Lyphira acutidens ( Chen, 1987 )

Rahayu, Dwi Listyo & Ng, Peter K. L., 2024, On the genus Lyphira Galil, 2009 (Crustacea: Brachyura: Leucosiidae), with descriptions of four new species from the West Pacific, Zootaxa 5476 (1), pp. 358-392 : 364-368

publication ID	https://doi.org/ 10.11646/zootaxa.5476.1.29
publication LSID	lsid:zoobank.org:pub:DD4EA1FE-A0BE-4BA4-9AD3-E460B131C518
DOI	https://doi.org/10.5281/zenodo.12681459
persistent identifier	https://treatment.plazi.org/id/03DD87DA-FFB8-124E-28EE-FBBC87BE1EA1
treatment provided by	Plazi
scientific name	Lyphira acutidens ( Chen, 1987 )
status

Treatment

Lyphira acutidens ( Chen, 1987) View in CoL

( Figs. 3D View FIGURE 3 , 6B View FIGURE 6 , 7D View FIGURE 7 , 9B View FIGURE 9 , 10C View FIGURE 10 , 11C View FIGURE 11 , 13B, C View FIGURE 13 , 14B View FIGURE 14 , 15D View FIGURE 15 , 16C View FIGURE 16 , 17H–L View FIGURE 17 , 21B View FIGURE 21 )

Phylira acutidens Chen, 1987: 201 , fig. 1; Chen & Sun 2002: 381, text fig. 170, pl. 15.1; Ng et al. 2008: 93.

Lyphira heterograna View in CoL .— Galil, 2009: 300 View Cited Treatment (part). (not Philyra heterograna Ortmann, 1892 View in CoL ).

Material examined. 1 male (8.9 × 8.6 mm), 1 female (13.4 × 12.9 mm), ZRC 2002.0504 View Materials , station 4027, Yellow Sea, coll. Institute of Oceanography , Chinese Academy of Science, 9 December 1958 .

Diagnosis. Carapace slightly broader than long, dorsal surface of carapace covered with closely spaced minute granules, hepatic and intestinal regions with larger, more prominent granules ( Figs. 3D View FIGURE 3 , 6B View FIGURE 6 ). Frontal margin granulated, postfrontal lobe slightly convex ( Figs. 11C View FIGURE 11 , 13B, C View FIGURE 13 ). Endostomial spine absent ( Figs. 13B, C View FIGURE 13 , 14B View FIGURE 14 ). Lateral and posterolateral margin of carapace with row of small granules interspersed by several larger granules ( Fig. 3D View FIGURE 3 , 6B View FIGURE 6 ); posterior carapace margin gently concave with row of larger granule, medially slightly produced ( Figs. 3D View FIGURE 3 , 10C View FIGURE 10 ). Third maxilliped exopod 2.9 times as long as broad, as broad as basal part of endopod, forming petaliform structure with convex outer margin, endopod with completely fused basis-ischium, as long as merus, with shallow submarginal sulcus near inner margin ( Figs. 11C View FIGURE 11 , 17H View FIGURE 17 ). Chelipeds subequal; merus, carpus and chela surfaces smooth or covered by closely spaced, small rounded granules ( Figs. 3D View FIGURE 3 , 6B View FIGURE 6 ); chela stout, fingers longer than length of palm, surface with longitudinal sulcus flanked by row of granules; pollex slightly bent, cutting edge lined with denticles; dactylus 1.2 times as long as palm along upper margin, row of small granules on upper margin, cutting edge with median large tooth lined with denticles, remaining of edge with small denticles ( Fig. 15D View FIGURE 15 ). P2–P5 slender, short; merus distinctly longer than carpus and propodus; dactylus longer than propodus, lanceolate, terminating in corneous tips ( Figs. 3D View FIGURE 3 , 6B View FIGURE 6 ); fourth leg shortest with merus 4.1 times as long as broad, margins lined with small granules, more prominent on ventral margin ( Fig. 16C View FIGURE 16 ). Thoracic sternites transversely narrow, surface finely granulated, larger granules laterally ( Fig. 7D View FIGURE 7 ). Sternopleonal cavity deep, reaching to proximal distance between fused thoracic sternites 1–3. Pleon narrow, somites 2–6 fused, somite 6 longitudinally subrectangular, surface with one low granule medially, lateral margins gently convex; telson triangular ( Figs. 7D View FIGURE 7 , 17I View FIGURE 17 ). G1 elongate, slender, same size from proximal to distal area; distal process bilobed, tip rounded ( Fig. 17J‒L View FIGURE 17 ). Female pleon broad, convex, smooth, somites 2‒6 fused, suture between somites 2 and 3; telson as long as its basal width ( Fig. 9B View FIGURE 9 ); vulvae positioned closer to median part of sternite 6, each opening prominently crescent-shaped, relatively long, without opercular cover ( Fig. 21B View FIGURE 21 ).

Colour. Not known.

Remarks. Chen (1987) described Philyra acutidens from a large series of specimens from the East China Sea and Yellow Sea (87 males and 101 females), and she compared it with P. heterograna , noting that it can be distinguished by its slightly smaller adult size (largest carapace length 16.5 mm versus 18.5 mm), slightly longer carapace, the presence of more granules on the carapace, the third maxilliped exopod is slightly narrower, the proportionately shorter fingers of the chela, the cutting margin of the fingers lacking a large tubercle, male pleonal somite 6 with median tooth, and the female telson is longer than broad. She figured a specimen of what she regarded was L. heterograna s. str. ( Chen 1987: fig. 2) but did not state where it was from. From her figures, Chen’s (1987: fig. 2) “ Philyra heterograna ” agrees well with L. heterograna s. str. as defined here.

Galil (2009) commented that L. acutidens is a junior synonym of L. heterograna , arguing the differences observed were only due to their subadult nature. This is not the case; the species is not small, with the holotype male measuring 15.0 × 16.0 mm and allotype female 11.9 × 12.0 mm. The present male specimen (ZRC 2002.0504) is relatively small (8.9 × 8.6 mm) and does not appear fully adult; but the slightly larger female (13.4 × 12.9 mm) has the pleon round and domed and is clearly adult. Their characters, however, agree in most aspects with Chen’s (1987) detailed descriptions and figures.

We are of the opinion the two species are distinct. The differences in the adult size observed by Chen (1987) are actually not significant, and carapace proportions alone is not enough to justify recognizing two species. The authors have on hand two non-type topotypic specimens from the Yellow Sea but are part of Chen’s (1987) original series, and they do show the other differences highlighted by her. Most marked are the denser concentration of granules on the dorsal surface. The median tubercle on male pleonal somite 6 of L. acutidens is slightly sharper than those of L. heterograna and is slightly more subdistal in position, just behind the distal margin ( Figs. 7D View FIGURE 7 , 17I View FIGURE 17 ) whereas in L. heterograna , it is positioned a bit further back ( Figs. 7A‒C View FIGURE 7 , 17B View FIGURE 17 ). Chen’s (1987) figure of the male pleon is slightly inaccurate, the median tubercle on somite 6 is not distal in position ( Chen 1987: fig. 1.3) but is actually subdistal. Also significant is that the vulvae are differently structured, with the opening in L. heterograna is short and weakly crescent-shaped ( Fig. 21A View FIGURE 21 ) whereas it is slit-like and distinctly more crescent-shaped in L. acutidens ( Fig. 21B View FIGURE 21 ). As such, we believe it is better to recognize L. acutidens as a distinct species for now.