Original description. "Body oblong, somewhat convex, black and shining; tibiae, tarsi and antennae reddish brown. Body length (male, n=2; female, n=1), PPL (= length between anterior angles of pronotum and apex of pygidium), male, 4.19 - 4.41 mm, female, 4.97 mm; PEL (= length between anterior angles of pronotum and apices of elytra), male, 3.61 - 4.19 mm, female 4.32 mm.Width, male, 2.39 - 2.58 mm, female 2.88 mm. Biometric data are given in Table 1.
Frontal stria of head (Fig. 1 A) clearly impressed, feebly carinate and complete, the lateral portions convergent basally; the disk rather even, feebly depressed on apical half and sparsely clothed with fine punctures which are separated by about five times their diameter, with microscopic punctures densely intermingled. Labrum transverse, its anterior margin curved inwardly.
Pronotal sides (Fig. 1 B) nearly straight on basal half and weakly convergent apically from half to apical eighth, thence strongly arcuate and convergent to apices. Apical angles round. Marginal pronotal stria complete laterally and broadly interrupted behind head on anterior margin. Pronotal lateral stria complete and subcarinate laterally, the apical end strongly curved inwardly. Disk sparsely clothed with fine and somewhat deep punctures, and intermingled with other shallow microscopic punctures which are separated by three to five times their diameter. Antescutellar area with a deep impression.
Epipleural and elytral marginal striae complete and deeply carinate. Oblique humeral stria (Fig. 1 B) lightly impressed on basal third. First and 2nd dorsal striae complete, the basal portion of the 2nd bent inwardly. Third dorsal stria broadly interrupted on median third. Fourth, 5th dorsal and sutural striae absent. Disk of elytra with similar punctation as that of pronotum.
Propygidium (Fig. 1 C) irregularly covered with coarse, round and deep punctures which are unevenly separated by one-third to half their own diameter and become finer to outwards, and other microscopic punctures evenly intermingled. Surface of propygidium with a feeble depression on each medio-lateral area. Pygidium (Fig. 1 C) densely covered with coarse, round and deep punctures which are separated by about the diameter; a narrow band along postero-lateral margin clothed with microscopic punctures and strongly elevated.
Prosternal lobe (Fig. 1 D) broad and even, its anterior margin truncate; marginal stria clearly impressed and complete, its basal ends not convergent medially and deeply excavated; disk densely and microscopically punctate, the punctures being separated by three to five times their diameter. Prosternal keel flat and evenly clothed with fine punctures which are separated by about three times their diameter; carinal stria absent. Lateral and lateral marginal striae deeply impressed, carinate and complete.
Anterior margin of mesosternum (Fig. 1 D) strongly emarginate medially; marginal stria complete and deeply impressed; disk evenly and microscopically punctate, the punctures being separated by five to seven times their diameter. Meso-metasternal suture lightly impressed and feebly angulate at middle. Punctation of intercoxal disk of metasternum similar to that of mesosternum. Lateral metasternal stria deeply impressed, strongly carinate, obliquely and posteriorly extending, its apical end attaining near the metacoxa. Lateral disk densely covered with shallow, round and large punctures, which area absent on apical third.
Intercoxal disk of 1st abdominal sternum (Fig. 1 D) with similar punctation as that of metasternum; two lateral striae deeply impressed, the inner one entire and the outer present on apical two-thirds.
Protibia (Fig. 1 E, F) with four denticles on outer margin. Mesotibia with large three denticles, the apical denticle with two robust and short setae. Metatibia with large two denticles, the apical denticle with two robust and short setae.
Male genitalia as shown in Fig. 2 A-F; lateral sides of 8th sternum convergent posteriorly; the posterior apices of 8th sternum not extending inwardly; aedeagus slender, its sides nearly parallel.
Female genitalia as Fig. 2 G; spermatheca pear-shaped and sclerotized.
Specimens examined. Holotype, 1Åâ, ZIXXXX, Anatahan Is., northern Mariana Isls., 13-V-1992, S. Miyano leg. Paratypes, 1Åâ and 1ÅäZIXXXX, Anatahan Is., northern Mariana Isls., 11 and 12-V-1992, S. Miyano leg.
The holotype and the female of the paratype are deposited in the collection of the Natural History Museum and Institute, Chiba. The male of the paratype is preserved in the collection of the Institute of Entomology, Hokkaido University.
Remarks. In Desbordes's (1917) key to the species of the subgenus Platylister the new species traces to P. soronens Mars. from New Guinea, therefore it may be allied to P. soronens, but the new speices has the complete 2nd dorsal elytral stria. The elytral striation of this species is similar to that of P. abruptum Er., yet this new species is separated also from the latter species by the pronotal marginal stria which is interrupted behind head."