Camponotus aurosus Roger, 1863

Rakotonirina, Jean Claude & Fisher, Brian L., 2022, Revision of the Malagasy Camponotus subgenus Myrmosaga (Hymenoptera, Formicidae) using qualitative and quantitative morphology, ZooKeys 1098, pp. 1-180 : 1

Camponotus aurosus Roger

Figs 32A , 33A , 44

Camponotus aurosus Roger, 1863: 134. Syntype workers, Mauritius (Roger) (ZMHB); one syntype minor worker designated as lectotype, by present designation, AntWeb CASENT0104620 (ZMHB) [examined]. [Combination in Camponotus (Myrmepomis) : Emery, 1920a: 258; in Camponotus (Myrmosericus) : Forel, 1914: 268; Wheeler 1922: 1044].

Additional material examined.

Mauritius: [Mauritius, 19161], -20.3, 57.583333, (Roger) ( CAS); Bassin Blanc, -20.45463, 57.47587, 481 m: (L. Lach) ( CAS); Le Pouce, -20.195, 57.522222 (L. Lach) ( CAS); Le Pouce, -20.195, 57.522222 (C. M. Courtois) ( CAS); Macchabee Forest , -20.4, 57.45, 600 m, disturbed rainforest (P.S. Ward) ( MNHN); Petite Rivière Noire Mt. -20.40883, 57.40767, 750 m, rainforest (B.L. Fisher et al.) (UCDC); Petite Rivière Noire Mt., -20.363889, 57.368333 (Michael, Madl) ( CAS) . Reunion: Mare, Longue , -21.34617, 55.73983, 450 m, rainforest (B.L. Fisher et al.) (ZMHB); Mare Longue, -21.34889, 55.74417, 361 m, Low 1/2wet protected area (J. Casquet) ( CAS); Mare Longue, -21.35, 55.75, 150 m, primary forest (F. Blard) ( CAS); Mare Longue, -21.363344, 55.753428 (F. Blard) ( CAS) .

Diagnosis.

In full-face view, lateral margin of head anterior to eye level diverging posteriorly and covered with erect hairs; anterior clypeal margin broadly triangular or convex; mesosoma in profile short and high; gastral tergites covered with abundant pubescence; head and gaster black, mesosoma reddish orange to brown.

Description.

Minor worker. In full-face view, lateral cephalic margins diverging posteriorly, widest at eye level, rounding evenly to posterior margin; eye protruding and large (EL/CS: 0.27 ± 0.01; 0.25-0.29), breaking lateral margin of head, its posterior margin located at ca. posterior 1/4 of head (PoOc/CL: 0.24 ± 0.01; 0.22-0.26); frontal carinae widely opened posteriorly (FR/CS: 0.30 ± 0.01; 0.29-0.32), posteriorly diverging; clypeus without well-defined anterolateral angle, its anteromedian margin broadly convex or triangular; mandible with six teeth, the two apical teeth distant from each other; antennal scape relatively long (SL/CS: 1.33 ± 0.04; 1.27-1.40). Dorsal outline of mesosoma strongly arched, metanotal groove weakly visible; propodeal dorsum almost straight, joining the declivity at a blunt angle; propodeal declivity 3/4 length of the dorsum; petiolar node short, high, and tapering dorsally, its dorsal margin inclined posteriorly and forming a blunt angle with anterior face; anterior face of petiolar node 1/2 height of posterior face; tibia of hind leg rounded axially, without basal twist.

First and second gastral tergites without a pair of white spots; lateral margin of head anterior to level of eyes with a few erect hairs, which are absent behind level of eyes; antennal scape without erect hairs but covered with appressed hairs; pronotum with a pair of erect hairs; posterior cephalic margin with three or more pairs of erect hairs; posterodorsal angle of propodeum with two pairs of erect hairs.

Major worker. Differing from minor worker in the following characters: larger head (CS: 2.24 ± 0.11; 2.15-2.37; CWb/CL: 0.92 ± 0.03; 0.87-0.95), with broadly slight medial concavity on posterior margin; apical 1/3 of antennal scape surpassing posterior cephalic margin; with mesosoma in lateral view, length of propodeal dorsum the same as height of propodeal declivity; petiolar node more compressed anteroposteriorly.

Distribution and biology.

The distribution of C. aurosus is restricted to Mauritius and Reunion islands (Fig. 44D ). In these islands, this species occupies primary and disturbed rainforest habitats, where workers have been found foraging on the ground and on lower vegetation and nest sites have been located in rotten logs, in the ground, under stones, and in tree trunks.

Discussion.

Camponotus aurosus is similar to C. hagensii with respect to the shape of the head and the presence of erect hairs on the lateral cephalic margin, but the latter is characterized by the straight anteromedian margin of its clypeus, low and long mesosoma, and the presence of some pubescence on the gastral tergites.

The grouping of the C. aurosus samples in the same cluster shown by the dendrogram of multivariate morphometric analysis is corroborated by the cumulative LDA at 100% identification success. This result is congruent with that of the qualitative morphology-based study.

Figures

Figure 32. Head in full-face view A C. aurosus (CASENT 0064815) B C. gibber (CASENT 0188619).

Figure 33. Head in full-face view A C. aurosus (CASENT 0064815) B C. hagensii (CASENT 0191568).

Figure 44. Camponotus aurosus A lateral view B head in full-face view C dorsal view of minor worker CASENT 0064815 D distribution map.