Myrmecosticta exceptionalis Maruyama, sp. nov.

(Figs. 10–25)

Holotype, 3 “ MALAYSIA: Sarawak, Lambir Hills National Park, 18 X 2004, Matsumoto T. / ATTM 590 / HOLO- TYPE Myrmecosticta exceptionalis Maruyama ” (no. 590). Paratypes: 1, same data as holotype but 17 V 2004 (no. 399); 2, ditto, 16 V 2004 (no. 418); 1, ditto, 8 XI 2004 (no. 501); 2, ditto, 8 XI 2004 (no. 502); 6, ditto, 7 XI 2004 (no. 541); 5, ditto, 13 X 2004 (no. 572); 17, ditto, 12 X 2004 (no. 575); 22, ditto, 18 X 2004 (no. 590). See, Table 1 for detailed collecting data.

Symbiotic host. Morphotype S of the Aenictus laeviceps .

Distribution. Malaysia (Borneo).

Etymology. The Latin exceptionalis means exceptional, for the exceptionally myrmecoid body shape within the tribe Aleocharini . The body shapes of other Aleocharini members are of the standard staphylinid-type, similar to most other species of Aleocharinae, and no myrmecoid forms have been described previously.

Description. Body surface smooth, shining. Almost uniformly reddish brown except for mouthparts and tarsi somewhat paler. Head (Figs. 12–14) oval, much longer than wide in dorsal view, widest at eyes, with a v-shaped prominence between antennal insertions in dorsal view; clypeus with a small projection medially; surface sparsely covered with setae; eyes large, about half as long as head. Antennae short, evidently shorter than combined length of head and pronotum; segment I slender, gently widened apically; segment II small, conical; segment III short, slightly longer than II; segments IV–X slightly longer than wide; segment XI parallel-sided around base, rounded at apex. Pronotum (Fig. 15) much longer than wide (length/width=1.43–1.50), strongly convex; surface sparsely and finely punctate, with 4 macrosetae along midline and 1 macroseta antero-laterally. Elytra slightly widened posteriorly, wider than long; surface with dense but fine microsculpture, and moderately covered with short setae, without macrosetae. Metaventrite (Fig. 16) shining, with 2 large setae at middle and 3–4 small setae around posterior area. Abdomen (Figs. 17–18) with segments III–VIII sparsely covered with setae; number of macrosetae from tergites III–X: 2, 2, 2, 3, 4, 7, 3, 3; with tergite VIII posterior margin rounded; sternite VIII with 10–12 macrosetae. Male: median lobe of aedeagus (Fig. 24) with flagellum coiled 7.5 times; apical lobe of paramere elongate and slightly curved. Female: spermatheca (Fig. 25) with basal part constricted, apical half parallel-sided; apical part somewhat oval.

Measurements. BL, ≈ 3.1–3.4; FBL, ≈ 1.7–1.9; HW, 0.57–0.61; EL, 0.313–0.337; AL, 1.49–1.69; PL, 0.66– 0.75; PW, 0.44–0.53; ELW, 0.66–0.78; HTL, 1.31–1.35. N=5.

Diagnosis. This species can easily be distinguished from any members of the tribe Aleocharini by the myrmecoid body shape. This species can be distinguished from the other myrmecoid species of Aleocharinae by characters which define the tribe Aleocharini, e.g., presence of a pseudosegment on the apex of the labial palpus.