Syllophopsis sechellensis

In Japan this species is found in open habitats and nests under stones, in the bark of trees, or in plant cavities (Japanese Ant Image Database). In Madagascar, Heterick (2006) found that sifted litter is the most effective collection method for individual workers of S. sechellense, though one small nest series was taken from a rotten log. The species is found in dry tropical forest and gallery forest habitats in Antsiranana, Mahajanga and Toliara Provinces.

Identification
Heterick (2006) - The designation of the lectotype fixes the name of this widespread taxon, whose populations vary chiefly in the degree of cephalic punctation. Its sculptured mesopleuron immediately enables the Monomorium sechellense worker to be distinguished from the worker of Syllophopsis cryptobia and Syllophopsis modesta. Queens are larger, darker and more heavily sculptured than those of S. cryptobium.

Distribution
Outside of Madagascar, this species has a wide distribution in the Indo-Pacific region (e.g., Bolton 1987; Wetterer 2002) and probably also occurs in Australia (Heterick 2001).

Deyrup (2016, p. 423) reported S. subcoeca from Dominica, writing ‘specimens were found by digging in an open, dry, scrub area’. These specimens from Dominica (Cabrits National Park; 2 May 2006; M. Deyrup), however, were misidentified; they are actually Syllophopsis sechellensis (M. Deyrup, pers. comm.), the first record of S. sechellensis from Dominica. (Wetterer & Sharaf, 2021)

Distribution based on Regional Taxon Lists
Afrotropical Region: Comoros, Saint Helena. Australasian Region: Australia. Indo-Australian Region: Borneo, Fiji, Guam, Indonesia, Malaysia, Micronesia (Federated States of), New Guinea, Northern Mariana Islands, Samoa, Singapore, Tonga. Malagasy Region: Seychelles. Neotropical Region: Barbados, Grenada. Oriental Region: Cambodia, Myanmar, Thailand, Vietnam. Palaearctic Region: Japan.

Nomenclature

 * . Monomorium fossulatum subsp. sechellense Emery, 1894a: 69, fig. (w.q.) SEYCHELLES IS (Marie-Anne I.).
 * Type-material: lectotype worker (by designation of Heterick, 2006: 179), 1 paralectotype worker.
 * [Note: original description also mentions a syntype queen.]
 * Type-locality: Seychelles: Marie-Anne I., iii.-v.1892 (Ch. Alluaud).
 * Type-depository: MSNG.
 * [Misspelled as seychellensis by Forel, 1907d: 93, Chapman & Capco, 1951: 165, and others.]
 * Combination in Syllophopsis: Ward, et al. 2015: 73.
 * Subspecies of fossulatum: Emery, 1900c: 326; Forel, 1907d: 93; Forel, 1912k: 163; Wheeler, W.M. 1922a: 1027; Emery, 1922e: 172; Wheeler, W.M. 1934h: 12; Wheeler, W.M. 1935g: 23; Chapman & Capco, 1951: 165; Ettershank, 1966: 92.
 * Synonym of fossulatum: Wilson & Taylor, 1967: 64; Dorow, 1996a: 78.
 * [Note: Wilson & Taylor, 1967, and Dorow, 1996a, give fossulatum as senior synonym, but sechellensis has priority (Bolton, 1995b: 266).]
 * Status as species: Bolton, 1995b: 266; Wetterer, 2002: 129; Imai, et al. 2003: 133; Wetterer & Vargo, 2003: 417; Jaitrong & Nabhitabhata, 2005: 28; Heterick, 2006: 179 (redescription); Clouse, 2007b: 249; Terayama, 2009: 153; Pfeiffer, et al. 2011: 47; Sarnat & Economo, 2012: 89; Wetterer, et al. 2016: 19.
 * Senior synonym of fossulatum: Bolton, 1995b: 266; Imai, et al. 2003: 133; Terayama, 2009: 153.
 * Distribution: Antigua, Barbados, Fiji Is, Hawaii Is, Japan, Madagascar, Micronesia, Myanmar, Samoa, Seychelles, Taiwan, Thailand, Tonga.
 * Current subspecies: nominal plus papuasiae.
 * fossulatum. Monomorium fossulatum Emery, 1895k: 465 (w.q.) MYANMAR.
 * Type-material: 1 syntype worker, syntype queens (number not stated, “some”).
 * Type-locality: Myanmar (“Burma”): Rangoon (L. Fea).
 * Type-depository: MSNG.
 * Status as species: Forel, 1903a: 687; Bingham, 1903: 205; Forel, 1912a: 55; Wheeler, W.M. 1922a: 1027; Emery, 1922e: 172; Wheeler, W.M. 1929g: 60; Teranishi, 1940: 57; Chapman & Capco, 1951: 165; Ettershank, 1966: 89; Wilson & Taylor, 1967: 65; Onoyama, 1980: 198; Ogata, 1991b: 107; Morisita, et al. 1992: 39; Dlussky, 1994: 54; Dorow, 1996a: 78; Lin & Wu, 2003: 66 (error).
 * Synonym of sechellensis: Wilson & Taylor, 1967: 64; Dorow, 1996a: 78.
 * [Note: Wilson & Taylor, 1967, and Dorow, 1996a, give fossulatum as senior synonym, but sechellensis has priority (Bolton, 1995b: 266).]
 * Junior synonym of sechellensis: Bolton, 1995b: 266; Imai, et al. 2003: 133; Terayama, 2009: 153.

Worker
Heterick (2006) - Lectotype: HML 1.12 HL 0.41 HW 0.34 CeI 83 SL 0.31 SI 91 PW 0.23. Non-types: HML 1.07–1.24 HL 0.40–0.45 HW 0.33–0.36 CeI 78–84 SL 0.31–0.35 SI 94–100 PW 0.22–0.25 (n=20).

HEAD: Head rectangular; vertex planar or weakly concave; frons shining and smooth except for piliferous pits; pilosity of frons a mixture of incurved, semi-erect setae and slightly shorter decumbent setae. Eye minute, eyes consisting of one or two ommatidia only; (in full-face view) eyes set at about midpoint of head capsule; (viewed in profile) eyes set posteriad of midline of head capsule. Antennal segments 12; antennal club three-segmented. Clypeal carinae always weakly defined; anteromedian clypeal margin straight between strongly divergent clypeal carinae, clypeus descending almost vertically to horizontal arc of mandibles and sometimes transversely carinate below level of antennal insertions; paraclypeal setae moderately long and fine, curved; posteromedian clypeal margin extending slightly beyond level of posterior margin of antennal fossae. Anterior tentorial pits situated nearer mandibular insertions than antennal fossae. Frontal lobes sinuate, divergent posteriad. Psammophore absent. Palp formula 2,2. Mandibular teeth four; mandibles linear-triangular and smooth (except for piliferous pits); masticatory margin of mandibles strongly oblique; basal tooth approximately same size as t3 (four teeth present).

MESOSOMA: Promesonotum shining and smooth on dorsum, lower mesopleuron strongly punctate; (viewed in profile) anterior promesonotum smoothly rounded, thereafter more-or-less flattened, promesonotum on same plane as propodeum; promesonotal setae greater than twelve; standing promesonotal setae a mixture of well-spaced, distinctly longer, erect and semi-erect setae which are curved distally and often paired, interspersed with much shorter, incurved, decumbent setae; appressed promesonotal setulae few, mainly on sides of promesonotum. Metanotal groove strongly impressed, with distinct transverse costulae. Propodeum shining, dorsum and sides of propodeum mainly smooth, with weak to strong striolae on declivitous face, metapleuron also with weak to strong striolae; propodeal dorsum flat throughout most of its length; propodeum distinctly angulate, propodeal angles produced as short denticles; length ratio of propodeal dorsum to its declivity about 1:1; standing propodeal setae consisting of one prominent pair anteriad, with a few to many erect to decumbent setae on/around dorsal and declivitous faces of propodeum; appressed propodeal setulae very sparse or absent; propodeal spiracle equidistant from metanotal groove and declivitous face of propodeum. Vestibule of propodeal spiracle absent or not visible. Propodeal lobes present as vestigial flanges or small strips of cuticle only.

PETIOLE AND POSTPETIOLE: Petiolar spiracle lateral and situated slightly anteriad of petiolar node; node (viewed in profile) conical, vertex rounded; appearance of node shining and smooth throughout; ratio of greatest node breadth (viewed from front) to greatest node width (viewed in profile) about 4:3; anteroventral petiolar process absent or vestigial; ventral petiolar lobe absent; height ratio of petiole to postpetiole between 4:3 and 1:1; height–length ratio of postpetiole between 4:3 and 1:1; postpetiole shining and smooth; postpetiolar sternite without anterior lip or carina, or this structure vestigial.

GASTER: Pilosity of first gastral tergite consisting of a mixture of incurved, semi-erect setae and slightly shorter decumbent setae.

GENERAL CHARACTERS: Color pale, depigmented yellow. Worker caste monomorphic.

Queen
Heterick (2006) - HML 1.68–1.78 HL 0.48–0.51 HW 0.45–0.46 CeI 90–96 SL 0.42–0.43 SI 91–93 PW 0.41–0.43 (n=9).

HEAD: Head square; vertex weakly concave or planar; frons shining and finely longitudinally striolate and microreticulate; pilosity of frons a mixture of incurved, semierect setae and slightly shorter decumbent setae. Eye elliptical, curvature of inner eye margin may be more pronounced than that of its outer margin; (in full-face view) eyes set at about midpoint of head capsule; (viewed in profile) eyes set posteriad of midline of head capsule.

MESOSOMA: Mesoscutum broadly convex anteriad, convexity reduced posteriad; pronotum, especially, also mesoscutum and mesopleuron shining with scattered punctation, otherwise smooth; length–width ratio of mesoscutum and scutellum combined between 2:1 and 3:2; axillae separated by width of at least one axilla; standing pronotal/mesoscutal setae a mixture of well-spaced, distinctly longer, erect and semi-erect setae which are curved distally, interspersed with much shorter, incurved, decumbent setae; appressed pronotal, mescoscutal and mesopleural setulae very sparse or absent; propodeum shining, uniformly weakly striolate; propodeum distinctly angulate, propodeal angle sharp; propodeal dorsum sloping posteriad, and depressed between raised propodeal angles; standing propodeal setae consisting of up to a dozen or more longer erect and shorter sub-erect setae; appressed propodeal setulae very sparse or absent; propodeal spiracle nearer metanotal groove than declivitous face of propodeum; propodeal lobes present as well-developed, rounded flanges.

WING: Wing not seen (queens dealated).

PETIOLE AND POSTPETIOLE: Petiolar spiracle lateral and situated well anteriad of petiolar node; node (viewed in profile) cuneate, vertex tapered; appearance of node shining and microreticulate; ratio of greatest node breadth (viewed from front) to greatest node width (viewed in profile) about 4:3; anteroventral petiolar process absent or vestigial; height ratio of petiole to postpetiole about 1:1; height–length ratio of postpetiole about 4:3; postpetiole shining and microreticulate; postpetiolar sternite depressed at about its center, with anterior process developed as a short, conspicuous spur angled at 45–90.

GASTER: Pilosity of first gastral tergite consisting of a mixture of incurved, erect and semi-erect setae and slightly shorter decumbent setae.

GENERAL CHARACTERS: Color brown. Brachypterous alates not seen. Ergatoid or worker-female intercastes not seen.

Type Material
Heterick (2006) - Lectotype: worker, Seychelles, Marianne, C. Alluaud, 1892. Paralectotype: worker, same data as above (MCSN). (Carded specimen removed from same pin as lectotype above and repinned, together with new labels.)

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