Stenamma koreanense

Lyu et al. (2002) reported the following details regarding the type collection. The nest was located about 5 m away from an intermittent stream. It was under a rock (approximate diameter 30 cm, with 15-20 cm buried in the soil). The ant nest side of the stream was somewhat shallow and without flowing water at that time. The nest area was exposed (sunny and not well shaded during most of the day). It was shaded in early morning and late afternoon due to high mountains at both sides of the stream. The majority of the nest structure ran parallel to the stream with chambers for gyne and brood located near the center of the nest. One queen and 31 workers were collected.

Identification
Lyu et al. (2002) - This species belongs to the Stenamma owstoni species group as defined by DuBois (1998: 287- 288).

Stenamma koreanensis is most likely to be confused With Stenamma ussuriense. Specimens of the latter species have been collected m approximately similar habitats (Primorskiy Kray, Kedrovaya Pad Preserve and Suputinka [32 - 35 km SE Ussuriysk); we know of no collections of Stenamma from the intervening areas (mostly adjacent areas of the Korean peninsula) other than Collingwood (1976) whose specimens we were unable to examine. While it is possible Stenamma koreanensis represents the extreme edge of variation of S. ussuriense it is more likely this is a closely related species. The petiole is longer and more pedunculate in S. ussuriense than in S. koreanensis. In all specimens examined, the apical two teeth (ultimate and penultimate teeth) of the mandible are less pronounced (not as long) as in S. koreanensis (Fig. 8; see caste section below). The metanotal impression is deeper in S. ussuriense and the thoracic dorsum sculpture is much more longitudinally carnate in this species than in S. koreanensis. Finally, S. koreanensis has transverse carinae between the propodeal spines (Fig. 6; see caste section below) while S. ussuriense lacks these (or they are very faint).

It is possible that this species may also be confused with Stenamma kurilense. The latter species is presently known from only two workers. Comparisons were not made directly with specimens (as they were with the remaining species in this section). However, notes of the second author and the related publication (DuBois 1998) were used to compare this species with S. koreanensis. Although the length of the propodeal spines and ratio of length of propodeal spines to propodeal plates is similar for both species, the mandible of known specimens of S. kurilense always contain 7 teeth. The propodeal spiracle of S. koreanensis is not enlarged (and is more typical of the genus) than what is found in S. kurilense. Specimens of S. koreanensis have a more rugose thoracic dorsum; the propodeal dorsum and area between the propodeal spines have several transverse carinae. Although the base of the first gastral tergite is carinate, the carinae extend only 1/5 to 1/4 the length of the postpetiole (compared to nearly 1/2 the length of the postpetiole in S. kurilense). Although the mesopleuron in S. koreanensis is punctate (somewhat like that found in S. ussuriense and S. kurilense), it approaches rugose in overall sculpture (Fig. 3; see caste section below).

It is also possible that S. koreanensis may be confused with Stenamma nipponense. However, the compound eyes are smaller than in S. koreanensis. The length of the propodeal spines is significantly longer in S. nipponense and the petiole is more pedunculate (with a proportionally longer stalk in S. nipponense). Additionally, the carinae on the base of the first gastral tergite are longer in S. nipponense and the sculpture is more scabrous on the thoracic dorsum. The metanotal impression is deeper and the mesopleuron is more rugose (with little evidence of punctures in S. nipponense).

It is also remotely possible that S. koreanensis may be confused with Stenamma owstoni. However, specimens of the latter species are typically larger with larger compound eyes. As with S. nipponense, the petiole is more pedunculate with a longer stalk in S. owstoni than S. koreanensis. Similarly, the thoracic dorsum is more scabrous in S. owstoni. Although the length of the carinae on the first gastral tergite are similar in size, the apical two mandibular teeth are less pronounced in S. owstoni.

Distribution based on Regional Taxon Lists
Palaearctic Region: Republic of Korea.

Nomenclature

 *  koreanense. Stenamma koreanensis Lyu, DuBois & Cho, 2002: 512, figs. 1-8 (w.q.) KOREA.

Worker
(n = 31) TL 4.50 (4.36-4.69); HL 1.01 (0.98-1.05); HW 0.88 (0.85-0.90); CI 97.21 (84.34-90.00)%; SL 0.75 (0.73-0. 78); SI 85.09 (80.56-88.57)%; AL 1.28 (1.23-1.35); PRW 0.61 (0.60-0.63); PL 0.46 (0.43-0.48); PH 0.27 (0.25-0.28).

Holotype. TL 4.45, HL 1.00, HW 0 .88, CI 87.5%, SL 0.78, SI 88.57%, AL 1.25, PRW 0.63, PL 0.45, PH 0.28.

Mandible with 7-8 teeth (apical two prominent), gap after second apical tooth before denticles start (gap approximately same size as tooth). Anterior clypeal margin in full face view with median lobe weakly emarginate; apex in lateral view convex, then flat (near mandible). Compound eye with 12 ommatidia in greatest diameter. Scape not reaching occiput by amount less than first funicular segment. Propodeal spines of moderate length, approximately 1/3 length of declivitous face of propodeum (shorter in some specimens). Metanotal impression very shallow, depth approximately 1/3 the length of propodeal spines; wide, approximately 4X as wide as deep, depth decreasing towards anterior. A large pit is present at the posterior ventral edge of the pronotum and is lined with microsetae. A similar pi tis present between the bases of the meso- and meta-coxae; it is not lined with microsetae. Propodeal plates approximately the same length as (or slightly shorter than) propodeal spines, directed posteriorly. Anterior subpetiolar process convex and slightly reduced. Petiole pedunculate: stalk approximately 1/2 the length of petiole, node rising gradually. Anterior subpost-petiolar process typical for Stenamma workers, posterior subpostpetiolar process reduced. Head rugose (most similar to the sculpture of Stenamma ussuriense and Stenamma debile) except as follows: frontal area smooth with small carinulae (especially near clypeal emargination), carinulae diverging towards posterior; central 1/ 3 of frontal area (between antennal sockets) glassy-smooth; venter of head rugose: occipital area rugose. Interstices glassy-smooth throughout with scattered small piligerous punctures. Thoracic dorsum rugose; rugae with slight longitudinal orientation. Thoracic pleura rugose. Neck of pronotum punctulate. Metanotal impression weakly scrobiculate with surrounding sculpture blending into sculpture of impression. Mesopleuron with weakly scrobiculate median area. Procoxae transversely carinate, meso- and meta-coxae longitudinally cannate to smooth; femora with faint longitudinal carinae: remainder of legs glassy-smooth with scattered piligerous punctures. Propodeal dorsum with rugose, glassy-smooth declivitous face. Petiolar node dorsum rugose: remaining surfaces heavily punctulate. Postpetiolar node dorsum rugose: remaining surfaces heavily punctulate. First gastral tergite base carinate with numerous carinae diverging towards posterior; majority of carinae 1/4 to 1/5 length of postpetiole. First gastral sternite base glassy-smooth with almost no trace of carinae. Remainder of gaster glassy-smooth, with scattered piligerous punctures. Setae on head erect to appressed. Setae on clypeus erect, setae on mandible decumbent to appressed. Setae on scape and funiculus appressed. Setae on alitrunk erect to suberect, setae on legs mostly decumbent to appressed with a few suberect setae on coxae. Setae on anterior surface of petiolar node appressed, setae on dorsum, posterior surface and side decumbent to suberect. Setae of venter of petiole absent. Setae on postpetiole erect to decumbent on all surfaces, becoming more decumbent on anterior surface of node. Setae on gaster suberect to decumbent. Color predominantly brown with alitrunk dark brown and appendages yellowish brown, Tip of gaster also yellowish brown, Compound eyes black. Setae yellow.

Queen
TL 5.18; HL 1.03; HW 0.95; CI 92.19%; SL 0.79; SI 83.05%; AL 1.59; PRW 0.74; PL 0.53; PH 0.31.

As described for the worker except for usual morphological changes associated with flight and reproduction except as follows. Mandible with 7 teeth (mandibular teeth worn extensively in this specimen). Compound eye with 14 ommatidia in greatest diameter; 3 ocelli present in typical appearance for members of this genus. Thoracic modifications for flight musculature obscure metanotal impression. Wings absent from this specimen, but scars indicate wings were present earlier. Propodeal plates slightly shorter than propodeal spines. Thoracic dorsum rugose, rugae with decided longitudinal orientation. Thoracic pleura rugose with a longitudinal orientation. Propodeal dorsum with transversely carinate basal face and glassy smooth declivitous face. Lateral surfaces of petiolar and postpetiolar nodes with faint longitudinal rugae (in addition to heavily punctulate surfaces). First gastral tergite base with majority of carinae extending between 1/4 and 1/3 length of postpetiole.

Type Material
Holotype and 30 paratype workers, 1 gyne. KOREA: Mt. Odae, Kangwon, 18 V 1995, Dong-Pyeo Lyu. This is approximately 128 degrees 35' E by 37 degrees 45' N. The elevation of the collection locality is approximately 500 m. Specimens distributed as follows: ChungbukNational University, Cheongju, South Korea (CBNU), holotype worker and 20 paratype workers; 2 paratype workers;  2 para type workers;  2 paratype workers; MBDPC 3 paratype workers, 1 gyne. Holotype specimens bears a red, partly handwritten label: Stenamma koreanensis Holotype. Paratype workers and gyne bear white, printed labels: Stenamma koreanensis Paratype.

Etymology
This species is named in honor of the peninsula where it was first collected (Korea).

References based on Global Ant Biodiversity Informatics

 * Guénard B., and R. R. Dunn. 2012. A checklist of the ants of China. Zootaxa 3558: 1-77.
 * Lyu D.P., M.B. DuBois, S. Cho. 2002. Stenamma koreanensis, sp. n. from the Korean Peninsula (Hymenoptera: Formicidae: Myrmicinae). Sociobiology 40: 511-523.
 * Lyu D.P., S. Cho. 2004. Review of the genus Stenamma (Hymenoptera: Formicidae) in Korea. Journal of Asia-Pacific Entomology 7: 263-267.