Lasius productus

This species nests in rotting wood and stumps, or dead portions of tree trunks in broad-leaved deciduous forests. The nuptial flights take place in August and September (Japanese Ant Image Database).

Identification
A Japanese species closely related to Lasius emarginatus. All three castes possess extraordinarily long appendages. This character readily separates L. productus from L. emarginatus, and from all other Lasius across the Holarctic.

Distribution
Seifert (2020) - Occurrence data from the Japanese islands of Tsushima, Kyushu, Shikoku and Honshu contains three altitudinal records that range from 50 to 1000 m.

Distribution based on Regional Taxon Lists
Palaearctic Region: China, Japan.

Nomenclature

 *  productus. Lasius (Lasius) productus Wilson, 1955a: 95 (w.q.m.) JAPAN. See also: Yamauchi, 1979: 156; Seifert, 1992b: 46.

Worker
Within the HW range 0.86-1.12 mm., the SI is between 112 and 124 (see Fig. 5), and the ML exceeds the EW by about 1.3 X.

Size averaging larger than in other members of the subgenus; PW 0.59-0.73 mm., mean 0.686 mm., based on 15 workers from 6 nest series. Anterior border of median clypeal lobe broadly rounded as in other niger complex members. Dentition very constant, with three perfectly formed basal teeth in every specimen examined. Propodeum elevated relative to thorax as in Lasius emarginatus. Scapes densely covered with predominantly decumbent hairs; standing hairs very scarce or absent. Tibiae with sparser hairs which are mostly appressed. Color varying from concolorous medium brown as in Lasius niger (e.g. paratypes from Hikosan VIII-6-1940 and Sobosan IX-8-1933) to bicolorous with contrasting reddish brown alitrunk and dark brown gaster and head (e.g. paratypes from Hikosan XI-21-1939). The holotype nest series falls about intermediate between these two extremes; the holotype can best be described as having a medium reddish brown alitrunk barely contrasting with the gaster. None of the material examined reaches the extreme bicolorous condition of the typical European emarginatus; moreover, in Lasius productus the head is usually noticeably lighter than the gaster.

Seifert (2020) - Large (CS 1050 µm). Head and scape length indices outstandingly large (CL/CW900 1.139, SL/CS900 1.169). Postocular distance rather small and eye rather large (PoOc/CL900 0.235, EYE/CS900 0.248). Torulo-clypeal distance large (dClAn900 5.65). Terminal segment of maxillary palp outstandingly long (MP6/CS900 0.293). Pubescence on clypeus moderately dense (sqPDCL900 4.35); frontal pubescence of medium length (PLF900 28.8). Scape densely covered with decumbent pubescence hairs. Gular setae rather long, only slightly shorter than pronotal setae (GuHL/CS900 0.117, PnHL/CS900 0.134); setae numbers rather low (nOcc900 9.8, nGen900 3.2, nGu900 3.1, nSc900 10.2, nHT900 6.7, nSt900 1.9). Coloration: varying from concolorous medium brown to bicolored with contrasting reddish brown mesosoma and dark brown head and gaster.

See table 11 in Seifert 2020 for additional morphometrics. The abbreviated names of various quantitative data shown above are defined here: Seifert 2020 Lasius characters.

Queen
ML in three queens examined ranging 0.32-0.34 mm., exceeding all other members of the genus.

Characterized by its higher SI and tendency toward larger size. Following are measurements for three queens identified in the course of the present study. Japan, no further data (H. Sauter leg.; MCZ), HW 1.88 mm., SL 1.58 mm., SI 84, ML 0.32 mm.; Hikosan, Kyushu, IX-18-1939 (K. Yasumatsu leg. and Coll.), HW 1.79 mm., SL 1.55 mm., SI 87, ML 0.32 mm.; Hirooka, Shikoku VIII-29-1935 (H. Okamoto leg. and Coll.), HW 1.82 mm., SL 1.52 mm., SI 84, ML 0.34 mm.

Male
SI of the one specimen measured was 105, greatly exceeding all other members of the genus.

In the single specimen examined (Sobosan, Kyushu, IX-10-1933; Yasumatsu leg. and CoIL), HW 0.98 mm., SL 1.03 mm., SI 105. Subgenital plate very similar to that typifying emarginatus. Scapes densely covered with rather short, predominantly subdecumbent hairs. Tibiae with sparse, appressed to decumbent hairs.

Type Material
HOLOTYPE. A worker from Mt. Imano (Imanoyama), Shikoku (H. Okamoto leg. and ColI.). PW 0.72 mm., HW 1.04 mm., HL 1.17 mm., SL 1.23 mm., SI 119, ML 0.30 mm., EW 0.22 mm. Paranidotypes in the Yasumatsu ColI.,, , and Holgersen Coll.

References based on Global Ant Biodiversity Informatics

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