Odontomachus procerus Emery, 1893

Satria, Rijal, Kurushima, Hiroaki, Herwina, Henny, Yamane, Seiki & Eguchi, Katsuyuki, 2015, The trap-jaw ant genus Odontomachus Latreille (Hymenoptera: Formicidae) from Sumatra, with a new species description, Zootaxa 4048 (1), pp. 1-36 : 16-21

Odontomachus procerus Emery, 1893 stat. nov.

( Figs. 1 , 8 , 9 , 10 , 17, 18)

Odontomachus latidens subsp. procerus Emery, 1893: 203 , queen, type locality: West Malaysia. Chapman & Capco, 1951: 45. Synonymy under Odontomachus latidens by Brown, 1976: 104. Stat. nov.

Odontomachus latidens subsp. sumatranus Emery, 1900: 671, fig. 4, worker, queen, type locality: Indonesia (Sumatra). Synonymy under Odontomachus latidens by Brown, 1976: 104. Syn. nov.

Type materials and images examined. “ Odontomachus latidens subsp. procerus ”: holotype (queen in MCSN), Peninsular Malaysia: Perak [mesosoma of the holotype heavily deformed by pinning]; “ O. latidens subsp. sumatranus ”: syntypes (9 workers, 2 queens in MCSN; 2 workers in NHMW), Indonesia: North Sumatra: Si- Rambe (XII.9 D-III.91, E. Modigliani leg.) [mesosoma of the syntype queens partly deformed by pinning].

Images of the type material of the following species provided in AntWeb v5.17.5 (http://www.antweb.org) were also examined: “ O. latidens subsp. procerus ”, queen (CASENT0903998); “ O. latidens subsp. sumatranus ”, worker (CASENT0903999).

Non-type materials examined. Indonesia: West Sumatra: Mt. Sago, 50 Kota District (ca. 1000 m alt.), 06.IX.2012, S. Rijal leg., SAGO-01-02, 31 workers ( SKYC, RSC); Alahan Panjang, 4.I.1992, F. Ito leg., FI92-252, 2 workers ( SKYC, RSC). Malaysia: Sabah: Sayap Kinabalu, ca. 1000 m alt, 13.VII.1996, Sk. Yamane leg., 2 workers ( SKYC, RSC); same loc., 13.VII.1996, K. Eguchi leg., 1 worker ( SKYC, RSC); Poring, Kinabalu (550– 600 m alt), 17.III.1995, Sk. Yamane leg., 1 worker ( SKYC, RSC); Muaya, 27–28.VIII.2012, K. Matsunaga leg., 12 workers ( SKYC, RSC); same loc., 19.X.2012, K. Matsunaga leg., 1 worker ( SKYC, RSC). Sarawak: Bt. Entimau (610 m alt), 23.IV.1994, Mahmud leg, 1 worker ( SKYC, RSC).

Materials used for DNA barcoding. Colony SAGO-01-12 (individual no. RJ20150126-3, accession no. LC056052 ).

Worker measurements and indices. Syntypes (n=9): HW 2.69–2.93 mm, HL 3.55–4.00 mm, SL 3.65–4.00 mm, IFLW 0.68–0.75 mm, EL 0.36–0.40 mm, MDL 2.12–2.33 mm, WL 4.40–4.70 mm, PTL 0.59–0.73 mm, PTH 1.35–1.60 mm, CI 72–81, SI 133–148, MDI 56–62, PTHI 206–228.

Non-types (n=10): HW 2.66–3.13 mm, HL 3.65–4.40 mm, SL 3.80–4.10 mm, FLW 0.69–0.81 mm, EL 0.41– 0.47 mm, MDL 1.97–2.49 mm, WL 4.15–4.90 mm, PTL 0.63–0.76 mm, PTH 1.45–1.82 mm, CI 71–77, SI 126– 144, MDI 52–63, PTHI 203–252.

Worker description. Relatively large (HL 3.55–4.40 mm, WL 4.15–4.90 mm). Head in full-face view slightly longer than broad, with posterior margin almost straight; median furrow on vertex present as a dark line; each side of line hardly swollen; frontal lobes followed by strong frontal carinae which are slightly divergent posteriad and then become nearly parallel; minimum distance between margin of ocular ridge and margin of compound eye less than half of major axis of compound eye; mandible relatively slender; masticatory margin with 6–9 distinct denticles; subapical tooth shorter than broad, with truncate apex; palp formula 4, 4. Mesosoma in lateral view relatively stout; pronotum including its anteromedian lobe short, in lateral view with anterodorsal slope relatively steep; mesopleuron without anteroventral ridge, with anterodorsal margin weakly carinate, clearly separated by distinct dorsal carina from mesonotum and metapleuron; propodeum in lateral view with dorsum slightly convex and gradually sloping posteriad, with posterior face steeply sloping; propodeal dorsum without median longitudinal depression. Petiole node conical, with sharply pointed apical spine; node in lateral view, excluding apical spine with anterior face weakly convex or weakly and bluntly angulate, and posterior face weakly convex; apical spine short and relatively slender, less than 1/4 as long as petiolar height, sometimes weakly curved posteriad (but shape variable within species); subpetiolar process anteroposteriorly shorter than dorsoventrally high, triangular, directed posteriorly. First gastral tergum in lateral view relatively long, with anterior face relatively short and vertical.

Head in full-face view largely smooth and shiny, but with striate area bordered by frontal carinae and ocular ridges; frontal lobe smooth and shiny; extraocular furrow smooth and shiny; median part of vertex along median furrow smooth and shiny; lateral face and venter of head smooth and shiny; median disc of clypeus smooth and shiny. Pronotal disc and mesonotum in dorsal view densely and transversely striate; posterolateral face of pronotum partly smooth and shiny; mesopleuron largely smooth and shiny, with anterior 1/4 and posteriormost part finely striate; metapleuron moderately striate in its anterior 2/3, and smooth and shiny or faintly striate in its posterior 1/3; propodeum with transverse striation which is a little sparser and stronger than on pronotum and mesonotum. Petiolar node largely smooth and shiny, but sometimes with its basal area faintly striate.

Vertex with a pair of long erect setae; frontal lobe without seta; pronotal disc without long erect setae; 1st gastral tergum without erect setae. Head, mesosoma, petiole and gaster with fine appressed pubescence which is sparse and very short on head and gaster.

For color pattern see in Fig. 8 ; head, mesosoma and gaster dark brown; all legs yellowish brown.

Characteristics seen in syntypes of “ O. latidens subsp. sumatranus ”. The morphological characteristics, excluding coloration, are almost completely the same between the syntypes of “ O. latidens subsp. sumatranus ” examined and the non-type workers listed above. In the syntypes the head, mesosoma and gaster are reddish brown and all legs are yellowish brown.

Queen measurements and indices. Holotype of O. procerus : HW 3.30 mm, HL 4.40 mm, SL 4.30 mm, IFLW 0.85 mm, EL 0.56 mm, OL 0.18 mm, MDL 2.46 mm, WL 5.68 mm, FWL 10.78 mm, PTL (unmeasurable), PTH (unmeasurable), CI 75, SI 130, MDI 55, PTHI (incalculable).

Syntypes of “ O. latidens subsp. sumatranus ” (n=2): HW 2.93 mm, HL 3.90 mm, SL 4.00 mm, IFLW 0.78 mm, EL 0.46–0.50 mm, OL 0.16–0.17 mm, MDL 2.29 mm, WL 4.90 mm, FWL unmeasurable (due to the dealation), PTL 0.79–0.81 mm, PTH 1.87–1.92 mm, CI 75, SI 136, MDI 59, PTHI 229–243.

Queen description. In general appearance queen is similar to worker. Vertex near ocelli not swollen; ocular ridge clearly developed; distance between lateral ocelli as long as distance between lateral and median ocelli, and as long as major axis of median ocellus; ocelli in lateral view protruded dorsad. Mesosoma with main sclerites associated with wing function ( Fig. 9 B), in dorsal view short and stout; anterodorsal slope of pronotum in lateral view steep; anterodorsal outline of mesoscutum in lateral view relatively steep; mesoscutum with very weak anteromedian depression (but posteromedian part of mesoscutum is deformed by pinning in holotype and syntypes); parapsidal furrow very weak and slightly curved; mesopleuron with fine, oblique furrow; propodeum in lateral view long with its dorsum almost straight and gradually sloping posteriad. Wing venation as in Fig. 9 D. Petiolar node in lateral view, excluding apical spines with anterior face weakly convex, and posterior face weakly convex; apical spine short and relatively slender, and weakly curved posteriad; subpetiolar process anteroposteriorly as long as dorsoventrally high. First gastral tergum in lateral view relatively short, with anterior face moderately long and vertical.

Head in full-face view largely smooth and shiny, but with striate area bordered by frontal carinae and ocular ridges; frontal lobe smooth and shiny; extraocular furrow faintly striate; median part of vertex along median furrow smooth and shiny; lateral face and venter of head largely smooth and shiny, but posterolateral and posteroventral faces faintly striate; median disc of clypeus smooth and shiny. Pronotum densely and weakly striate transversely; mesoscutum largely smooth and shiny, with faintly striate in anterior face and anteromedian depression; area along posterior margin of mesoscutum weakly striate; mesopleuron largely smooth and shiny, with anteriormost part faintly striate; mesoscutellum smooth and shiny; propodeum strongly and sparsely striate transversely. Petiolar node excluding apical spine largely smooth and shiny.

Pair of long erect setae present on vertex near lateral ocelli; frontal lobe and pronotal disc without erect setae; 1st gastral tergum without long erect setae. Head, mesosoma, petiole and gaster with sparse subdecumbent to decumbent pubescence which is extremely short on gaster; mesopleuron with very sparse pubescent.

For color pattern see in Fig. 9 ; head, mesosoma, petiole and gaster dark reddish brown; all legs light reddish brown.

Male measurements and indices. Non-types (n=8): HW 1.55–1.70 mm, HL 1.35–1.43 mm, SL 0.26–0.30 mm, EL 0.80–0.97 mm, EW 0.45–0.51 mm, OL 0.20–0.22 mm, OES 0.23–0.31 mm, WL 3.90–4.15 mm, FWL 6.86–7.64 mm, PTL 0.79–0.81 mm, PTH 0.93–1.08 mm, CI 114–121, SI 13–18, PTHI 117–128.

Male description. Size large (HL 1.35–1.43 mm, WL 3.90–4.15 mm). Major axis of median ocellus as long as minimum distance between lateral ocelli; antenna 13-merous; scape very short, 1/4 as long as 3rd antennomere; 2nd antennomere 1/2 as long as scape; 3rd to 13th antennomeres each extremely long; palp formula 6, 4; dorsal outline of clypeus in lateral view weakly convex. Mesosoma in lateral view relatively stout and long; dorsal outline of pronotum in lateral view almost straight; anterodorsal outline of mesoscutum in lateral view gently sloping; mesoscutum without median depression; parapsidal furrow weak and almost straight; oblique mesopleural furrow relatively shallow and narrow; ventrolateral part of katepisternum with a very weak longitudinal furrow; propodeum in lateral view with its dorsal outline roundly convex; metapleuron separated from propodeum indistinctly by suture; wing venation similar to queen (see Fig. 9 D for queen wings). Petiolar node broadly conical, with blunt apex; anterior slope of petiolar node in lateral view almost straight, and its posterior slope weakly convex; subpetiolar process in lateral view anteroposteriorly shorter than dorsoventrally high, triangular and much slender; petiolar sternum without posteroventral process. First gastral tergum in lateral view long; posterior spine of 8th abdominal tergum long and slender, very weakly curved (Fig. 18D); pygostyle with long setae in its apical 2/ 3; disc of 9th abdominal sternum almost circular, much longer than apical lobe, of which almost parallel lateral margins and weakly convex apex; telomeral apex in lateral view longer than high; distiventral apex of valviceps weakly produced; basiventral corner of valviceps not produced; ventral margin of valviceps with 27–31 denticles.

Head including area between lateral ocelli entirely smooth and shiny. Pronotum in dorsal view with rough texture and shiny; mesoscutum with rough texture and shiny; scuto-scutellar suture with sparse, strong, longitudinal rugae; mesopleural anepisternum and katepisternum smooth and shiny; propodeum with sparse, strong, longitudinal striate. Petiole smooth and shiny.

Head, mesosoma, legs, petiole and gaster with fine dense subdecumbent to decumbent pubescence; mandible, vertex near ocelli and gaster except 1st gastral tergum with several long setae.

For color pattern see in Fig. 10 ; petiole and gaster darker than head and mesosoma; scape yellowish brown and 3rd to 13th antennomeres darker than scape.

Species recognition. In 1893, Emery described O. latidens r. procerus from the Malay Peninsula based on the queen, and then, in 1900, he described O. latidens subsp. sumatranus from Sumatra based on the worker and queen. Both of the two forms were regarded as varieties of O. latidens , and were synonymized by Brown (1976) with the nominotypical subspecies of O. latidens (type locality: Java).

During our survey on Sumatran species of Odontomachus , we discovered colonies (containing workers, queens and males) which seemed to be relevant to O. latidens sensu lato. We compared these non-type queens with the holotype (queen) of “ O. latidens subsp. procerus ”; syntype queens of O. latidens subsp. sumatranus; and nontype queens from Java (colony JV02/03-SKY-39) which were identified by us as O. latidens based on Brown (1976). As a result of these comparisons we were able to separate two forms. The form “A” is characterized by the masticatory margin of the mandible with 6–9 distinct denticles that are reduced in size toward the base of the mandible, and the 1st gastral tergum without erect setae, and it is morphologically equivalent to the type material of “ O. latidens subsp. procerus ” and “ O. latidens subsp. sumatranus ”. On the other hand, the form “B” is characterized by the masticatory margin of mandible with very small denticles or sometimes without denticles (only preapical angle recognized), and the 1st gastral tergum with short erect setae that are shorter than those on vertex near ocelli. The form B is clearly different from the type material of “ O. latidens subsp. procerus ” and “ O. latidens subsp. sumatranus ” but agrees well with the non-type queens of “ O. latidens ” from Java. The forms A and B are also distinguishable from each other by the male morphology. The male of the form A is characterized by the following characters: body relatively dark; subpetiolar process in lateral view anteroposteriorly shorter than dorsoventrally high, triangular; posterior spine of 8th abdominal tergum long and slender, very weakly curved; disc of 9th abdominal sternum almost circular, much longer than apical lobe, of which almost parallel lateral margins and weakly convex apex; telomeral apex in lateral view longer than high. On the other hand, the male of the form B is characterized by the body relatively light in color; subpetiolar process in lateral view anteroposteriorly as long as dorsoventrally high, lobate; posterior spine of 8th abdominal tergum short and thick, very weakly curved; disc of 9th abdominal sternite not clearly differentiated from apical lobe, gradually merging into apical lobe, with basal margin almost straight; apical lobe gently tapering apicad, with apical margin truncated; telomeral apex in lateral view longer than high.

These differences between the two forms indicate a species-level delimitation between the two. Because we have not yet found the type material of O. latidens in any possible type depositories in Western countries, we are unable to confirm with certainty the identity of O. latidens . Thus, we provide here a tentative solution of this taxonomic problem: (1) the form A is identified as O. latidens subsp. procerus Emery, 1893 , and the taxon is revived and raised to species; (2) O. latidens subsp. sumatranus is synonymized with O. procerus ; and (3) the form B is, at present, treated as O. latidens .

Distribution. Indonesia (Sumatra) and Malaysia (Malay Peninsula, Sabah and Sarawak).

Bionomics. Odontomachus procerus inhabits secondary and primary forests in the highlands (between 800 and 1300 m alt., but one specimen in SKYC was collected from Sabah at an elevation of 550-610 m alt.), and it nests in the soil near the base of living trees. The colony SAGO-01-12 collected in Sago Mountain, West Sumatra, was collected nesting together with Pheidole inornata (colony SAGO-02-12). Details concerning the nature of their relationship are unknown.

DNA barcoding. The average K2P distance between O. procerus and O. latidens was 11.89% (SE=1.78%). This value falls within upper part of the full range of pairwise average interspecific distance: between 5.48% ( O. rixosus vs. O. pararixosus , SE=1.04%) and 14.38% ( O. simillimus vs. O. procerus , SE=1.84%) ( Table 1 ). The results support the species-level delimitation between O. procerus and O. latidens .

Figures

FIGURE 1. Petiole in lateral view, worker: A, Odontomachus latidens (colony: GK- 38 - 12; individual: SEMUT 150101 B); B, O. procerus (SAGO- 01 - 12; SEMUT 141217 B).

FIGURE 8. Odontomachus procerus, worker (colony: SAGO- 01 - 12; individual: SEMUT 141230 L): A, head in full-face view; B, mesosoma in dorsal view; C, mesosoma in lateral view; D, petiole and gaster in lateral view.

FIGURE 9. Odontomachus procerus, queen (holotype; ANTWEB CASENT 0903998): A, head in full-face view; B, profile in lateral view; C, label; D, forewing.

FIGURE 10. Odontomachus procerus, male (colony: SAGO- 01 - 12; individual: SEMUT 141215 B): A, head in full-face view; B, head in lateral view; C, head in dorsal view; D, mesosoma in lateral view; E, petiole in lateral view; F, mesosoma in dorsal view; G, gaster in lateral view.