Ovilyra, Ng, 2021

Ng, Peter K. L., 2021, Ovilyra, a new genus of leucosiid crab (Crustacea: Decapoda: Brachyura) from the West Pacific, Zootaxa 4952 (2), pp. 369-380 : 370-371

publication ID	https://doi.org/ 10.11646/zootaxa.4952.2.9
publication LSID	lsid:zoobank.org:pub:28006273-1456-47EC-8888-17CAB686C99F
DOI	https://doi.org/10.5281/zenodo.4695028
persistent identifier	https://treatment.plazi.org/id/03ED87AC-FF9F-FFBE-FF2D-FF4F82BF49FD
treatment provided by	Plazi
scientific name	Ovilyra
status	gen. nov.

Treatment

Ovilyra View in CoL n. gen.

Type species. Philyra fuliginosa Targioni-Tozzetti, 1877 View in CoL , by present designation.

Diagnosis. Carapace longitudinally ovate, distinctly longer than wide (length to width ratio 1.17–1.26); dorsal surface smooth, covered with minute to small granules and small depressions ( Figs. 1A, B View FIGURE 1 , 2A, B View FIGURE 2 , 3A–C View FIGURE 3 ); frontal region not produced anteriorly, with shallow median longitudinal depression; frontal margin granulated, with low median triangular tooth ( Figs. 1B View FIGURE 1 , 2B View FIGURE 2 , 5D, E View FIGURE 5 , 7A, D View FIGURE 7 ); hepatic facet well defined by rows of granules and cristae, elongate, distal part of lower margin prominently angular, with broad tooth on distal one-third ( Figs. 1B, D View FIGURE 1 , 2B, D View FIGURE 2 , 4A View FIGURE 4 ); posterolateral margin demarcated from posterior margin by lobiform tooth ( Figs. 1A, B View FIGURE 1 , 2A, B View FIGURE 2 , 3A–C View FIGURE 3 , 7A, D View FIGURE 7 ); third maxilliped exopod wider than basal part of endopod ( Figs. 1C View FIGURE 1 , 2C View FIGURE 2 , 3E View FIGURE 3 , 5A–C View FIGURE 5 ); endopod with basis-ischium longer than acutely triangular merus ( Figs. 1C View FIGURE 1 , 2C View FIGURE 2 , 3E View FIGURE 3 , 5A–C View FIGURE 5 ); cheliped merus subcylindrical, symmetrical along entire length, chela stout, pollex bent at angle of 45–60º along longitudinal axis, cutting edge of pollex with broad, large subproximal tooth lined with denticles, that of dactylus with subproximal concavity lined with denticles ( Figs. 1A View FIGURE 1 , 2A View FIGURE 2 , 3A–C View FIGURE 3 ); P2–P5 slender, short, merus unarmed ( Figs. 1A, F View FIGURE 1 , 2A, F View FIGURE 2 ); male thoracic sternite 8 visible when pleon closed, between margins of somites 2 and 3 ( Fig. 4B View FIGURE 4 ); sternopleonal cavity deep, reaching to mid-distance between fused thoracic sternites 1–3 ( Figs. 1E View FIGURE 1 , 2E View FIGURE 2 , 4A View FIGURE 4 ); male pleon narrow, with somites 1 and 2 free, somite 1 longitudinally narrow, somite 2 yoke-like, reaching coxae of fourth ambulatory leg ( Figs. 1E View FIGURE 1 , 2E View FIGURE 2 , 4B View FIGURE 4 , 5F, G View FIGURE 5 ), somites 3–6 fused, forming elongate trapezoidal plate, surface smooth, unarmed ( Figs. 3D View FIGURE 3 , 4B View FIGURE 4 , 5F, G View FIGURE 5 ), somite 6 longitudinally subrectangular, free, surface unarmed ( Figs. 1E View FIGURE 1 , 2E View FIGURE 2 , 3D View FIGURE 3 , 4A View FIGURE 4 , 5F, G View FIGURE 5 ), telson triangular, longer than wide ( Figs. 1E View FIGURE 1 , 2E View FIGURE 2 , 3D View FIGURE 3 , 4A View FIGURE 4 , 5F, G View FIGURE 5 ); G1 elongate, slender, distal quarter sharply bent backwards 120–150º from the longitudinal axis; with curved, tapering subdistal process, outer margin lined with 1 or 2 rows of 5–8 elongate spines, distal projection elongate, curved, hook-shape, reaches to, overlaps or overreaches shaft, opening distal ( Fig. 6A–C, E–G, I–K View FIGURE 6 ); G2 short, ca. one-third length of straight part of G1, apex subspatuliform ( Fig. 6D, H, L View FIGURE 6 ); female pleon longitudinally ovate, somites 1 and 2 free, somites 3–6 completely fused to form domed plate ( Fig. 7B, E View FIGURE 7 ); vulvae large, obliquely ovate, on anterior part of sternite 6, without sternal vulvar cover ( Fig. 7C, F View FIGURE 7 ).

Etymology. The genus name is derived from the Latin “ovalis” for oval, in arbitrary combination with the suffix of the genus name Philyra . Gender feminine.

Remarks. In Galil’s (2009) revision of Philyra Leach, 1817 , the articulation of the first two male pleonal somites is a major generic character, separating Philyra s. str., Afrophila Galil, 2009 , Atlantolocia Galil, 2009 , and Ryphila Galil, 2009 , from other genera. With regards to this character, Philyra fuliginosa Targioni-Tozzetti, 1877 (and its junior synonym, P. olivacea Rathbun, 1909 , see below), clearly belongs with the species in this group of genera. Philyra fuliginosa can, however, be immediately distinguished by its carapace being distinctly longer than wide (length to width ratio 1.17–126); the others being all wider than long or at most subequal. The lobiform tooth present at the junction between the posterolateral and posterior carapace margins ( Figs. 1B View FIGURE 1 , 2B View FIGURE 2 ) is diagnostic for P. fuliginosa , a feature absent in the other genera ( Galil 2009: figs. 1A, 4A, 5A, 22A; Galil & Ng 2015: fig. 9A, B). Afrophila and Ryphila have visible hepatic facets ( Galil 2009: figs. 4A, 22A; Galil & Ng 2015: fig. 9A, B) but these are short compared to those in P. fuliginosa ( Figs. 1B, D View FIGURE 1 , 2B, D View FIGURE 2 ), and the ventral margins do not have a distal submedian lobe; Philyra and Atlantolocia have no clear hepatic facets ( Galil 2009: figs. 1A, 5A). The cutting edge of the fingers of the chelae are distinctively structured in P. fuliginosa , with a subproximal lobe present on the pollex which fits into a concavity on the opposing cutting edge of the dactylus ( Figs. 1A View FIGURE 1 , 2A View FIGURE 2 ). Such a structure is present in Philyra ( Galil 2009: fig. 1A), but absent or indistinct in the other three genera ( Galil 2009: figs. 4A, 5A, 22A; Galil & Ng 2015: fig. 10A). The narrow and slender male pleon of P. fuliginosa ( Fig. 5F, G View FIGURE 5 ) is very different from the proportionately more triangular structures of Philyra , Afrophila or Ryphila where somite 3 is proportionately wider ( Galil 2009: figs. 1B, 4B, 22B), and in Atlantolocia , the pleon is wider and subrectangular in shape ( Galil 2009: fig. 5B). The strongly bent distal quarter of the G1 with the presence of a long subdistal process is also a character unique to P. fuliginosa ( Fig. 6A, E, I View FIGURE 6 ) and is not shared by these genera; all of which have straight or almost straight G1 structures (e.g., Galil 2009: figs. 2A–E, 21). In fact, none of the genera which have been previously associated with Philyra have such a strongly bent G1. As such, we here establish a new genus, Ovilyra , for Philyra fuliginosa .

In describing Philyra alcocki from Lake Chilka in eastern India, Kemp (1915: 214, 215) commented that his species was closest to P. olivacea and to a lesser degree to P. fuliginosa . Although the carapace shape and features are superficially similar, P. alcocki is probably not congeneric with P. fuliginosa as its carapace is only slightly longer than wide, being almost round, the male thoracic sternum is proportionately much wider, male pleonal somites 1–5 are fused (although sutures between somites 1–3 are still visible) with somite 3 very wide, giving the male pleon a distinctly triangular shape ( Kemp 1915: 214, fig. 2, pl. 12 fig. 2). In Ovilyra species, the carapace is longitudinally ovate and much longer than wide, the male thoracic sternum proportionately narrow and male pleonal somite 3 is only slightly wider than the other somites, with the male pleon not obviously triangular in shape. “ Philyra ” alcocki will need to be re-examined to ascertain its generic position.

Ovilyra is monotypic for the time being.