small protrusions.

Antennular peduncles (Fig. 16 A) slender, when fully extended, distal margins of ultimate segments reaching bases to distal margins of corneas; ultimate and penultimate segments unarmed; basal segment with ventromesial distal angle bearing small spine.

Antennal peduncles (Fig. 16 A, B), when fully extended, reaching bases of corneas; fifth and fourth segments unarmed; third segment projecting ventrodistally; second segment with dorsomesial distal angle bearing spine, dorsolateral distal angle produced, terminating in simple or bifid spine; first segment with ventrolateral distal angle with spine. Antennal acicle (Fig. 16 B) terminating in strong spine; dorsomesial margin with 2–4 spines; dorsolateral margin with 0–2 subdistal spines. Antennal flagella sparsely setose.

Third maxilliped (Fig. 16 C, D) with well­developed crista dentata (Fig. 16 D); basis with 1 or 2 corneous spines (Fig. 16 D).

Chelipeds vastly unequal, left larger. Left cheliped very stout, more elongate in paratype male (Fig. 17 A, B) than in holotype female (Fig. 18). Dactyl terminating in large corneous claw; cutting edge with 6–10 variously­sized calcareous teeth; upper and outer faces with unarmed to armed with several corneous, or sometimes corneous­tipped, conical spines and short stiff setae. Fixed finger terminating in large corneous claw; cutting edge with 5–8 variously sized calcareous teeth. Palm and fixed finger with outer face bearing numerous prominent corneous­tipped, conical spines, sometimes forming longitudinal rows, and stiff setae of short to medium length; lower half of outer face concave, numerous miniscule setae reminiscent of umbrella­like ribs (Fig. 18 C) present on lower half of outer face; lower face with 1–3 irregular rows of prominent tricolored conical spines each consisting of distal corneous, middle half corneous, and proximal calcareous portions (Fig. 18 B), accompanied with 1–3 irregular rows of corneous or corneous­tipped spines; upper face of palm with 1 or 2 irregular rows of prominent calcareous or corneous­tipped, conical spines. Carpus with upper margin bearing 1 or 2 irregular rows of prominent calcareous or corneous­tipped conical spines; outer face with numerous tubercles (paratype male, Fig. 17), or numerous prominent calcareous or corneous­tipped spines (holotype female, Fig. 18). Merus with ventrolateral margin bearing few large spines (paratype male, Fig. 17), or ventral margin and ventral 0.3 of lateral face bearing numerous corneous or corneous­tipped spines (holotype female: Fig. 18); distal margin of lateral face with 0–3 spines. Ischium unarmed.

Right cheliped moderately slender (Fig. 17 C–E), generally setose. Dactyl terminating in large corneous claw; cutting edge with 5–8 variously­sized calcareous teeth; upper face with 1–3 irregular rows of prominent corneous, or sometimes corneous­tipped, spines; outer face with few corneous spines. Fixed finger terminating in large corneous claw; cutting edge with 5–8 variously­sized calcareous teeth. Palm and fixed finger with outer faces bearing numerous corneous, or sometimes corneous­tipped, spines, often forming longitudinal rows; lower face with 1 or 2 irregular rows of prominent conical spines accompanied with 1–3 irregular rows of corneous, or corneous­tipped spines; upper margin of palm with 1 or 2 irregular rows of very strong corneous­tipped conical spines. Carpus with upper margin bearing 1 or 2 irregular rows of very strong corneous­tipped conical spines; outer face with several, prominent corneous­tipped spines on upper half and many small corneous­tipped spines near distal margin. Merus with distal half of lateral face bearing many corneous or corneous­tipped spines, sometimes forming short transverse row. Ischium unarmed.

Second (Fig. 19) and right third (Fig. 22 A–C) pereopods generally similar, but armament and proportion somewhat different between second pair and right third; second pair more slender than right third; of second pair, left slightly shorter than right. Dactyls of second pair and right third all 1.2–1.3 length of propodi, each terminating in strong corneous claw; dorsal surfaces with irregular rows of tufts of stiff setae, and, on second, setae sometimes forming short obliquely transverse rows (Fig. 19 C); few strong spine­like setae present dorsodistally (Figs. 19 D, 22B) or laterally (Fig. 22 B); lateral and mesial faces generally convex (second, Fig. 19 B, C) or each with longitudinal faint sulcus (third, Fig. 22 B, C), with few longitudinal rows of tufts of stiff setae; ventral margins each with row of 3–6 corneous spines. Propodi 1.7–1.8 (second, Fig. 19 E) or 2.2–2.3 (right third, Fig. 22 A) length of carpi; dorsal faces flat and broad (second) or comparatively narrower (right third), armed with numerous (second) or comparatively fewer numbers of (right third) corneous spines and with long stiff setae, dorsodistal margins armed with corneous spines; lateral faces with few longitudinal rows of tufts of stiff setae. Carpi 0.5–0.6 (second, Fig. 19 A) or 0.6–0.7 (right third, Fig. 22 A) length of meri; dorsolateral and dorsal margins with several corneous­tipped spines distally and large dorsodistal spine (second), or with only large dorsodistal spine (right third). Meri with ventrolateral distal angles each with sharp spine and ventral margins each with row of several spines (second), or meri unarmed (right third). Ischia unarmed.

Left third pereopod (Figs. 20, 21) generally very stout. Dactyl (Figs. 20 A, B, 21A–C) 1.4–1.5 length of propodus, very broad, terminating in strong corneous claw; lateral surface (Fig. 20 B) with dorsal row of corneous spines (Fig. 20 B­a), dorsal half with longitudinal concavity (Fig. 20 B­b), ventral half (Fig. 20 B­c) with scattered corneous spines or spiniform setae and miniscule setae reminiscent of umbrella­like ribs (not seen in Fig. 20 B due to their tiny size); ventral margin somewhat irregular proximally, with row of small corneous spines (Fig. 21 C) and rows of stiff setae (Figs. 20 B, 21B); mesial face (Fig. 21 B) strongly convex, with few irregular rows of tufts of short stiff setae; dorsal margin (Fig. 21 B) with rows of dense stiff setae. Propodus (Figs. 20 C, D, 21D, E) 1.5–1.6 length of carpus, very broad; dorsal margin with series of furrows producing row of lobes, lateral face of each lobe sometimes armed dorsodistally with slender corneous spines or spinelike setae (Fig. 20 C­a), dorsomesial surface of each lobe with 1–3 strong spines and dense setae (Fig. 21 D); lateral face (Fig. 20 C) with dorsal half bearing very deep longitudinal concavity (Fig. 20 C­b) with scattered stiff setae, ventral half with 2–4 irregular rows of large protuberances (Fig. 20 C­c) each bearing 1 to several stiff setae or spiniform setae and with miniscule setae reminiscent of umbrella­like ribs (Fig. 20 D); ventral margin with series of deep furrows producing row of large lobes, lateral face of each lobe with marginal setae or spine­like setae (Fig. 20 C­d), ventromesial margin of each lobe (Fig. 21 E) with 0–2 very large corneous spines and row of setae; mesial face (Fig. 21 A, E) strongly convex, with few rows of tufts of short setae, distal margin with 1–6 corneous spines. Carpus 0.7–0.8 length of merus; lateral face (Fig. 20 A) with several large corneous­tipped spines. Merus and ischium (Fig. 20 A) with armament and setation similar to those of right third.

Sternite of third pereopods with anterior lobe (Fig. 16 E) rectangular, with small protrusion bearing short transverse row of setae.

Fourth pereopod (Fig. 16 F) semichelate; dactyl with 5 or 6 short corneous spines on lateral face ventrally; propodal rasp well developed; carpus with sharp corneous­tipped dorsodistal spine.

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

Female pleon (Fig. 22 D) with second to fifth left pleopods, fringed with setae; second to fourth large, triramous; fifth small, with slender exopod; extremely large fleshy membranous protuberance with scattered setae present between fourth and fifth pleopods. Pleon of paratype male missing.

Uropods (Fig. 22 D) markedly asymmetrical, left larger than right; endopods and exopods with well­developed rasps.

Telson (Fig. 16 G, H) with lateral constrictions; marginal area partially calcified; posterior lobes separated by median cleft, left larger than right, with 5–7 (right) or 9–13 (left) ventral corneous spines near terminal margin, spines on left sometimes very long, terminal margins fringed with many short bristle­like setae and several long setae.

Color in life

Unknown

Remarks

The specimens of this species in USNM were initially identified as Dardanus cf. sanguinocarpus by J. Forest, suggesting that he had already recognized morphological differences between D. sanguinocarpus and this species.