Lordomyrma azumai Santschi

Lordomyrma azumai (Santschi)

(Figs 1–8)

Rogeria (Rogeria) azumai Santschi, 1941: 3, fig. 3, worker; Minoo, Osaka, JAPAN = Lordomyrma nobilis Yasumatsu, 1950: 75, fig. 2, worker, male; Mt Hikosan, Kyushu, JAPAN (Synonymy: Brown, 1952: 124).

Lordomyrma azumai (Santschi), Brown, 1952: 124.

When describing the junior synonym L. nobilis, Yasumatsu (1950) perceptively recognised the congeneric relationship between this species and L. furcifera.

Distribution: The only Lordomyrma species known from JAPAN: Eastern Honshu (Chiba, Ibaraki and Tochi prefectures), Southern Honshu (south from Hyogo and Mie prefectures), Shikoku and Kyushu. A distribution map, with English-language keys and a synopsis of characters distinguishing L. azumai from other Japanese ants, is given by Imai et al (2003), complimenting the parallel, expanded Japanese edition of the same work in the Gakken Super Visual Encyclopedia series, and the Compact Disc and website versions issued by the Japanese Image Database Group.

L. azumai is considered “rather rare” (Imai et al, 2003). Masuko & Kannari (1980) reported biological observations, mainly from Mt. Kiyosumi, Chiba Prefecture, and noted details from previous Japanese-language papers by authors including Azuma and Yasumatsu. The ants were found patchily distributed in moist soil horizons with fresh to well-decomposed organic content under natural broadleaf forest. Nests were located under a stone, in a crack in a stone, in a damp twig or a fallen nut. Four reported colonies collected during February were monogynous, larvae were present in good numbers, pupae were not reported. Alate gynes and males were present in mid-February nests, and a possible colony-founding dealate gyne was taken alone in leaf-litter in late March. Worker nest compliments ranged up to 86. When disturbed workers feign death by rolling-up their bodies and enclosing their antennae within the antennal scrobes.

. Material examined: JAPAN: HONSHU - CHIBA: Mt Kigosumi, 3 workers (K. Masuko, 18 Feb 1978). GIFU: 9km E of Gero, worker (I. Löbl, 31.7.1980, 450- 550m.). - WAKAYAMA: Kitayama-kyoo, Tado (K. Azuma, 31.v. 1951, 400m). HYOGO: Aiyima near Kobe (M. Azuma, 27. iv. 47; worker with labels reading “ paratype ” and “ Rogeria (Rogeria) azumai Santschi 1941)(MCZC). KYUSHU - FUKUOKA: Hikosan (Buzen) worker with red MCZC paratype label, no 28740, and blue handwritten paratype label in nobilis = azumai unit tray (K. Yasumatsu, 6. viii 1940)(MCZC). - KAGOSHIMA: Oosumi Peninsula, “Oonogara-dake” mountain trail, Mt Takakuma, 31o 30’N, 130 o 49’E, samples from 3 colony series (K. Eguchi, 9. viii. 2007: Eg 09viii07-04 (3612 ft); Eg 09viii07-06 (rotting wood fragment, 3612 ft); Eg 09viii07-11 (3320 ft). - NAGASAKI: Hirado I, Mt Yasumari, 5 workers, male (H. Sakai, 10 Aug 1981, nest under stone). All ANIC unless indicated otherwise, donated by the collectors.

Worker: General features, conformation and color as illustrated. Antennal funiculus clavate but without delineation of a distinct segmentally defined club; the 3 apical segments progressively longer than those preceding them. Palpal formula maxillary 4: labial 3 (2 specimens dissected). When viewed from behind (perpendicular to the vertex) the top of the head rounds evenly on each side to join the sides. Promesonotum only slightly elevated in lateral view (APE relatively acute: ca. 25 o). Pronotal shoulders with small humeral nodules at either side of the raised section behind the nucal collar, otherwise broadly rounded. Metanotal groove distinct in lateral view, lacking a clearly incised suture, slightly depressed below propodeal summit, rising steeply to pronotal dorsum which is barely domed in profile. Petiole triangular in lateral-view with a short, weak transverse dorsal crest. Mandibles somewhat irregularly longitudinally striate. Clypeus smooth, shining. Frons and occiput longitudinally striaterugose, the striae more-or-less reticulate at the sides, more straight medially, interstices filled with polished fine puncturation. Sides of head below and behind eyes rugose. Head ventrally smooth and shining. Microsculpture of antennal foveae minutely punctate-rugose, without directional orientation (much like the interstitial microsculpture of frons). Scapes and femora subopaque, densely minutely punctate. Anterior coxae microsculptured much like antennal foveae. Occipital collar finely granulose-reticulate. Dorsum and sides of mesosoma generally rugose like sides of head; propodeum less coarsely rugose, with transverse trend on dorsum, several short ribs spanning metanotal groove, a few transverse striae between bases of propodeal spines and on propodeal declivity. Petiole and postpetiole more finely rugose than sides of propodeum. Gaster dorsally and ventrally moderately shining, with arrayed minute point-punctures. These may be generally distributed, but in some specimens they are largely concentrated in rings or somewhat stellate clusters around the bases of the hairs of the moderately dense pilosity, and in more-or-less clearly defined narrow diagonal lines crossing at the hair-bases. In maximum expression this arrangement is seen under high magnification as an indistinct cross-hatch of narrow punctate lines enclosing shining diamond-shaped sections of smoother cuticle, with a hair-base and a cluster of surrounding punctae at each intersection. That pattern is more-or-less vestigial in some specimens. The smooth areas generally reflect vestiges of micropuncturation. Pilosity dense, as illustrated, the hairs curved, tapering, flexuous, whitish in color. Color generally medium reddish-brown, the gaster usually slightly darker than elsewhere, legs slightly lighter. Dimensions: TL 4.2 4.7 HW 0.79, 0.82; HL 0.82, 0.87; CI 96, 94; EL 0.14, 0.14; OI 18, 17; SL 0.62, 0.66; SI 78, 80; PW 0.61, 0.64; WL 1.17, -; DPW 0.21, 0.24; DPpW 0.26, 0.31; GW 1.08, 1.00.

Gyne: Generally as illustrated. Basically similar to worker except for the presence of ocelli, relatively large eyes and the usual mesosomal and gastral attributes distinguishing gynes. The above characterization of worker sculpturation and pilosity applies. Ventral propodeal spine as in worker. Palpal formula not known. Wing venation unavailable here. Dimensions: TL 4.9; HW 0.89; HL 0.92; CI 97; EL 0.18; OI 20; SL 0.62; SI 69; PW 0.70; SW 0.70; WL 1.32; DPW 0.27; DPpW 0.36; GW 1.19. Described from 2 dealate worker-associated specimens (1 measured): Takakuma Mts, Kagoshima (K. Eguchi accs Eg 09viii07-04, Eg 09viii07-11) (ANIC).

Diagnosis: Characterized by its simple general conformation, with relatively basic, unelaborated sculpturation and pilosity. I consider L. azumai to be the most structurally conservative known Asian Lordomyrma species - the taxon perhaps least divergent from the stock ancestral to all Lordomyrma species. This view is supported by the fact that the geographically peripheral Lordomyrma faunas of Australia and Fiji include species of similar conformation (Taylor, 2009).