Ovatis simplex Ng & Chen 2004, new species
Creators: name: Ng, Peter K. L.
name: Chen, H. - l.
Publisher: name: Zenodo
Year: 2004
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Xanthidae
Ovatis
Ovatis simplex

description: Ovatis simplex, new species
(figures 1–3)
Material examined. HOLOTYPE: male (9.9 x 6.0 mm) (IOCAS N160B-23), station 6225, northern part of Nanhai (= South China Sea), near Hong Kong, 83 m, coll. 12 March 1960. PARATYPE: one male (13.9 x 9.1 mm) (ZRC), station 6206, Q44B-7, northern part of Nanhai (= South China Sea), near Hong Kong, 92 m, coll. 11 April 1959.
Description. Carapace ovate, 1.53–1.65 times broader than long (figure 1a, b); regions poorly defined, cervical groove just discernible, gastric grooves very shallow but discernible; dorsal surface glabrous, finely punctate (figure 1a, b); front gently sinuous from dorsal view; separated into two broad lobes by narrow fissure, lateral lobes not discernible (figure 1a, b); supra- and infraorbital margins entire; external orbital tooth not discernible, anterolateral margin convex, rounded, not cristate, margin appears almost entire although very low indentations hint of three broad lobes; antero- and posterolateral margins clearly demarcated; posterolateral margins gently convex to almost straight; posterior carapace margin gently convex (figure 1a, b). Orbits ovate; eyes well developed, filling orbit; distal part of ocular peduncle unarmed (figures 1a, b, 2a, 3b). Basal antennal segment large, subrectangular, movable, filling orbital hiatus; antennal segments 3–5 progressively smaller, flagellum relatively short, not extending beyond width of orbit (figures 2a, 3b). Antennular fossa broadly ovate, antennules folding transversely (figures 2a, c, 3b). Merus of third maxilliped almost squarish, with shallow submedian depression, anteroexternal angle rounded, not angular (figures 2c, 3a); ischium subrectangular, with submedian oblique sulcus, inner margin gently crenulated; exopod relatively stout, tip almost reaching upper edge of merus, inner margin with subdistal triangular projection, flagellum well developed (figure 3a). Posterior margin of epistome with median part gently sinuous, separated by shallow median fissure, lateral lobes well developed, triangular, prominently projecting into buccal cavity (figures 2a, 3b, c). Endostomial ridges very low, not discernible by naked eye.
Surfaces of chelipeds distinctly punctate but glabrous; outer surface without obvious ridges or crests; fingers shorter than palm (figures 1c, 2b); dorsal margin of dactylus with very low, barely discernible crest; cutting edges with several distinct teeth; inner distal angle of carpus with low, rounded tooth; merus without crests or ridges (figure 2b). Ambulatory legs relatively slender, second pair longest; merus with low but visible crest on dorsal margin, crests on ventral margins low, visible only distally; carpus and propodus without discernible crests; dactylus styliform, flattened laterally (figures 1a, b, 2c, 3e).
Anterior thoracic sternum glabrous, finely granular; sternites 1 and 2 fused, suture not visible; distinct gently sinuous suture (towards buccal cavity) between sternites 2 and 3; suture between sternites 3 and 4 laterally complete, median part just visible, appears incomplete, surface gently depressed; male abdominal cavity reaching imaginary line connecting median part of chelipedal coxae (figures 2c, 3f). Male abdomen occupying entire space between coxae of fourth ambulatory legs, only small part of sternite 8 visible when abdomen closed; segments 3–5 completely fused without trace of sutures, lateral margins gently concave, distal margin ca 0.6 times length of proximal margin; segment 1 slightly longitudinally narrower than segment 2; segment 6 subrectangular, broader than long, lateral margins almost straight; telson triangular, lateral margins gently convex, tip rounded (figure 3d).
G1 relatively stout, gently sinuous, tip directed outwards; distal part dilated, with numerous long setae on distal part (figure 3g –j). G2 short, gently sinuous, about one-third length of G1; distal segment about one-quarter length of basal segment, gently upcurved (figure 3k).
Etymology. The name is derived from the Latin for simple. It is used as a noun in apposition.
Remarks. The two type males agree well in their external morphology, although the carapace of the paratype is proportionately less broad (width to length ratio 1.53 versus 1.65). Both specimens are not in good condition but all the key characters are still observable. Unfortunately, no females are available so their abdominal characters are not known.
Nothing much is known about their biology, both specimens were trawled from medium depth (83 and 92 m) in waters off the northern part of the South China Sea, off Hong Kong.
Comparative material
Liagore rubromaculata: one female (IOCAS), station 6118, Nanhai, coll. 6 April 1960; two males (smaller 10.4 x 7.8 mm) (IOCAS K15513 -39), station 6089, 41 m, Nanhai, coll. 7 April 1960; one male (IOCAS N1698-17), station 6119, 57 m, coll. 6 April 1960; four males, one female (IOCAS K158B-22), station 6075, 39 m, coll. 7 April 1960; 12 males (largest 41.1 x 29.1 mm, smallest 13.1 x 10.3 mm) (one with Sacculina), 12 females (largest 28.9 x 20.8 mm, smallest 12.8 x 9.6 mm) (IOCAS), two males, two females (ZRC), station 6105, 45 m, coll. 4 April 1960; three males (ZRC 1998.215), Tashi Fishing Port, Ilan County, north-eastern Taiwan, coll. P. K. L. Ng, 3–4 August 1996; one male, one female (ZRC 1995.626), northern Taiwan, coll. C. H. Wang, 1990s; one male (ZRC 1970.3.9.3), Keelung, northern Taiwan, coll. Institute of Fisheries Research, 1963; four males, four females (ZRC 1997.744), South China Sea, Tungkang Port, Kaohsiung, south-western Taiwan, coll. P. K. L. Ng, 5 August 1996; seven males, three females (ZRC 2001.96), South China Sea, Tungkang Port, Kaohsiung, south-western Taiwan, coll. P. K. L. Ng, 6 November 2000; one male (ZRC 1984.6405), South China Sea, near Singapore, coll. H. Huat, 16 September 1983; one juvenile male (ZRC 1970.1.11.28), Djalandhi, Java, Indonesia, coll. R. Serène, 1963; one male, one female (ZRC 1995.956), Gulf of Carpentaria, north-western Queensland, Australia, coll. CSIRO ‘ Southern Surveyor’, 21 February 1992.
Liagore erythematica: three males, one female (ZRC 2002.346), Andaman Sea, Pichai Fish Port, Phuket, Western Thailand, coll. J. C. Y. Lai et al., 2–3 September 2001; one female (ZRC 2001.1064), Andaman Sea, Pichai Fish Port, Phuket, Western Thailand, coll. P. K. L. Ng, 17 February 2001; two males, one female (ZRC 1998.1132), Andaman Sea, Pichai Fish Port, Phuket, Western Thailand, coll. S. Chaitiamvong, December 1998; seven males, one female (ZRC 2000.784), Andaman Sea, Pichai Fish Port, Phuket, Western Thailand, coll. N. K. Ng et al., 17–20 January 2000; four males (ZRC 2000.374), Andaman Sea, Pichai Fish Port, Phuket, Western Thailand, coll. P. K. L. Ng, 24 August 1999; 11 males, one female (ZRC 2000.834), Andaman Sea, Pichai Fish Port, Phuket, Western Thailand, coll. P. K. L. Ng, 3–6 May 2000; one male (ZRC 1999.155), Andaman Sea, Pichai Fish Port, Phuket, Western Thailand, coll. P. K. L. Ng, April 1999; one male (ZRC 1998.1236), Ranong, Tubli, Western Thailand, coll. 2 July 1991; one male (ZRC 1992.10520), Andaman Sea, between Penang and Langkawi islands, northern Peninsular Malaysia, coll. C. P. How and C. O. Lau, 12 November 1991.
Pulcratis reticulatus: holotype male (15.1 x 10.6 mm) (ZRC), port at Tung-Kang, Pingtung County, southern Taiwan, commercial inshore trawlers, deep waters (100–400 m depth), coll. S.-H. Lai, 4 August 1996; paratype females [13.8 x 10.2 mm (ovigerous), 13.7 x 10.0 mm] (ZRC), port at Tung-Kang, Pingtung County, southern Taiwan, commercial inshore trawlers, deep waters (100–400 m depth), coll. P. K. L. Ng, 5 August 1996; one male (19.0 x 13.5 mm) (ZRC 1998.459), port at Tung-Kang, Pingtung County, southern Taiwan, commercial inshore trawlers, deep waters (100–400 m depth), coll. M. F. Wu, 5 August 1995; one female (ZRC 2001.165), Tashi Port, Ilan County, north-eastern Taiwan, coll. P. K. L. Ng, May 1997; one female (15.5 x 10.7 mm) (IOCAS L45B), station 6121, South China Sea, 113 m, coll. 12 April 1959.
Paratergatis longimanus: one male (23.2 x 12.8 mm), one female (14.6 x 8.7 mm) (IOCAS L63B), station 6143, South China Sea, 122.5 m, coll. 22 April 1959; one male (ZRC 2002.578), Sa Yu Harbour, Fujian Province, China, coll. S. H. Fan, August 1996; one female (ZRC 1998.47), Tashi Port, Ilan County, north-eastern Taiwan, coll. M. S. Jeng, 26 November 1997.
description: Published as part of Ng, Peter K. L. & Chen, H. - l., 2004, On a new genus and new species of xanthid crab (Crustacea, Decapoda, Brachyura, Xanthinae) from the South China Sea, with notes on the genus Liagore De Haan, 1833, pp. 2345-2360 in Journal of Natural History 38 (18) on pages 2357-2359, DOI: 10.1080/00222930310001647352, http://zenodo.org/record/5250420