Carebara phragmotica Fischer, Azorsa & Hita Garcia

Fischer, Georg, Azorsa, Frank, Garcia, Francisco Hita, Mikheyev, Alexander S. & Economo, Evan P., 2015, Two new phragmotic ant species from Africa: morphology and next-generation sequencing solve a caste association problem in the genus Carebara Westwood, ZooKeys 525, pp. 77-105 : 93-99

Taxon classification Animalia Hymenoptera Formicidae

Carebara phragmotica Fischer, Azorsa & Hita Garcia sp. n. Figs 1A, B, 6, 7

Holotype.

phragmotic worker, KENYA, Kakamega Forest, Colobus trail, 000.3551389°, 34.8583611°, 1650m, rainforest, leaf litter, 14.vi.2007 (M. Peters) (ZFMK: CASENT0709551).

Paratypes.

3 major workers (same data as holotype) (CASENT0906158, CASENT0709548, CASENT0709549); 2 phragmotic workers, Kakamega Forest, Kaimosi fragment, 00.128°, 034.84°, 1600m, rainforest, leaf litter, 04.viii.2008 (G. Fischer) (CASENT0709550, CASENT0738556); 1 phragmotic worker, Kakamega Forest, Malawa fragment, 00.4617889°, 034.8587333°, 1650m, rainforest, leaf litter, viii.2007 (F. Hita Garcia) (CASENT0277301); 1 phragmotic worker, Kakamega Forest, Yala, 0.202°, 34.868°, 1650m, rainforest, leaf litter, v.2008 (M. Peters) (CASENT0738559); 2 major workers, Kakamega Forest, Malawa fragment, 00.4543611°, 034.8635556°, rainforest, leaf litter, 01.ix.2005 (G. Fischer) (CASENT0709552, CASENT0709553); 5 minor workers, 1 phragmotic worker, Kakamega Forest, Kisere fragment, 0.385278°, 34.892417°, 1650m, rainforest, leaf litter, 25.xi.2005 (G. Fischer) (CASENT0709554, CASENT0709555, CASENT0709556, CASENT0709557, CASENT0709558); 2 minor workers, Kakamega Forest, Salazar, 00.3266667°, 034.8707222°, 1650 m, rainforest, leaf litter, 09.iii.2009 (M. Peters) (CASENT0709559, CASENT0217819); 2 minor workers, Kakamega Forest, Isecheno, 00.235°, 34.869°, 1650m, rainforest, leaf litter, 28.viii.2007 (F. Hita Garcia) (CASENT0709560, CASENT0709561); 2 major, 2 minor workers, Kakamega Forest, Kisere fragment (CASENT0709594, CASENT0709595, CASENT0709596, CASENT0709597).

Diagnosis.

Phragmotic worker: Cephalic shield with two subparallel, conspicuously elevated ridges in its center, in profile distinctly elevated above the rim of the shield. Anterolateral lobes of cephalic shield shorter than and ending before anterior border of clypeal lobes. Major worker: Frons and anterior sides of head with abundant, narrow longitudinal rugulae, near posterior head margin a few irregular, weakly defined, transverse rugulae present. Minor worker: Head subrectangular (CI 84-88), hind femur moderately short (FI 72-78), postpetiole as long as high or longer (LPpI 100-120) and on average about 1.45 times wider than petiole (PpWI 136-150).

Description of phragmotic major workers.

Measurements (n=3): HW 0.68-0.71 (0.70), HL 0.76-0.79 (0.78), SL 0.15-0.23 (0.21), MDL 0.14-0.20 (0.17), EL 0.02, WL 0.78-0.79 (0.79), PNW 0.48-0.50 (0.49), PTL 0.32-0.33 (0.32), PPL 0.15-0.18 (0.17), PTH 0.21-0.22 (0.22), PPH 0.19-0.20 (0.19), PTW 0.20-0.21 (0.21), PPW 0.26-0.27 (0.26), PSL 0.10-0.12 (0.11), MFL 0.39-0.41 (0.40), MTL 0.31-0.32 (0.31), CI 89-90 (89), SI 21-34 (30), MDI 20-28 (24), EI 2, FI 57-59 (58), PSLI 14-17 (15), LPpI 80-96 (88), DPpI 142-170 (156), PpWI 126-129 (127), PpLI 48-55 (52), PpHI 86-90 (88).

Head in full-face view almost as wide as long (CI 89-90), with a phragmotic cephalic shield, outline of shield oval, sharply margined, anterolaterally with short, semi-transparent lobes. Anterior margin of clypeus widely transverse with anteriorly projecting lateral lobes, slightly surpassing the laterally overlapping lobes of the shield.

Cephalic shield with two wavy, sub-parallel, raised ridges centrally, surrounded by several radiating and irregular, shorter canyons and ridges. The inside of the cephalic shield is normally covered with a layer of dirt. Mandibles small, compact (MDI 20-28), and when tightly closed partly hidden under anteriorly projecting clypeus and ce phalic shield. Head-shape in profile anteriorly straight along border of cephalic shield, the head appearing like a thick, anteriorly flattened door or plug. Antennal scrobe hidden under anterolateral lobes of cephalic shield. Antennae ten-segmented, short, with reduced scape length as compared to other major workers (SI 21-34), in full-face view largely hidden under cephalic shield. Eyes strongly reduced, consisting of one small ommatidium (EI 2), situated at the posterior end of scrobe.

In profile view, promesonotum high and convex, posteriorly sloping linearly towards a short, separated or anteriorly fused, posteriorly sharply margined scutellum, in dorsal view comparable to a polished convex shield. Promesonotal suture absent or inconspicuous, scutellum small and weakly to not isolated in dorsal view, metanotum present as a small bump extending dorsally between propodeum and scutellum, metanotal groove narrowly impressed. Propodeal dorsum short, anteriorly convex, with a blunt angle halfway towards the short, bluntly triangular to rounded propodeal teeth, posterior declivity oblique, with short and narrow lamella and well developed, lamellate propodeal lobe. Propodeal spiracle circular, situated close to center of lateropropodeum.

Petiole in profile with relatively short peduncle, ventrally straight to weakly convex, with small to reduced anterior tooth, lateroventral margins posteriorly with very thin, elongate lamellae present, the node sub-triangular and dorsally rounded to very broadly wedge-shaped, postpetiole in profile higher than long (LPpI 80-96) and almost as high as petiole (PpHI 86-96), its dorsum convex and with a very short ventral face. In dorsal view, petiole node shape transversely oval, wider than long and posteriorly flattened, postpetiole wider than long, suboval, anterior margin concave and posterior margin almost straight, about 1.3 times wider than petiole (PpWI 126-129).

Mandibles, clypeus and most of the cephalic shield finely shagreened, highest areas on central ridges smooth and shiny. Posterior of cephalic shield, near head margin, shagreening overlain with weakly reticulate rugulae, posterior head margin with weakly raised carina and small horns present at posterolateral corners. Ventral side of head very finely and obliquely striate. Promesonotum, parts of anepisternum and katepisternum, postpetiole dorsum and gaster mostly smooth and shiny, remainder of body punctate.

Lateral and posterior portions of head with very short, erect to suberect hairs, no visible hairs on cephalic shield, mesosoma with relatively sparse, fine, relatively short, decumbent pilosity, and few longer, subdecumbent to suberect fine hairs. Waist segments and gaster covered with very abundant pilosity, apical segments of gaster also with many suberect, long standing hairs. Scape and tibiae pilosity abundant and decumbent. Color light or reddish brown, antennae, legs and parts of gaster, yellow.

Description of major workers.

Measurements (n=5): HW 0.59-0.63 (0.61), HL 0.74-0.78 (0.76), SL 0.27-0.30 (0.29), MDL 0.32-0.34 (0.33), EL 0.03, WL 0.64-0.67 (0.65), PNW 0.36-0.39 (0.37), PTL 0.26-0.27 (0.26), PPL 0.14-0.17 (0.15), PTH 0.19-0.20 (0.21), PPH 0.17-0.19 (0.18), PTW 0.18-0.20 (0.19), PPW 0.23-0.25 (0.23), PSL 0.08-0.10 (0.09), MFL 0.34-0.38 (0.36), MTL 0.26-0.29 (0.28), CI 79-82 (80), SI 46-49 (47), MDI 53-55 (54), EI 5, FI 58-62 (59), PSLI 13-15 (14), LPpI 80-92 (87), DPpI 141-160 (152), PpWI 119-133 (126), PpLI 56-61 (58), PpHI 86-96 (90).

Head in full-face view rectangular, about 1.25 times longer than wide (CI 79-82), sides subparallel, posterior margin with transverse carina present on either sice of narrow, evenly concave median emargination, horns small and obtuse, posterolateral corners rounded. Mandibles triangular, about half as long as head width, masticatory margin with five teeth including basal tooth. Frontal carinae absent or inconspicuous. Anterior margin of clypeus concave medially and laterally on either side of median concavity. Frons sometimes with median ocellus present. Antennae with ten segments. Scapes short and when laid back not surpassing cephalic midlength (SI 46-49). Eyes present, consisting of one relatively large ommatidium (EI 5).

In profile, pronotum high and convex, posteriorly declining linearly, propodeum distinctly higher than long, dorsal face obliquely declining, posterior corners either edentate and angulate or with very small triangular teeth, posterior declivity nearly vertical with very shallow lamella, propodeal lobes relatively small. Pronotum in dorsal view strongly rounded and almost circular, pronotal suture on dorsum inconspicuous or present as weak impression, scutellum very small and often fused with pronotum, metanotal groove present, barely or not impressed, propodeal spiracle circular, situated almost at center of lateropropodeum.

Petiole in profile with short peduncle, almost subtriangular in shape, posteroventrally weakly convex, anteriorly with small tooth or subpetiolar process. Petiole node dorsally flat to weakly convex, in dorsal view much wider than long, its posterior end well defined to weakly marginate. Postpetiole in profile higher than long (LPpI 80-92), almost as high as petiole (PpHI 86-96), convex dorsally, and with a small, angulate ventral process. In dorsal view postpetiole wider than long, suboval with rounded sides, on average 1.3 times wider than petiole (PpWI 119-133).

Mandibles smooth and shiny with scattered, short, appressed pilosity and weak, short rugulae laterally near their bases. Head with very fine and densely packed longitudinal striations, near posterior margin replaced by irregular transverse rugulae, with a conspicuously raised and transversely curved carina laterally of median concavity. Mesosoma and petiole mostly weakly punctate, except for smooth and shiny promesonotal dorsum and parts of lateropronotum, with rugosities at junctions of pronotum, anepisternum, katepisternum and metapleuron. Postpetiole dorsally smooth and shiny, its remainder punctate. Gaster smoth and shiny.

Head and body with abundant, moderately long, decumbent to subdecumbent pubescence and with few suberect hairs. Scape and tibia pilosity abundant and decumbent. Color brown to light brown, antennae, legs and parts of gaster, slightly lighter.

Description of minor workers.

Measurements (n=5): HW 0.32-0.34 (0.33), HL 0.38-0.39 (0.38), SL 0.23-0.25 (0.24), MDL 0.20-0.28 (0.23), EL 0.02, WL 0.38-0.39 (0.39), PNW 0.21-0.23 (0.22), PTL 0.14-0.16 (0.15), PPL 0.08-0.09 (0.08), PTH 0.11-0.12 (0.12), PPH 0.08-0.09 (0.08), PTW 0.08-0.09 (0.08), PPW 0.11-0.12 (0.11), PSL 0.05, MFL 0.24-0.26 (0.25), MTL 0.19-0.20 (0.19), CI 84-88 (86), SI 70-75 (73), MDI 60-82 (69), EI 4-7 (6), FI 72-78 (74), PSLI 13-15 (14), LPpI 100-120 (105), DPpI 133-150 (140), PpWI 136-150 (145), PpLI 53-61 (56), PpHI 67-74 (70).

Head longer than wide (CI 84-88), in full–face view weakly subrectangular, sides convex, posterior margin nearly straight to faintly convex. Anterior margin of clypeus straight medially, weakly bicarinate, and narrow between antennal insertions. Frontal carinae very weakly developed, ending at or before eye level. Antenna with ten segments, scapes, when laid back, ending well before posterior head margin (SI 70-75). Eyes small (EI 4-7), consisting of one ommatidium, situated slightly anterior to cephalic midline.

In profile, promesonotum convex, metanotal groove impressed, propodeal dorsum weakly convex, shorter than posterior declivity, declining posteriorly towards small, acute to bluntly triangular, lamellate propodeal teeth, declivity of propodeum oblique, with narrow lamella connecting the teeth and relatively large propodeal lobes. Propodeal spiracle circular and situated close to posterior border of propodeum, just below the propodeal teeth.

Petiole in profile view with a short peduncle, with a convex ventral bulge, anteriorly with a short, triangular tooth, petiole node dorsally roundly subtriangular. Postpetiole relatively short and low, as long as high or slightly longer (LpPI 100-120), lower than petiole (PpHI 67-74), dorsum convex. In dorsal view petiole node about as wide as long, postpetiole subrectangular with rounded corners, about 1.45 times wider than petiole (PpWI 136-150).

Mandibles and clypeus smooth and shiny. Face smooth and shiny, near antennal insertion with weak concentric carinae, frontal carinae very short and reduced. Promesonotum, postpetiole dorsum, most of propodeal declivity, and gaster smooth and shiny, metapleuron, propodeum and petiole areolate.

Whole body with abundant, relatively short, decumbent pilosity. Clypeus and body with very few erect to suberect hairs present. Scape pilosity short, decumbent to subdecumbent, tibia pilosity mostly decumbent. Color orange to light brown, with yellowish antennae and legs.

Distribution.

This species is known only from Kakamega Forest and its smaller fragments in the north (Malawa and Kisere Forest) and in the south (Kaimosi Forest), in the Western Province of Kenya.

Discussion.

Carebara phragmotica is different from Carebara elmenteitae (Patrizi), which was collected in leaf-litter on the banks of the river Kariandus near Lake Elementeita in the Great Rift Escarpment in Kenya ( Patrizi 1948), and that has been described from a single phragmotic worker. Interestingly the specimen was identified as a queen, but according to its’ description and the drawing it very closely resembles the phragmotic major workers of Carebara phragmotica sp. n. and Carebara lilith sp. n. Despite their high morphological similarity, the phragmotic majors of these three species can be separated from each other by the following head characters: horns at posterior head margin and anterolateral lobes of clypeus lacking or indistinct in Carebara elmenteitae versus horns distinct in Carebara phragmotica and Carebara lilith , and the clypeal lobes anteriorly surpassing the lateral lobes of the relatively small cephalic shield lobes in Carebara phragmotica versus the cephalic shield lobes significantly larger and anteriorly surpassing the clypeal lobes in Carebara lilith . Finally, the cephalic shield in Carebara elmenteitae contains low, irregular rugulae or ridges, versus the two highly raised, subparallel central ridges, that, in profile, are distinctly higher than the rim of the cephalic shield in Carebara phragmotica , whereas Carebara lilith is characterized by a mostly flat cephalic shield surface without ridges or canyons, instead with punctures and small, cone-shaped structures present.

Minor workers of Carebara phragmotica can be differentiated from those of Carebara lilith by the characters listed in the diagnosis (see discussion of Carebara lilith ). Minor and major workers of Carebara phragmotica can be distinguished from those of Carebara thoracica by their antennal segmentation (ten segments in phragmotica versus nine in thoracica ).

Etymology.

This species’ name is derived from the modified head morphology of the phragmotic major workers.