Tetramorium alternans

Identification
Csösz, Radchenko and Schulz (2007) - A member of the Tetramorium chefketi species complex in the Tetramorium caespitum species group.

Small Workers of T. alternans can be separated from related species by the lack of psammophore, relatively small eyes, very short scape without dorsal carina basally, less coarse body sculpture (i.e. dorsum of petiolar node is feebly ruguloso-reticulate and microreticulate), rounded petiolar node. Workers of T. alternans mostly resemble those of T. sanetrai, but petiole and frons characters give appropriate separation between them. To separate these species see Discriminant D(2b) function given under T. sanetrai.

Gynes of T. alternans can be recognised by the lack of psammophore, very short and smooth scape, wide scutum, relatively narrow petiole and postpetiole, and feebly reticulate petiole and postpetiole.

Distribution
Mediterranean coast of NW Africa.

Distribution based on Regional Taxon Lists
Palaearctic Region: Algeria, Morocco, Tunisia.

Nomenclature

 *  alternans. Tetramorium caespitum var. alternans Santschi, 1929e: 150 (w.) MOROCCO. Csösz, Radchenko & Schulz, 2007: 11 (q.m.). See also: Cagniant, 1997: 94. Raised to species: Güsten, Schulz & Sanetra, 2006: 17. Senior synonym of kahenae: Csösz, Radchenko & Schulz, 2007: 10.
 * kahenae. Tetramorium biskrensis var. kahenae Menozzi, 1934: 162 (w.q.) TUNISIA. [First available use of Tetramorium caespitum st. biskrensis var. kahenae Santschi, 1918c: 155; unavailable name.] Subspecies of biskrense: Menozzi, 1940: 270. Junior synonym of biskrense: Cagniant, 1997: 97; of alternans: Csösz, Radchenko & Schulz, 2007: 10.

Worker
Csösz, Radchenko and Schulz (2007) - Lectotype: CL: 700; CW: 685; FR: 275; FL: 275; SL: 485; ML: 770; MW: 440; PEW: 230; PEH: 255; NOH: 145; NOL: 140; PEL: 150; PPW: 265; PPL: 165; PPH: 210; SPL: 90; SPSP: 140; EL: 135; EH: 100; ED: 180.

Small to medium size, CS 733 [652, 820]. Whole body and appendages greyish black to black.Head nearly square CL/CW 1.01 [0.97, 1.05], with very feebly convex sides, straight, or slightly concave occipital margin and narrowly rounded occipital corners. Eyes small, EYE 0.168 [0.155, 0.176]. Frons moderately wide, FR/CS 0.39 [0.37, 0.41], frontal lobes as wide as frons, FL/FR 1.0 [1.0, 1.0]. Scape very short, SL/CS 0.71 [0.69, 0.74], without dorsal carina basally, surface feebly costulate. Promesonotal dorsum slightly convex, metanotal groove shallow, but distinct. Propodeal teeth moderately long, slightly curving upwards. Dorsal surface of petiole steeply rounded backward, NOH/NOL 1.03 [0.94, 1.13], petiole relatively high, PEH/NOL 1.84 [1.68, 2.04]. Whole body and appendages greyish black to black. General appearance coarsely rugose, ground surface microreticulate. Head dorsum longitudinally rugose and microreticulate, occiput and sides rugoso-reticulate and microreticulate. Alitrunk dorsum rugose or rugoso-reticulate and microreticulate. Mesopleuron usually coarsely microreticulate. Dorsum of petiolar node ruguloso-reticulate and microreticulate, medially microreticulate. Dorsum of postpetiole microreticulate. Polygonal striation continuous on 1st gastral tergite (see fig. 8.). Ventral surface of head with several short and few moderately long setae arising posteriorly to buccal cavity (see fig. 5.).

Queen
Csösz, Radchenko and Schulz (2007) - Small Small size, CS 999 [948, 1025]. Whole body and appendages greyish black. Head wider than long, CL/CW 0.92 [0.90, 0.95], with straight subparallel sides, straight occipital margin and narrowly rounded occipital corners. Frons moderately wide, FR/CS 0.41 [0.40, 0.42], frontal lobes as wide as frons, FL/FR 1.0 [1.0, 1.0]. Scape very short, SL/CS 0.69 [0.65, 0.71], without dorsal carina basally, moderately smooth and shiny. Head wider than scutum, MW/CS 0.94 [0.92, 0.97]. Propodeal teeth very short. Dorsal crest of petiolar node in frontal view straight. Petiolar node dorsum steeply rounded backward. Petiole and postpetiole relatively narrow, WAIST 0.93 [0.83, 1.0]. General appearance rugulose, ground surface smooth, more or less shiny. Head dorsum, occiput and sides ruguloso-reticulate, ground surface feebly microreticulate. Frons longitudinally rugulose and feebly microreticulate. Scutum and scutellum longitudinally rugulose, scutellum more or less smooth medially. Sides of alitrunk ruguloso-reticulate and feebly microreticulate, ventral part of katepisternum always smooth. Dorsum of petiolar node feebly reticulate and smooth, dorsum of postpetiole usually smooth. Polygonal striation disrupted on 1st gastral tergite, occasionally superficially striate basally. Ventral surface of head with several short and few longer setae, arising posteriorly to buccal cavity.

Male
Csösz, Radchenko and Schulz (2007) - Small Whole body and appendages black. Head with feebly convex sides, slightly rounded occipital margin and widely rounded occipital corners. Scutum wider than head. Propodeal teeth very short, propodeum angulate in profile. Dorsal crest of petiolar node with sharp transversal edge, slightly emarginated in frontal view. Head, alitrunk and waist finely sculptured, ground surface microreticulate. Head feebly reticulate ground surface microreticulate, dull. Scutum feebly rugulose, laterally and anteriorly smooth and shiny. Scutellum longitudinally rugulose, usually shiny medially. Sides of alitrunk, smooth and shiny. Dorsum of petiolar node finely reticulate and microreticulate, postpetiole smooth and shiny. Polygonal striation disrupted on 1st gastral tergite.

Type Material
Csösz, Radchenko and Schulz (2007) - Lectotype worker and Paralectotype workers (3 workers; ). Lectotype designation. We investigated three syntype workers mounted on one pin, labeled as: “Type” [red label] [:] “Rabat” [Morocco] “Otin” [:] 1.quinz. Aout 28 [in original description: 04.1928] [:] “T. caespitum alternans Sant.” SANTSCHI det. 19“29” [last two numbers are hardly readable] [:] Sammlung Dr. F. Santschi Kairouan. The lectotype is positioned on the distal end of the upper card (this is mentioned on the reverse side of lectotype label). The lectotype specimen is in very good condition.

References based on Global Ant Biodiversity Informatics

 * Borowiec L. 2014. Catalogue of ants of Europe, the Mediterranean Basin and adjacent regions (Hymenoptera: Formicidae). Genus (Wroclaw) 25(1-2): 1-340.
 * Cagniant H. 1997. Le genre Tetramorium au Maroc (Hymenoptera: Formicidae): clé et catalogue des espèces. Ann. Soc. Entomol. Fr. (N.S.) 33: 89-100.
 * Cagniant, H. "Liste actualisee des fourmis du Maroc (Hymenoptera: Formicidae)." Myrmecologische Nachrichten 8 (2006): 193-200.
 * Csősz S., A. Radchenko, and A. Schulz. 2007. Taxonomic revision of the Palaearctic Tetramorium chefketi species complex (Hymenoptera: Formicidae). Zootaxa 1405: 1-38.
 * Güsten, R., A. Schulz, and M. Sanetra. "Redescription of Tetramorium forte Forel, 1904 (Insecta: Hymenoptera: Formicidae), a western Mediterranean ant species." Zootaxa 1310 (2006): 1-35.
 * Menozzi C. 1934. Reperti mirmecofaunistici raccolti dal Prof. L di Caporiacco nelle oasi di Cufra e in altre localita del deserto Libico. Atti della Societa dei Naturalisti e Matematici di Modena (6)13(65): 153-166
 * Poldi B., M. Mei, and F. Rigato. 1995. Hymenoptera, Formicidae. Vol 102. Checklist delle specie della fauna Italiana: 1-10.