Vombisidris jacobsoni ( Forel, 1915 ), 2011

Sorger, D. M., 2011, Redescription and history of Vombisidris jacobsoni (Forel, 1915) (Hymenoptera, Formicidae), Revue suisse de Zoologie 118 (1), pp. 149-155 : 151-154

Vombisidris jacobsoni ( Forel, 1915) Figs 1-5

TYPE MATERIAL: 1 lectotype worker (upper specimen), 1 paralectotype worker (lower specimen) labelled “Type”, “ Atopula \ Jacobsoni \ Â Type For.”, “27\ No 15\ Sinabang\ (Simalur\ Sumatra\ I 1913 \ (E. Jacobson)” [= leg. Edw. Jacobson], “sp. A. Jacobsoni For.”, “ Vombisidris \ jacobsoni \ ( FOREL)\[on backside:] Det: 1995\ A. Francoeur”, “ LECTOTYPE \ Atopula jacobsoni \ FOREL, 1915 \ des. D.M. Sorger 2010”, “ PARALECTOTYPE \ Atopula jacobsoni \ FOREL, 1915 \ D.M. Sorger 2010”, “ Vombisidris \ jacobsoni (Forel) \ det. D.M. Sorger 2010”, specimens glued on two squared card boards on the same pin, in coll. Forel at MHNG (Muséum d’Histoire Naturelle, Genève), Switzerland. – 1 paralectoype worker labelled “Cotypus”, “ Atopula \ Jacobsoni \ Â Type For.\ Simalur”, “ SYNTYPUS \ Atopula \ Jacobsoni\ A. Forel, 1915 ”, “ MUSEO GENOVA \ coll. C. Emery\ dono 1925”, “ PARALECTOTYPE \ Atopula jacobsoni \

FIG 1

Vombisidris jacobsoni , lectotype worker from Sumatra, Simalur, in the Forel Collection of the Muséum d’Histoire Naturelle , Genève. Habitus , dorsal view. © www.antbase.net, published with permission .

FOREL, 1915 \ D.M. Sorger 2010”, “ Vombisidris \ jacobsoni (Forel) \ det. D.M. Sorger 2010”, glued on a squared card board, in coll. Emery at Museo Civico di Storia Naturale “Giacomo Doria”, Genova, Italy.

TYPE LOCALITY: Indonesia, Sumatra, Simalur Island (alternative spelling: Simeulue), Sinabang (capital city) (2° 29′ 0″ N, 96° 22′ 30″ E, Google Earth)

DESCRIPTION OF WORKER: A species of the genus Vombisidris as defined by Bolton (1991), with the following characters.

Colour of entire body light brown to yellow (two type specimens almost entirely light brown, one type specimen almost entirely yellow). Femora and tibiae lighter than rest of body (whitish yellow except for infuscated bases) (figs 1, 2, 3).

Entire body with short thick, blunt (abruptly truncated apically) setae (some setae on postpetiole even slightly clavate); distinctly shorter setae on head (fig. 3), longer and finer setae on scapes (fig. 4). In addition, some fine, short scattered appressed hairs on gaster.

Head, dorsum of mesosoma, petiole and postpetiole with distinct rugoreticulum. Spaces between costulae mostly smooth and shiny. Pronotum angulate, cervical shield with a few longitudinal ridges overlaying granulate microsculpture (figs 1, 2). Sides of mesosoma with some rugae overlaying microsculpture (fig. 3). Dorsum of petiolar peduncle with very finely reticulate sculpture. Gaster slightly depressed in lateral aspect, smooth and shiny, some short striae at base of tergite 1 (figs 1, 2, 3).

FIGS 2-5

Vombisidris jacobsoni , paralectotype worker from Sumatra, Simalur in the Forel Collection of the Muséum d’Histoire Naturelle , Genève. (2) Habitus , dorsal view. (3) Habitus , lateral view. (4) Head , full face view. (5) Labels of lectotype and paralectoype workers (on one pin). © www.antbase.net, published with permission.

Head slightly longer than wide, sides behind eyes feebly convergent (fig. 4). Eyes protruding and relatively large (EI 24, 25) containing 8-10 ommatidia in longest row. Clypeus strongly convex in lateral aspect (fig. 3), in full face view its anterior margin covered by its convexity (fig. 4). Subocular groove complete, from mandibular insertion backwards to latero-occipital margin. Mandibles smooth with some fine short hairs, hair pits indistinct (fig. 4). Dorsal and lateral faces of mesosoma forming an angle, mesosoma broadest at outer pronotal angles, continuously becoming narrower towards propodeum in dorsal aspect (maximum pronotum width ca. twice maximum propodeum width), sides feebly concave (figs 1, 2), dorsum evenly convex in lateral aspect, metanotal groove absent (fig. 3). Propodeum in dorsal aspect slender (figs 1, 2); spiracle situated below level of spines (fig. 3). Propodeal spines long, slightly downcurved in lateral aspect (fig. 3), curved inwards in dorsal aspect (figs 1, 2). Petiole (figs 1, 2, 3) with long peduncle bearing a pair of teeth in front of spiracle; anterior and dorsal face of node separated by a transverse ridge forming a blunt angle in lateral aspect, ventrally with anterolateral small teeth. Postpetiole in dorsal aspect (figs 1, 2) subtrapezoidal, widest anteriorly. Legs relatively short (FL <HW), femora and tibiae conspicuously thickened (figs 1, 2, 3).

MEASUREMENTS: Lectotype worker (coll. Forel): TL 3.8; HL 0.86; HW 0.81; CI 95; EL 0.20; EI 25; SL 0.60; SI 74; PW 0.59; AL 1.20; FL 0.79; FI 97; paralectotype worker 1 (coll. Forel): TL 2.8; HL 0.81; HW 0.73; CI 90; EL 0.17; EI 24; SL 0.54; SI 75; PW 0.51; AL 1.09; FL 0.70; FI 96; paralectotype worker 2 (coll. Emery): TL 3.7; HL 0.83; HW 0.80; CI 97; EL 0.20; EI 25; SL 0.60; SI 75; PW 0.60; AL 1.10; FL 0.79; FI 98.

NOTES: In Bolton’s (1991) key V. jacobsoni reaches couplet 3 where a short metafemur contradicts the absence of a metanotal groove. Following Bolton’s (1991: 5) species-group descriptions, V. jacobsoni belongs to the V. australis group: “ V. australis -group. Subocular groove complete. Legs and antennae relatively short. Metanotal groove vestigial to absent. A convenience-group to hold species not fitting any of the above groups [Other species groups in Vombisidris are: V. bilongrudi -group, V. philax -group and V. dryas -group, see Bolton (1991).]. Includes australis, harpeza, occidua.”.

Vombisidris australis ( Wheeler, 1934) differs from V. jacobsoni in size (small- er), presence of mesonotal suture (although indistinct) and shape and length of propodeal spines (shorter, blunt); V. harpeza Bolton, 1991 differs from it in head shape (sides behind eyes approximately parallel) and presence of metanotal groove (although almost obliterated); and V. occidua Bolton, 1991 differs in size (larger), occurrence of basigastral costulae (vestigial) and colour (head and mesosoma dark brown, gaster lighter brown, legs yellow) (see Wheeler, 1934; Bolton, 1991).

In Forel’s (1915: 27) original description of V. jacobsoni , he mentions the smallest specimen to be paler than the rest and wonders about its maturity. Even though, it is impossible to know whether I have seen all specimens Forel based his original description on (since he does not mention the total number of specimens studied), I believe the aforementioned specimen to be the one I examined and photographed as the paralectoype in the Forel Collection (figs 2-4). Total Length of specimen deviates from Forel’s original description – probably due to differences between my measurement technique and that of Forel.