Dardanus umbella, Asakura, Akira, 2006

Asakura, Akira, 2006, Dardanus sanguinocarpus Degener, 1925 (Crustacea: Decapoda: Anomura: Diogenidae) species complex: a redescription of D. sanguinocarpus and descriptions of three new species, Zootaxa 1230, pp. 1-54 : 27-37

publication ID	https://doi.org/ 10.5281/zenodo.172729
DOI	https://doi.org/10.5281/zenodo.6259129
persistent identifier	https://treatment.plazi.org/id/039D87E1-C409-1F62-4B5C-FE41DAAFFDAB
treatment provided by	Plazi
scientific name	Dardanus umbella
status	sp. nov.

Treatment

Dardanus umbella View in CoL sp. nov.

( Figs. 16–22 View FIGURE 16 View FIGURE 17 View FIGURE 18 View FIGURE 19 View FIGURE 20 View FIGURE 21 View FIGURE 22 , 32 View FIGURE 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 View FIGURE 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 View FIGURE 16 A) 0.8–0.9 length of shield, subcylindrical, slightly inflated distally; corneas only very slightly dilated. Ocular acicles ( Fig. 16 View FIGURE 16 B) broad; distal margins each with 2–5 spines, tips often corneous. Interocular plate ( Fig. 16 View FIGURE 16 B) with pair of small protrusions.

Antennular peduncles ( Fig. 16 View FIGURE 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 View FIGURE 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 View FIGURE 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 View FIGURE 16 C, D) with welldeveloped crista dentata ( Fig. 16 View FIGURE 16 D); basis with 1 or 2 corneous spines ( Fig. 16 View FIGURE 16 D).

Chelipeds vastly unequal, left larger. Left cheliped very stout, more elongate in paratype male ( Fig. 17 View FIGURE 17 A, B) than in holotype female ( Fig. 18 View FIGURE 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 View FIGURE 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 View FIGURE 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 View FIGURE 17 ), or numerous prominent calcareous or corneoustipped spines (holotype female, Fig. 18 View FIGURE 18 ). Merus with ventrolateral margin bearing few large spines (paratype male, Fig. 17 View FIGURE 17 ), or ventral margin and ventral 0.3 of lateral face bearing numerous corneous or corneoustipped spines (holotype female: Fig. 18 View FIGURE 18 ); distal margin of lateral face with 0–3 spines. Ischium unarmed.

Right cheliped moderately slender ( Fig. 17 View FIGURE 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 View FIGURE 19 ) and right third ( Fig. 22 View FIGURE 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 View FIGURE 19 C); few strong spinelike setae present dorsodistally ( Figs. 19 View FIGURE 19 D, 22B) or laterally ( Fig. 22 View FIGURE 22 B); lateral and mesial faces generally convex (second, Fig. 19 View FIGURE 19 B, C) or each with longitudinal faint sulcus (third, Fig. 22 View FIGURE 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 View FIGURE 19 E) or 2.2–2.3 (right third, Fig. 22 View FIGURE 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 View FIGURE 19 A) or 0.6–0.7 (right third, Fig. 22 View FIGURE 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 View FIGURE 20 , 21 View FIGURE 21 ) generally very stout. Dactyl ( Figs. 20 View FIGURE 20 A, B, 21A–C) 1.4–1.5 length of propodus, very broad, terminating in strong corneous claw; lateral surface ( Fig. 20 View FIGURE 20 B) with dorsal row of corneous spines ( Fig. 20 View FIGURE 20 Ba), dorsal half with longitudinal concavity ( Fig. 20 View FIGURE 20 Bb), ventral half ( Fig. 20 View FIGURE 20 Bc) with scattered corneous spines or spiniform setae and miniscule setae reminiscent of umbrellalike ribs (not seen in Fig. 20 View FIGURE 20 B due to their tiny size); ventral margin somewhat irregular proximally, with row of small corneous spines ( Fig. 21 View FIGURE 21 C) and rows of stiff setae ( Figs. 20 View FIGURE 20 B, 21B); mesial face ( Fig. 21 View FIGURE 21 B) strongly convex, with few irregular rows of tufts of short stiff setae; dorsal margin ( Fig. 21 View FIGURE 21 B) with rows of dense stiff setae. Propodus ( Figs. 20 View FIGURE 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 View FIGURE 20 Ca), dorsomesial surface of each lobe with 1–3 strong spines and dense setae ( Fig. 21 View FIGURE 21 D); lateral face ( Fig. 20 View FIGURE 20 C) with dorsal half bearing very deep longitudinal concavity ( Fig. 20 View FIGURE 20 Cb) with scattered stiff setae, ventral half with 2–4 irregular rows of large protuberances ( Fig. 20 View FIGURE 20 Cc) each bearing 1 to several stiff setae or spiniform setae and with miniscule setae reminiscent of umbrellalike ribs ( Fig. 20 View FIGURE 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 View FIGURE 20 Cd), ventromesial margin of each lobe ( Fig. 21 View FIGURE 21 E) with 0–2 very large corneous spines and row of setae; mesial face ( Fig. 21 View FIGURE 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 View FIGURE 20 A) with several large corneoustipped spines. Merus and ischium ( Fig. 20 View FIGURE 20 A) with armament and setation similar to those of right third.

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

Fourth pereopod ( Fig. 16 View FIGURE 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 View FIGURE 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 View FIGURE 22 D) markedly asymmetrical, left larger than right; endopods and exopods with welldeveloped rasps.

Telson ( Fig. 16 View FIGURE 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.