Strumigenys lewisi

The hunting behaviour of S. lewisi was investigated by Masuko (1984). See Hunting Tactics in Short-Mandibulate Strumigenys for more about this ant's hunting behavior.

Identification
Bolton (2000) - A member of the godeffroyi complex in the Strumigenys godeffroyi-group. See notes under Strumigenys godeffroyi.

Yoshimura and Onoyama (2007) - Strumigenys lewisi and Strumigenys kumadori are very similar to Strumigenys geminata. S. lewisi and S. kumadori can be separated from the latter by having a more feeble propodeal spine and the lateral surface of pronotum completely reticulate-punctate or at most with a small smooth patch above the fore coxa.

Strumigenys kumadori is distinguished from S. lewisi by the following characters: 1) in the workers, all of two paired hairs on the apicoscrobe and anterior portion of the mesonotum are long and distinctly flagellate in the former, but both of the hairs are plumose-filiform or filiform in the latter (Figs 12,13 – see figures in caste section below and in the caste section for Strumigenys kumadori), 2) the eyes of the queens are relatively large in the former, but relatively small in the latter (Fig. 56), 3) the lateral ocelli of queens are distinctly large (Figs 20, 55) with pigmented outer margins in the former, but relatively small (Figs 26, 55) or vestigial and not distinctly bordered with pigment around them in the latter, 4) the mesoscutum of queen in dorsal view is wide (MsWI>63) and weakly constricted at posterior 1/3, and lateral corners by the constriction are not angular in the former, but narrow (MsWI<63) and strongly constricted, and the lateral corners are angular in the latter, 5) the transverse furrow on mesoscutum of queen is curved posteriorly in the former (Fig. 19), but nearly straight in the latter (Fig. 25), 6) fore wings of queen are relatively broad in the former (Fig. 41), but are reduced and narrow in the latter (Fig. 43), 7) the radial vein on the hind wing does not reach the costal margin in the former (Figs 41, 42), but does so in the latter (Figs 43, 44), 8) the mandible of male is relatively narrow in the former (Figs 30, 32), but is relatively wide in the latter (Figs 36, 38), 9) on the male genitalia in lateral view, volsella is gently curved and the corner is not broadened in the former (Fig. 46), but is abruptly curved and the corner is distinctly broadened in the latter (Fig. 50).

In the present study, the characters in the queen have most distinctly separated between the two species, S. kumadori and S. lewisi. The eyes, ocelli, mesonotum, and wings are useful characters to distinguish these two species. While much developed, the male's mesosoma did not provide useful characters to separate the two species, while the queen's one did. The reduced male mandible, however, provided useful distinguishing characters.

Distribution
Bolton (2000) - Bingham (1903) recorded this species from Burma but the record has not been confirmed in this survey and is probably incorrect; the specimens, now lost, may perhaps have been Strumigenys peraucta, a newly described Indian species of this complex. W. M. Wheeler (1935) and Wilson & Taylor (1967) record lewisi from Hawaii, where it is an introduction, and Arakelian & Dlussky (1991) record it on Kunashir Island in the Kuril'skiye Ostrova, which is almost certainly part of its normal range.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Niue, Philippines. Oriental Region: Myanmar, Sri Lanka, Taiwan, Vietnam. Palaearctic Region: China, Democratic Peoples Republic of Korea, Japan, Malta, Republic of Korea.

Biology
Yoshimura and Onoyama (2007) - Our collection data of the colonies suggest that polygyny is common in S. lewisi and Masuko et al. (1985) reported S. lewisi is predominantly polygynous.

Latitudinal variations of S. lewisi: Two morphological indices, DlOI and MsHI, showed negative tendencies with latitudinal gradient. The relationship between DlOI and latitude (r=-0.614, n=34, P<0.0001) was significant, although that between MsHI and latitude was not significant (r=-0.314, n=34, P=0.071). Reduction of the mesoscutum, ocelli, and wings suggest that the ability to fly is degenerated. The degeneration in the queens gives us two hypotheses for S. lewisi; 1) a range of the dispersion in northern population is smaller than that in southern population, 2) the northern population has dispersed their genes relying on the flying ability of the males.

The distribution areas and sites of S. kumadori and S. lewisi. overlap in Honshu, Kyushu, and Korea (JADG, 2003a, 2003b, 2003c; Terayama, 1999). We additionally confirm the presence of both species in Taiwan. Nest habitats of the two species are the same or very similar (Masuko et al., 1985), and we actually confirmed that both species were collected from a single leaf litter sample taken from a quadrat of 0.5m x 0.5m. Therefore, these two have completely sympatric distribution.

Nomenclature

 *  lewisi. Strumigenys lewisi Cameron, 1886: 229 (w.q.) JAPAN. Wheeler, G.C. & Wheeler, J. 1955a: 140 (l.). Subspecies of godeffroyi: Mayr, 1887: 569 (footnote); Wheeler, W.M. 1906c: 318; Emery, 1924d: 321; Wheeler, W.M. 1923b: 4; Wheeler, W.M. 1928d: 115. Revived status as species: Bingham, 1903: 149; Brown, 1949d: 16. See also: Bolton, 2000: 794; Yoshimura & Onoyama, 2007: 671.

Worker
Bolton (2000) - TL 2.6-2.7, HL 0.65-0.70, HW 0.45-0.48, CI 68-71, ML 0.30-0.32, MI 45-47, SL 0.38-0.42, SI 83-89, PW 0.28-0.30, AL 0.70-0.73 (10 measured).

Characters of godeffroyi complex. Cephalic dorsum with pair of erect hairs closest to midline on occipital margin short stiff and erect, straight to shallowly evenly curved but the apical half not abruptly curved anteriorly nor looped. With head in full-face view the dorsolateral margin posterior to the flagellate apicoscrobal hair has a row of 3-4 stiffly projecting hairs. These hairs contrast with the marginal hairs anterior to the flagellate hair as they are more cylindrical (i.e. not spatulate), more elevated and less strongly curved anteriorly. Ground-pilosity on pronotal dorsum sparse and dilute, not appearing as a pelt. Dorsum and side of pronotum evenly finely reticulate-punctate everywhere or with a small smooth patch on the side above the fore coxa. Dorsum of pronotum with a pair of erect hairs in addition to the humeral pair. In most samples this pair of hairs is flagellate but in some the hairs are looped apically and in some they appear filiform, though these may represent breakage. Pair of erect hairs on mesonotum usually flagellate but again in some individuals they may be looped or appear filiform. Pleurae and side of propodeum mostly to entirely smooth, any reticulate-punctate sculpture present is confined to periphery. Propodeal declivity with a broad and very conspicuous lamella, the propodeal teeth at most only weakly expressed (may be vestigial or indistinguishable from the lamella), entirely confluent with the lamella. Disc of postpetiole unsculptured. Basigastral costulae conspicuous but not extending half the length of the tergite.

Yoshimura and Onoyama (2007) - HL 0.65 - 0.71, HW 0.48 - 0.50 CI 69.8 - 76.0, ML 0.31 - 0.35, MI 46.9 - 50.0, SL 0.37 - 0.40, SI 76.4 - 82.0, DSA 3 L 0.12 - 0.13, DSA 3 W 0.19 - 0.20, DSA 3 I 140.0 - 155.6 (6 measured).

Ventrolateral margin of head at level of eye not extended outward. Antenna consisting of 6 segments. Fully closed mandible in full-face view curvilinear. On the mandible, a distinct, long and spiniform preapical tooth present close to apical teeth. Apical teeth consisting of two distinct spiniform teeth and three small intercalary teeth between them: basal of the two spiniform teeth longer than the apical one: basal one of the three intercalary teeth distinctly smaller than apical two. With mesosoma in lateral view, the diameter of the excavated area of mesopleural gland moderate, much less than the maximum width of the first coxa. Mesosoma except for propodeal declivity without spongiform tissue. Propodeal declivity equipped with a broad and conspicuous lamella; propodeal tooth very feeble and not sclerotized; posterior margin of the lamella convex, and immediately under the propodeal tooth of the margin sometimes slightly concave. Ventral margin of petiole in lateral view with longitudinal spongiform tissue. With petiole in lateral view, anteriormost point of lateral spongiform lobe nearly reaching level of anterior face of node.

Dorsal and lateral surfaces of pronotum entirely reticulate-punctate, sometimes with a small patch above the fore coxa. Metapleuron and side of propodeum entirely smooth. Limbus distinct. Abdominal tergite IV longitudinally sculptured at the basal portion, but not entirely covered.

With head in full-face view, a pair of long, curved distally plumose filiform hairs, rarely not serrate, present on apicoscrobe; hairs posterior to the apicoscrobal hairs with shorter barbs, laterally projecting filiform hairs; anterior to the apicoscrobal hairs without laterally projecting hair. With head in lateral view, dorsal surface from level of eye to preoccipital margin with erect to reclinate ground-pilosity; hair on vertex margin distinctly differentiated from that on level of eye; from highest point of vertex to preoccipital margin with the anteriorly directed ground-pilosity, which is very feebly curved basally so that each hair is elevated and inclined upward away from the cephalic outline. A pair of hairs present on the pronotal humeri and mesonotum; those on the humeri usually flagellate; those on the mesonotum usually short filiform hairs but sometimes long curved. Dorsum of hind femur without short erect hairs, but with two or three (usually two) long erect flagellate hairs. Dorsal surface of hind basitarsus with one freely projecting flagellate hair. The whole of the dorsal surface of abdominal tergite IV with flagellate hairs. Basal portion of abdominal sternite IV covered with matted hair-like tissue.

Body almost unicolorous, reddish brown to yellowish brown.

Queen
Yoshimura and Onoyama (2007) - HL 0.63 - 0.70, HW 0.45 - 0.52 CI 71.5 - 80.0, ML 0.29 - 0.33, MI 44.8 - 49.2, SL 0.33 - 0.38, SI 67.9 - 76.2, DlO 0 - 0.02, DlOI 0 - 4.94, EL 0.08 - 0.11, EI 16.6 - 21.6, HD 0.30 - 0.32, PrH 0.18 - 0.22, MsW 0.26 - 0.31, MsWI 50.4 - 60.6, MsH 0.07 - 0.13, MsHI 14.2 - 27.0, DSA 3 L 0.12 - 0.15, DSA 3 W 0.19 - 0.24, DSA 3 I 146.9 - 188.7 (10 measured).

Generally similar to the worker with the usual caste differences. Head thinner than that of queen of Strumigenys kumadori in lateral view. With head in full-face view, the ocelli weakly developed situated at posterior 1 / 4 of the head with brown pigment around them, but ocelli often vestigial and visible only with the pigments. Eye relatively small. A distinct, long spiniform preapical tooth present close to apical teeth. Apical teeth consisting of two spiniform teeth and three, rarely two, small intercalary teeth: basal one of the two spiniform teeth longer than another apical one: basal one of the three (or two) intercalary teeth distinctly smaller than the apical two (or the apical one). With mesosoma in lateral view, the highest point of the mesoscutum situated anterior to extension line of the mesopleural wing process in most cases; mesopleural gland orifice distinct but its maximum width not reaching maximum width of the procoxa; the pits on the mesepisternum invisible. Metanotum in lateral view slightly convex posteriorly. Propodeal spine developed and weakly sclerotized, and under which the lobe of spongiform tissue distinctly developed. With the spongiform tissue on propodeal declivity in lateral view, its posterior margin weakly concave under the propodeal spine. With mesoscutum in dorsal view, its anterior margin relatively sharp, both lateral margins strongly constricted at posterior 1 / 3, lateral corners by the constriction strongly angular. Transverse furrow on the mesoscutum nearly straight. Mesoscutum narrow (MsWI less than 63), its width not reaching 3 / 4 of the head width in frontal view. With petiole in lateral view, the lobe of spongiform tissue strongly developed.

Both of the fore and hind wings distinctly reduced in width at distal 1 / 2. Only costal (C) and radial (R 1) veins and r-rs cross vein clearly present on fore wing. Vestiges of the radial sector (Rs), M + Cu, and cubital (Cu) veins sometimes visible as pigmented lines but not sclerotized. On the hind wing, radial (R) vein present, reaching to costal margin and extended distally; jugal lobe absent.

Head, pronotum, mesonotum, and metanotum entirely reticulate-punctate. Central part of mesepisternum and most part of propodeum ventral to propodeal spiracle not punctate and smooth. Dorsal margin of petiole reticulate-punctate. Dorsal surface of postpetiole not punctate and smooth. Limbus present on abdominal tergite IV. Abdominal tergite IV longitudinally sculptured at the basal portion, but sculptures not extended to posterior half of the tergite.

Hairs on the pronotal humeri long and flagellate. Mesonotal dorsum with erect, straight or flagellate hairs. Dorsum of hind femur without short erect hairs, but with 2 or 3 (usually 2) long erect flagellate hairs. Dorsal surface of abdominal tergite IV with long filiform hairs. Hair-like tissue on the basal portion of abdominal sternite IV developed. Fore and hind wings densely hairy.

Body almost unicolorous, reddish brown to yellowish brown

Male
Yoshimura and Onoyama (2007) - HL 0.44 - 0.46, HW 0.43 - 0.46, CI 95.9 - 101.3, SL 0.09 - 0.11, SI 20.8 - 23.0, DlO 0.05 - 0.06, EL 0.18 - 0.19, HD 0.36 - 0.37, PrH 0.21 - 0.22, MsW 0.40, MsWI 91.5 - 94.0, MsH 0.16 - 0.17, MsHI 35.1 - 38.7 (3 measured).

With head in full-face view, portion of posterior to the eyes subglobose; anterior to the eyes distinctly narrowed anteriorly. Ocelli distinct; the median ocellus situated about posterior 1 / 4 of the head length, the lateral ocelli not reaching to the posterior border of the head. Eyes distinctly developed and prominent, occupying central 1 / 3 of lateral margin of the head in full-face view. Eye in lateral view broadened ventrally, and its outer margin expanded anteroventrally and flattened posteriorly. Anterior tentorial pits unclear. Anterior margin of the clypeus in full-face view slightly convex, but nearly straight. Frontal carinae undeveloped and antennal insertions exposed. Antennae long and filiform, consisting 13 segments. Scape short and broad. Pedicel short and broadened apically. With mandible in full-face view, its apical portion gradually curved and narrowed; the basal lamella distinctly recognized and strongly projected; apical to the lamella edentate. Mandible in lateral view subtriangular, but broader than that of Strumigenys kumadori. With labrum in full-face view; its apical portion distinctly extended laterally; the distal lobes entirely reduced, and apical margin of the labrum concave toward the midpoint. Palp formula 1, 1 (1 observed on SEM). Mesosoma in lateral view shorter and higher than that of the queen. Mesoscutum distinctly developed and strongly raised dorsally in lateral view. Mesoscutellum developed and slightly extended posteriorly. With the mesonotum in dorsal view, the median notal suture weakly impressed but mostly invisible; the notauli weakly impressed; the parapsidal furrows impressed and continued to the distinct transscutal suture; anterior margin of the scuto-scutellar suture distinctly sculptured longitudinally, but weak on the lateral portion, so that the division of the axillae often indistinct. Metanotum in lateral view slightly extended posteriorly. With the propodeum in lateral view, a distinct spiracle situated at the midheight; the posterior margin with distinct corner, but the spine or dent reduced; the lamella absent ventral to the propodeal corner, even if its ventral portion with a carina along the propodeal declivity. With the petiole in lateral view, the node more gently raised than that of worker and queen; the lateral spongiform lobe entirely reduced; the longitudinal spongiform tissue feebly present. Ventral margin of abdominal sternite III without a distinct process except for its extreme anterior part. Abdominal segment IV in lateral view thicker than that of worker and queen, the ventral expansion more gentle.

With genitalia in ventral view, the basal ring broader than long; lateral margins of the parameral plate weakly concave; the cuspis of volsella distinctly shorter than the digitus. With genitalia in lateral view, an anteriorly directing process, such as the barb, present at apical 1 / 4 of its ventral margin; the digitus of volsella abruptly curved ventrally and broadened at the corner.

Only costal (C) and radial (R 1) veins and r-rs cross vain clearly present on fore wing. Vestiges of the radial sector (Rs), M + Cu, and cubital (Cu) veins sometimes visible as pigmented lines but not sclerotized. On the hind wing, radial (R) vein present, reaching costal margin and extended distally; jugal lobe absent.

Head, pronotum, mesonotum, and metanotum entirely reticulate-punctate. Central part of mesepisternum and most part of propodeum ventral to propodeal spiracle not punctate and smooth. Dorsal margin of petiole reticulate-punctate. Dorsal surface of postpetiole not punctate and smooth. Limbus absent.

Two pairs of standing filiform hairs present on vertex. With head in lateral view, long and frontally projecting hairs absent anterior to median ocellus. Mesonotum with long, erect, and filiform to flagellar hairs present. Dorsal surface of the petiole, abdominal tergite III and IV with sparse filiform hairs.

Body almost unicolorous, blackish brown to reddish brown, legs same or lighter.

Type Material
Syntype workers and queen, JAPAN: Nagasaki, 3.iii. (G. Lewis) [examined].