Synopsis of species of the Pheidole bessonii group

Pheidole antsahabe sp. nov.

Pheidole atsirakambiaty sp. nov.

Pheidole bessonii Forel, 1891

Pheidole clara sp. nov.

Pheidole decollata Forel, 1892 stat. nov.

Pheidole flammea sp. nov.

Pheidole flavodepressa sp. nov.

Pheidole grallatrix Emery, 1899

Pheidole madecassa Forel, 1892

Pheidole mantadioflava sp. nov.

Pheidole maro sp. nov.

Pheidole oswaldi Forel, 1891

Pheidole ovalinoda sp. nov.

Pheidole similis sp. nov.

Pheidole tenebrovulgaris sp. nov.

Pheidole uranus sp. nov.

Pheidole voreios sp. nov.

Pheidole zirafy sp. nov.

Taxonomy

The following repetitive characters occurring in the majority of species have been omitted from the individual species accounts. Unless stated otherwise, the following descriptions apply to all species treated here:

Major workers. Dorsal face of head in lateral view not depressed posteriorly; antennal socket shallow; frontal lobe absent; head in full-face view with distinct posteromedian concavity; antenna 12-segmented with 3-segmented club; masticatory margin of mandible with large, stout apical tooth and preapical tooth, followed by long diastema and then short and crenulate tooth just before rounded basal angle; outer surface of mandible mostly smooth and shining, sometimes with weak and sparse puncta; antennal scrobe absent; promesonotum strongly convex, well above level of propodeum; postpetiole shiny and microreticulate, short with slightly convex dorsum, in dorsal view oval with lateromedian dentate projection, pilosity erect; petiole shiny and microrugulate, peduncle with small horizontal lobes on its basal part, node triangular with rounded top, in rear view node dorsoventrally concave, pilosity erect.

Minor workers. Antennal socket shallow, surrounded with few indistinct wrinkles that curve posterolaterally, most often with sculptured interspaces; frontal lobe absent; head in full-face view oval, posterior and anterior of compound eye convex; antenna 12-segmented with 3-segmented club; humeral tubercle not developed into projection; clypeus smooth and shiny; anterior margin regularly convex; promesonotum well above level of propodeum; petiole smooth with ventral face slightly convex, node triangular with few erect setae; postpetiole smooth, convex with few erect setae; gaster smooth and shiny.

Revision of the Pheidole bessonii group

Diagnosis. Major worker. Postpetiole in profile without conspicuous ventral convexity; antennal socket shallow; frontal lobe absent or indistinct; propodeal spine moderate to large, wide to narrow; head in full-face view sub-rectangular, with lateral margins varying from relatively straight to slightly convex, not or slightly widening posteriorly; head in lateral view sub-oval with distinctly convex dorsal and ventral cephalic margins; occipital lobe never with transverse costulae and usually entirely sculptured (except P. madecassa, P. maro and P. uranus); frons entirely sculptured, medially costulate to rugocostulate, lateral sides with usually weaker sculpture; antennal scrobe absent or very indistinct; costulae and rugulae on the rest of head thick to very thin; promesonotum short, angular, and moderately low to very low; mesonotal process usually distinct; postpetiole in dorsal view with lateromedian dentate projection; gaster usually at least partially shagreened. Minor worker. Postpetiole in profile without conspicuous ventral convexity; antennal socket shallow; frontal lobe absent or indistinct; propodeal spine minute to moderately large, wide to narrow; promesonotum in lateral view never box-like and posterior mesonotum never steep; promesonotal groove present and distinct (except P. tenebrovulgaris); posterior region of head usually elongated, forming short to long neck; nuchal collar present and weakly developed to distinct (except P. madecassa and P. maro); promesonotum moderately low to very low and moderately long to very long, and arched.

Comments. The P. bessonii group consist of species widely distributed on the island. Six species— P. bessonii, P. decollata, P. grallatrix, P. maro, P. oswaldi and P. tenebrovulgaris can be considered common. The remaining 12 species have more restricted distributions primarily limited to the northern and northeastern parts of the island. The majority of the major and minor workers of the bessonii group can be easily separated from other taxa based on the combination of the above-mentioned characters. However, majors of P. madecassa and P. maro can be confused with major workers of the longispinosa group. They can be separated based on distinctly shorter propodeal spines, denser frons sculpture, and brighter body coloration. Additionally, minors of P. tenebrovulgaris can be confused with two members of the sikorae group: P. trichotos Salata & Fisher and P. veteratrix Forel. Pheidole tenebrovulgaris can be separated based on larger body size, longer propodeal spines, higher promesonotum, and dark brown body coloration. There is also one member of the bessonii group known from Mayotte: P. ragnax . Because its original description is comprehensive and the species is not recorded from Madagascar, we decided not to include it in our revision. However, we included it in comparative diagnoses within the descriptions of most similar species.

Key to the Pheidole bessonii group

1 Major worker. Head, in full face view, slightly widening posteriorly and occipital lobe mostly smooth or head not widening posteriorly and occipital lobes with rugae that never arch posterolaterally, body never yellow or orange, head never with short and dense setae (Fig. 2). Minor worker. Posterior part of head not to slightly elongated but never forming a neck, and nuchal collar absent to weakly developed (Fig. 3).................................................................. 2

- Major worker. Head not or slightly widening posteriorly, occipital lobe and sometimes frons with rugae or costulae that arch posterolaterally distinctly to indistinctly. If occipital lobes with rugae then body yellow to orange or brown with lateral sides of head with short, dense setae (Fig. 6). Minor worker. Posterior part of head elongated and often forming a neck, nuchal collar distinct (Fig. 7)....................................................................................... 8 Note. Major worker of P. ovalinoda and P. flammea have occipital lobes with distinct rugae and dark body coloration. The best character to distinguish between these taxa is the difference in pilosity on the side of head. Pheidole ovalinoda has sides of head with short, decumbent to suberect setae while P. flammea has sides of head with long, suberect to erect setae. If characters match P. ovalinoda then go to couplet #2; if characters match P. flammea then go to couplet #8.

2 Major worker. Occipital lobes with thick and moderately dense rugae with mostly smooth interspaces, outer hypostomal tooth absent to weakly developed (Figs 2E, 4G). Minor worker. Petiolar peduncle moderately short and thick and node high, postpetiole short and moderately high (Fig. 5E).................................................... Pheidole ovalinoda

- Major worker. Occipital lobes mostly smooth or with thin and moderately sparse rugae with interspaces most often sculptured, outer hypostomal tooth present and distinct (Figs 2 A–D, F, G, 4E, F). Minor worker. Petiolar peduncle moderately long and thin and node low, postpetiole longer and flat (Fig. 5 A–D, F, G).................................................... 3

3 Major worker. Occipital lobes with thin rugae and indistinctly punctate to smooth interspaces, side of head with moderately dense, short, appressed to subdecumbent pilosity, body dark brown (Fig. 2F). Minor worker. Promesonotal groove absent to indistinct, mesosoma entirely punctate, body dark brown. (Fig. 5F)......................... Pheidole tenebrovulgaris

- Major worker. Occipital lobes mostly smooth or occipital lobes punctate with sparse and indistinct rugae, sides of head with dense, long, suberect to erect pilosity and body yellowish orange to brown (Fig. 2 A–D, G). Minor worker. Promesonotal groove present and distinct, mesosoma sparsely punctate to smooth, body yellow to yellowish brown (Fig. 5 A–D, G)............ 4

4 Major workers. Occipital lobes never with reduced sculpture or smooth notches (Fig. 2A, D). Minor workers. Posterior part of head slightly elongated, mesosoma mostly punctate (Figs 3A, D, H, K, 5A, D)..................................... 5

- Major worker. Occipital lobes entirely or mostly smooth (Fig. 2B, C, G). Minor worker. Posterior part of head never elongated and mesosoma mostly or entirely smooth (Figs 3B, C, G, I, J, N, 5B, C, G)....................................... 6

5 Major worker. Promesonotum in lateral view moderately long, angular, and very low (Fig. 4D), inner hypostomal tooth small (Fig. 27L). Minor worker. Occiput slightly elongated, promesonotum moderately long, angular, and very low (Figs 3D, K, 5D)................................................................................... Pheidole oswaldi

- Major worker. Promesonotum in lateral view short, angular, and moderately low (Fig. 4A), inner hypostomal tooth moderately large (Fig. 27E). Minor worker. Occiput not elongated, promesonotum moderately long, angular, and moderately low (Figs 3A, H, 5A)................................................................................ Pheidole decollata

6 Major worker. Lateral frons densely rugose-reticulate, occipital lobes mostly smooth, posteriorly with sparse and weakly developed rugae (Fig. 2G). Minor worker. Occiput slightly elongated; nuchal collar weakly developed (Fig. 3G, N)................................................................................................ Pheidole uranus

- Major worker. Frons laterally smooth with sparse rugulae, occipital lobes smooth, sometimes with weakly developed rugopuncta (Fig. 2B, C). Minor worker. Occiput not elongated, nuchal collar absent (Fig. 3B, C, I, J)...................... 7

7 Major worker. Antennal scrobe with sparse and very thin rugulae with indistinctly punctate interspaces, mesosoma weakly microreticulate, inner hypostomal tooth large, body reddish brown (Figs 2C, 4C, F). Minor worker. Frons and mesosoma with very sparse, weakly developed puncta (Figs 3C, 5C).............................................. Pheidole maro

- Major worker. Antennal scrobe with sparse, very thin rugulae with smooth interspaces, mesosoma smooth with very indistinct and thin rugulae, inner hypostomal tooth small, body yellow to orange (Figs 2B, 4B, E). Minor worker. Frons and mesosoma smooth, only anterolateral frons with weakly developed puncta (Figs 3B, 5B)..................... Pheidole madecassa

8 At least minor worker yellow to orange.................................................................... 9

- Minor and major worker bright brown to brownish black..................................................... 13

9 Major worker. Head elongated, posteromedian concavity very deep, CI> 112.0, HL> 1.8 mm (Fig. 6F). Minor worker. Head with moderately long and narrow neck (Fig. 7F, Q)........................................ Pheidole flavodepressa

- Major worker. Head not elongated, posteromedian concavity deep, CI <112.0, HL <1.8 mm (Fig. 6A, D, H, I). Minor worker. Head with short and moderately thick neck (Fig. 7A, D, H, I, L, O, S, T)........................................ 10

10 Major worker. Body brown, costulae on posterior frons arching posterolaterally (Fig. 6A). Minor worker. Promesonotum with weakly developed network of sparse microreticulae (Fig. 8A)................................... Pheidole antsahabe

- Major worker. Body yellow to orange, costulae on posterior frons never arching posterolaterally (Fig. 6D, H, I). Minor worker. Promesonotum smooth or distinctly punctate (Fig. 8D, H, I).................................................. 11

11 Major worker. Head with lateral sides relatively straight, frons laterally with thick rugocostulae and rugulate interspaces (Fig. 6I). Minor worker. Promesonotum smooth, frons mostly smooth (Figs 7I, 8I).......................... Pheidole similis

- Major worker. Head with lateral sides slightly convex, frons laterally sparsely rugopunctate (Fig. 6D, H). Minor worker. Promesonotum punctate, frons weakly punctate (Figs 7D, H, 8D, H)................................................. 12

12 Major worker. Antennal scrobes very indistinct, mostly punctate with additional network of thin and sparse rugae, anterior mesonotum placed slightly higher than pronotum (Figs 6H, 8N). Minor worker. Frons with sparse puncta, propodeal spines small with wide base (Figs 7H, 8H)......................................................... Pheidole mantadioflava

- Major worker. Antennal scrobes absent, frons laterally with thick and dense rugae with distinctly punctate interspaces, anterior mesonotum placed lower than pronotum (Figs 6D, 8L). Minor worker. Only anterolateral frons with sparse puncta, propodeal spines small and thin (Figs 7D, 8D)............................................................ Pheidole clara

13 Major worker. Occipital lobes with thick, sparse rugae with smooth interspaces, frons laterally with thick, dense rugae with smooth to indistinctly rugulate interspaces (Fig. 6E). Minor worker. Head with short and moderately narrow neck (Fig. 7E, P).................................................................................... Pheidole flammea

- Major worker. Occipital lobes with very thin, dense rugae, most often with sculptured interspaces, frons laterally with thin, dense rugae with distinctly sculptured interspaces (Fig. 6B, C, G, J, K). Minor worker. Head without a neck or with a long and narrow neck (Fig. 7B, C, G, J, K, M, N, R, U, V)........................................................... 14

14 Major worker. Head elongated, posteromedian concavity very deep, HL> 2.4 mm, CI> 110.0 or head not elongated and posteromedian concavity deep and mesosoma mostly smooth (Figs 6G, K, 8M, O). Minor worker. Head with long and narrow neck (Fig. 7G, K, R, V).................................................................................... 15

- Major worker. Head not elongated, posteromedian concavity deep, and mesosoma entirely sculptured, HL <2.4 mm, CI <110.0 (Figs 6B, C, J, 10D). Minor worker. Head without neck. (Fig. 7B, C, J, M, N, U).................................. 16

15 Major worker. Head elongated, posteromedian concavity very deep, and mesosoma entirely sculptured (Figs 6K, 8O). Minor worker. Neck very long, promesonotal and propodeal dorsum mostly smooth with sparse, transverse rugae, propodeal side and mesopleuron densely rugoreticulate (Figs 7K, V, 8K)............................................. Pheidole zirafy

- Major worker. Head not elongated and posteromedian concavity deep, mesosoma mostly smooth (Figs 6G, 8M). Minor worker. Neck long, mesosoma smooth (Figs 7G, R, 8G).............................................. Pheidole grallatrix

16 Major worker. Body black, frons and occipital lobes with moderately thick, moderately dense costulae that arch posterolaterally, interspaces between costulae smooth to indistinctly rugopunctate (Fig. 6B). Minor worker. Body black, frons punctate with few rugae, mesosoma distinctly punctate (Figs 7B, 8B).................................... Pheidole atsirakambiaty

- Major worker. Body brown, at least frons laterally more rugulate, frons and occipital lobes with distinctly punctate to rugopunctate interspaces (Fig. 6C, J). Minor worker. Body yellowish brown to blackish brown, frons usually with strongly reduced sculpture and with smooth notches, mesosoma with smooth notches (Figs 7C, J, 8C, J)............................. 17

17 Major worker. Occipital lobes with moderately thin and sparse rugulae that arch posterolaterally, interspaces between rugulae punctate, frons laterally with sparse costulae with distinctly punctate interspaces (Fig. 6J). Minor worker. Occiput elongated, mesosoma microreticulate, promesonotum with sparse microreticulae, promesonotal dorsum mostly to entirely smooth, propodeal spines small and narrow (Figs 7J, 8J)..................................................... Pheidole voreios

- Major worker. Occipital lobes punctate, sometimes with thin and very sparse rugulae that arch posterolaterally, frons laterally with sparser, thinner rugocostulae with distinctly punctate interspaces (Fig. 6C). Minor worker. Occiput not elongated or elongated very slightly, promesonotum mostly smooth, lateral mesosoma sparsely microreticulate, propodeal spines very small with relatively wide base (Figs 7C, 8C).......................................................... Pheidole bessonii

Species accounts