Strumigenys mutica

A rare species, S. mutica is found at forest margins extending to more open situations, nesting in soil or decaying wood (Japanese Ant Image Database). Brown (1949) reported that it was collected from a "nest under a stone in the clay soil of a somewhat dry place."

Identification
Bolton (2000) - A member of the Strumigenys mutica-group. Differentiation of the three species Strumigenys media, mutica and Strumigenys yaleogyna depends primarily on the distribution of specialised hairs on the head and body. Wilson & Brown (1956) point out that this may not be enough to define the species accurately in this group, but for the present it remains the best method to confirm identity.

The diagnostic pilosity consists of erect to suberect stout remiform hairs on the head, alitrunk, waist segments and first gastral tergite, distributed as follows.

S. mutica: one or two pairs on head close to occipital margin, one pair on mesonotum, one pair on petiole, one or two pairs on postpetiole, at least one pair on basal half of first gastral tergite.

S. yaleogyna: one pair on head close to occipital margin, one pair on mesonotum, absent from petiole, postpetiole and base of first gastral tergite.

Strumigenys media: absent from all these locations.

Apart from pilosity characters the petiole node in dorsal view is broader than long in mutica, at least as broad as long in the other two and usually distinctly longer than broad in media. The postpetiole disc is almost or quite as densely reticulate-punctate as the petiole in mutica and media. It is much less densely sculptured in yaleogyna, where the disc may appear mostly smooth and shining.

Despite these features I remain dubious about the distinctivness of these species. The solution to the problem lies in the aquisition of much more material and a more detailed analysis than can be achieved here and now.

For the separation of Strumigenys takasago from these three, see under that name.

Bharti & Akbar (2013) - Member of the widely distributed mutica group which previously constituted the genus Kyidris now abandoned (Baroni Urbani & de Andrade, 1994; Bolton, 1999). The distinctive form of the mandibles (only apical half of each mandible with teeth while basal halves are edentate, forming a large gap between the mandibles) coupled with the compact biconvex mesosoma, propodeum usually unarmed and spongiform appendages of waist segments reduced. S. mutica with one or two pairs of specialized hairs on head close to occipital margin, one pair on mesonotum, one pair on petiole, one or two pairs on postpetiole and at least one pair on basal half of first gastral tergite differentiates it from closely related species S. yaleogyna and S. media which are lacking such distribution of hairs on head and body (Bolton, 2000).

Distribution based on Regional Taxon Lists
Indo-Australian Region: Borneo, Indonesia, Malaysia, Singapore. Oriental Region: India, Taiwan. Palaearctic Region: China, Japan, Republic of Korea.

Nomenclature

 *  mutica. Kyidris mutica Brown, 1949d: 3, fig. 1 (w.) JAPAN. Wilson & Brown, 1956: 442 (q.m.); Imai, Kubota, et al. 1985: 47 (k.). Combination in Pyramica: Bolton, 1999: 1672; in Strumigenys: Baroni Urbani & De Andrade, 2007: 124. Senior synonym of itoi: Brown & Yasumatsu, 1951: 94; of nuda: Brown, 1952c: 124. See also: Bolton, 2000: 455.
 * nuda. Kyidris nuda Brown, 1949d: 23 (q.) TAIWAN. Junior synonym of mutica: Brown, 1952c: 124.
 * itoi. Polyhomoa itoi Azuma, 1950: 36, figs. (w.) JAPAN. Junior synonym of mutica: Brown & Yasumatsu, 1951: 94.

Type Material
Holotype worker and five paratype workers described below taken on Shikoku at "Hirooka (Tosa)" by H. Okamoto. These specimens were sent me by Dr. Yasumatsu; the holotype and paratypes will be returned to him at Kyushu University, Fukuoka, Kyushu, Japan. One each paratypes will be deposited in the Museum of Comparative Zoology and the U.S. National Museum.

Bolton (2000) - Holotype worker and paratype workers, JAPAN: Shikoku, Hirooka (Tosa) (H. Okamoto) (KU,, ) [examined].

Worker
Holotype. TL 2.05 mm., HL 0.51 mm., WL 0.52 mm., CI 79, MI 22.

Head as described for genus; convex dorsally in both directions across the occipital region, anterior to this straight dorsally in lateral profile view but weakly convex from side to side as seen from above. Just about the whole of the nearly straight convergent ventrolateral cephalic borders are visible when viewed from a position directly dorsal to the head. Eyes small, consisting of about 15 facets each; oval, moderately convex, situated astride the ill-defined lower borders of the scrobes and clearly visible from above. Scrobe broad and rather deep, occupying nearly the entire side of the head, partially divided anteriorly by a short longitudinal carina. Clypeus about as broad as long, with a rounded posterior angle separating it from the poorly-defined and slightly depressed frontal area. Free clypeal border evenly rounded, with a slight tendency toward an indistinct blunt pointing of the middle anteriorly. The clypeal disc is weakly convex from side to side and noticeably sloping anteriorly, so that the anterior portion of the free border is on a level slightly ventral to that of the middle dorsum of the closed mandibles.

When opened, the mandible is seen to be bent near its base and to possess a diagonal basal border which terminates distally in a prominent rounded lamella of thin, translucent chitin which is approximately as broad as the diastema following it distally. Rounded diastema followed in turn by a series of rather even (basalmost slightly larger), small acute teeth. which are fused one to the next except for the extreme tips to form a sort of cross-striate lamella, denticulate along the inner edge. There are eleven of these little teeth or denticles, followed by an apical tooth on the downcurved apices of each mandible, the latter larger and broader, slightly set off from the rest and not fused with the next to last tooth basally. After the basal convexity, the external mandibular border is very weakly concave most of its length. Seen from the side, the mandibles are fairly convex dorsally. As in Smithistruma, the shafts are considerably hollowed ventrally, and medially so that they form longish convex-concave shells, seen when a mandible is mounted in balsam, but not easily determined when in place on the insect. Antennal scape (L 0.30 mm.) very feebly S-shaped, depressed and gradually and slightly incrassate, widest near the middle. Funiculus (L 0.48 mm.) with segment V slightly longer than I-IV taken together; I and IV nearly equal in length and each slightly longer than II and III taken together; III broader than long and distinctly shorter than II.

Promesonotum subglobose seen from above, promesonotal suture obliterated or nearly so; anterior pronotal margin :md humeral angles not developed, rather evenly rounded. Propodeum shorter than promesonotum and seen from above a little less than half as wide and longitudinally oblong. From the side, the two major regions of the alitrunk are separately convex and meeting at a well-defined postmesonotal sutural depression (much like that of Serrastruma spp.) which also forms a definite constriction when viewed from above. Propodeum with a broadly rounded angle in profile, without teeth or lamellae developed, but instead with the merest trace of a low vertical carina (on each side of the declivity) which bears a row of small, narrowly spatulate curved hairs. The declivity itself is weakly concave from side to side.

Petiole with a peduncle as long as or slightly longer than the node, the latter in side view with a steeply sloping anterior face and the summit rather narrowly rounded. Seen from above, the petiolar node is semicircular, with a narrow lamellate or spongiform band bordering the posterodorsal margin, other petiolar spongiform appendages obsolete. Petiolar node about .6 the width of the postpetiolar node, the latter small, transversely elliptical, with a convex dorsum, about half the greatest width of the gaster. Postpetiole with only moderately well-developed spongiform appendages. and these restricted more or less to the posterior and ventral surfaces.

Gaster of the usual dacetine sort; basal dorsal costulae rather few but distinct and long, blending with a poorly-defined superficially reticulate-striate area between and behind them, the whole roughened area extending over the anterior half or so of the first tergite; remainder of gastric dorsum smooth and shining.

Head, alitrunk, nodes and appendages densely reticulate-punctulate and opaque, except for the bottoms of the punctulae, many of which are smooth. causing the surface to appear very weakly shining in certain lights.

Head, including clypeus, with fairly abundant small appressed and subreclinate linear-spatulate hairs, the same on the scapes, directed apically, and more sparsely on the dorsum of the alitrunk, directed toward the midline. Slightly longer subappressed and appressed spatulate and subclavate hairs directed posteriorly on the nodes and posteriorly directed short appressed pointed hairs on the gastric dorsum. Legs with abundant, very small appressed and subappressed clavate and spatulatehairs. In addition to the ground pilosity, there exist larger paired erect clavate hairs, one pair on the occiput. another on the posterior promesonotal dorsum, one pair on each of the nodes, and about five pairs on the gastric dorsum. Apex of gaster and ventral surface with some shorter, more slender hairs.

Color light ferruginous yellow.

Paratype. TL 2.00-2.15 mm., HL 0.50-0.54 mm., WL 0.53-0.56 mm., CI 76-80, MI 21-24.

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