Parasesarma carolinense ( Rathbun, 1907 )

Ng, Peter K. L., Davie, Peter J. F. & Li, Jheng-Jhang, 2016, On the identities of Parasesarma carolinense (Rathbun, 1907) and Parasesarma sigillatum (Tweedie, 1950), with description of a new species from Taiwan (Crustacea: Brachyura: Sesarmidae), Raffles Bulletin of Zoology 64, pp. 257-268 : 259-261

publication ID

https://doi.org/ 10.5281/zenodo.5355307

publication LSID

lsid:zoobank.org:pub:88473619-8A6C-4951-AD3C-89C14653CAC3

DOI

https://doi.org/10.5281/zenodo.5452585

persistent identifier

https://treatment.plazi.org/id/84169C56-9353-FFD1-2BF6-9DC3FE6E09BD

treatment provided by

Valdenar

scientific name

Parasesarma carolinense ( Rathbun, 1907 )
status

 

Parasesarma carolinense ( Rathbun, 1907) View in CoL

( Figs. 2 View Fig ; 5A–C View Fig ; 6A–F View Fig )

Sesarma (Parasesarma) carolinensis Rathbun, 1907: 34 View in CoL , pl. 5 fig.

2, 2a; pl. 9 fig. 1; Tesch, 1917: 141; Serène, 1968: 108. Parasesarma carolinense View in CoL – Ng et al., 2008: 222 (list, part).

Material examined. Holotype: male (9.2 × 7.0 mm) ( USNM 32861 About USNM ), Kusaie, Carolines, coll. 9 February 1900.

Diagnosis. Carapace 1.31 times broader than long; lobes of frontal margin separated by broad, very shallow concavity ( Fig. 2A–C View Fig ); upper surface of cheliped palm with 2 transverse pectinate crests, primary (distalmost) consisting of row of 14 or 15 tall pectinate teeth, tip of each tooth gently curved, secondary crest with 16 or 17 relatively lower pectinate teeth ( Fig. 2F, I View Fig ); inner surface of palm with short obliquely transverse granulated ridge on upper half ( Fig. 2G View Fig ); dorsal surface of dactylus with 15 or 16 triangular tubercles, each dactylar tubercle with distinct transverse ridge ( Fig. 2F, G, I View Fig ); inner distal margin of lamelliform process of merus lined with sharp triangular teeth ( Fig. 2F, G View Fig ); ambulatory legs short, stout; merus of third leg 2.0 times as long as wide; upper margin of merus with subdistal spine; propodus of third leg 2.7 times as long as wide; dactylus of third and fourth legs 0.7 and 0.8 times length of propodus, respectively ( Figs. 2A View Fig ; 5A–C View Fig ); male telson triangular with strongly convex lateral margins, ca. 1.5 times length of pleonal somite 6 ( Fig. 6B View Fig ); G1 relatively slender, straight; apical process bent to form an angle of about 80º from the vertical, chitinous distal part long ( Fig. 6C–F View Fig ).

Description. Carapace trapezoidal, 1.31 times broader than long; dorsal surfaces relatively smooth, glabrous; regions poorly defined, separated by shallow grooves except for deeper H-shaped median gastric groove; lateral parts of dorsal carapace surface with distinct oblique striae; posterior surface with short transverse striae; lateral margins with numerous tufts of short setae ( Fig. 2A, B View Fig ). Postfrontal region distinct, low, rounded, not cristate, separated into 4 lobes by narrow, distinct longitudinal grooves; median lobes approximately same width as lateral lobes ( Fig. 2A–C View Fig ). Front truncate, distinctly deflexed downwards, margin weakly bilobed from dorsal view with lobes separated by broad, very shallow median concavity; confluent with supraorbital margin ( Fig. 2A–C View Fig ). Supraorbital margin entire, posteriorly oblique, convex along anterior half, posterior half gently sinuous ( Fig. 2A, B View Fig ). External orbital tooth triangular, directed obliquely outwards, representing point of greatest carapace width; antero- and posterolateral margins not demarcated, without trace of tooth or indentation, lateral margins straight, converging to meet weakly convex posterior carapace margin ( Fig. 2A, B View Fig ). Eyes with large cornea, not reaching to external orbital tooth ( Fig. 2A, B View Fig ). Antennal and antennular basal segments adjacent, not separated by septum; basal antennular segment large; antennal flagellum relatively long, entering orbit.

Third maxilliped with ischium relatively short, subrectangular in shape, with shallow median sulcus, left one relatively shorter than right one (see Remarks) ( Figs. 2E View Fig ; 6A View Fig ); merus subovate, with distinct submedian ridge; inner margin of merus-ischium with stiff setae; exopod slender, tip reaching about half length of outer margin of merus, flagellum long ( Figs. 2D, E View Fig ; 6A View Fig ).

Chelipeds relatively stout in adult male, symmetrical ( Fig. 2A View Fig ). Merus short, inner distal part prominently carinate, forming large lamelliform structure; distal margin of lamelliform structure appears serrated, with short sharp teeth, inner margin with denticles; outer margin uneven or with low granules; outer surface with dorsal striation; inner surface gently concave, smooth, with 2 rows of setae ( Fig. 2A, F, G View Fig ). Carpus with inner angle not produced, rounded; outer margin and surface striated ( Fig. 2F, G View Fig ). Upper surface of palm with 2 obliquely transverse pectinate crests, primary (distalmost) crest with row of 14 or 15 tall pectinate teeth, tip of each tooth gently curved, secondary crest with 16 or 17 relatively lower pectinate teeth ( Fig. 2F, I View Fig ). Outer surface of palm with striations and punctations; inner surface of palm with short oblique granulated crest on upper part ( Fig. 2H View Fig ). Fingers short, subequal to length of palm; cutting edge of pollex with large, rounded teeth on distal half, teeth on proximal part relatively lower, tip excavated, spatulate; dactylus with rounded tooth on subproximal part of cutting margin, rest of margin with small teeth, tip excavated, spatulate; dorsal surface of dactylus with 15 or 16 triangular tubercles, gradually sloping distally, becoming lower, each tubercle with a strong proximal transverse ridge ( Fig. 2F–I View Fig ).

Ambulatory legs short, stout, laterally flattened; second and third pairs longest ( Fig. 2A View Fig ). Merus with low transverse striae on upper surface, meri of second and third legs 2.2 and 2.0 times as long as wide, respectively; upper margin of merus with subdistal spine ( Figs. 2A View Fig ; 5A–C View Fig ). Carpus with 2 accessory carinae on outer surface. Propodus of third leg ca. 2.7 times as long as wide with low carina on inferior proximal portion of outer surface, dorsal and ventral margins with short stiff setae ( Figs. 2A View Fig ; 5A–C View Fig ). Dactylus of third and fourth legs 0.7 and 0.8 times length of propodus, respectively, tip gently curved distally, terminating in acute calcareous tip, dorsal and ventral margins with short stiff setae ( Figs. 2A View Fig ; 5B, C View Fig ).

Surface of thoracic sternites 1–4 smooth; sternites 1–3 completely fused, without trace of sutures; separated from sternite 4 by deep suture ( Fig. 2D View Fig ). Male sternopleonal cavity reaching suture between sternites 3, 4. Male pleon relatively broad, all somites free; telson triangular with strongly convex lateral margins, ca. 1.5 times length of pleonal somite 6; somite 6 almost twice as wide as long, lateral margins strongly convex; somites 3–5 progressively more trapezoidal; somites 1, 2 very narrow longitudinally; reaching coxa of fourth ambulatory leg, sternite 8 completely covered ( Fig. 6B View Fig ).

G1 relatively slender, straight; apical process bent to form an angle of about 80° from the vertical, chitinous distal part long, aperture terminal ( Fig. 6C–F View Fig ). G2 short, about a third length of G1.

Colour in life. Not known.

Habitat. Not known.

Remarks. The left third maxilliped ( Fig. 6A View Fig ) appears to be abberant, with the ischium relatively short. On the right third maxilliped, the ischium is proportionately longer ( Fig. 2E View Fig ). The right third maxilliped structure of P. carolinense agrees well with those of P. sigillatum and P. corallicum ( Fig. 6G, N View Fig ), respectively.

The species is known only from the holotype specimen. Comparisons with P. sigillatum and P. corallicum n. sp. are provided in the Discussion.

Kingdom

Animalia

Phylum

Arthropoda

Class

Malacostraca

Order

Decapoda

Family

Sesarmidae

Genus

Parasesarma

Loc

Parasesarma carolinense ( Rathbun, 1907 )

Ng, Peter K. L., Davie, Peter J. F. & Li, Jheng-Jhang 2016
2016
Loc

Sesarma (Parasesarma) carolinensis

Rathbun MJ 1907: 34
1907
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