Nesomyrmex flavus Csosz & Fisher

Csosz, Sandor & Fisher, Brian L., 2016, Taxonomic revision of the Malagasy Nesomyrmexmadecassus species-group using a quantitative morphometric approach, ZooKeys 603, pp. 105-130 : 112-114

Taxon classification Animalia Hymenoptera Formicidae

Nesomyrmex flavus Csosz & Fisher sp. n. Figs 4-6, Table 2

Type material investigated.

Holotype: CASENT0393113, collection code: BLF36563: MADAGASCAR, Prov. Toliara, Anosy Region, Anosyenne Mts, 31.2 km NW Manantenina, N -24.13894, E 47.06804, alt 1125 m, B.L. Fisher, F.A. Esteves et al., 2_26_2015, (1w, CAS);

Paratypes: Five workers, four gynes and two males with the same label data with the holotype under CASENT codes: CASENT0393110, collection code: BLF36563 (1w, 1q, CAS); CASENT0393111, collection code: BLF36563 (1w, 1q, CAS); CASENT0393112, collection code: BLF36563 (1w, 1q, CAS); CASENT0393113, collection code: BLF36563 (1q, CAS); CASENT0393114, collection code: BLF36563 (1w, 1m, CAS); CASENT0393115, collection code: BLF36563 (1w, 1m, CAS)

Material examined.

MADAGASCAR: CASENT0119576 (collection code: BLF14982, 1w, CAS, CASENT0119576): Prov. Fianarantsoa, Parc National Befotaka-Midongy, Papango 28.5 km S Midongy-Sud, Mount Papango, N -23.84083, E 46.9575, alt 1250 m, B.L. Fisher et al., 11_17_2006; CASENT0121813 (collection code: BLF15514, 1w, CAS, CASENT0121813): Prov. Toliara, Forêt Ivohibe 55.0 km N Tolagnaro, N -24.569, E 47.204, alt 200 m, B.L. Fisher et al., 12_3_2006; CASENT0129841 (collection code: BLF15450, 1w, CAS): Prov. Toliara, Forêt Ivohibe 55.0 km N Tolagnaro, N -24.569, E 47.204, alt 200 m, B.L. Fisher et al., 12_2_2006; CASENT0127625 (collection code: BLF01972, 2w, CAS): Prov. Antsiranana, Prov.Antsiranana R.S. Manongarivo 17.3 km 218° SW Antanambao, N -14.02167, E 48.4183, alt 1580 m, B.L. Fisher, 10_27_1998; CASENT0127641 (collection code: BLF00748, 1w, CAS): Prov. Fianarantsoa, 43 km S Ambalavao, Rés. Andringitra, N -22.23333, E 47, alt 800 m, B.L. Fisher, 10_6_1993; CASENT0127642 (collection code: BLF01023, 1w, CAS): Prov. Toamasina, 6.9 km NE Ambanizana, Ambohitsitondroina, N -13.56667, E 50, alt 1080 m, B.L. Fisher, 12_9_1993; CASENT0127643 (collection code: BLF00740, 1w, CAS): Prov. Fianarantsoa, 45 km S Ambalavao, N -22.21667, E 47.0167, alt 720 m, B.L. Fisher, 10_1_1993; CASENT0127646 (collection code: BLF01751, 2w, CAS): Prov. Fianarantsoa, R.S. Ivohibe, 6.5 km ESE Ivohibe, N -22.49667, E 46.955, alt 1575 m, B.L. Fisher (Sylvain), 10_24_1997; CASENT0141281 (collection code: BLF20452, 1w, CAS), CASENT0141284 (collection code: BLF20457, 2w, CAS): Prov. Fianarantsoa, Parc naturel communautaire, 26.8 km SW Ambositra, N -20.775, E 47.1836, alt 1755 m, B.L. Fisher et al., 5_20_2008; CASENT0148667 (collection code: BLF21477, 1w, CAS), CASENT0149902 (collection code: BLF21545, 1w, CAS): Prov. Toliara, Réserve Spéciale Kalambatritra, Betanana, N -23.4144, E 46.459, alt 1360 m, B.L. Fisher et al., 2_8_2009; CASENT0148948 (collection code: BLF21630, 1w, CAS), CASENT0148980 (collection code: BLF21600, 1w, CAS), CASENT0150536 (collection code: BLF21632, 1w, CAS), Prov. Toliara, Réserve Spéciale Kalambatritra, Ampanihy, N -23.4635, E 46.4631, alt 1270 m, B.L. Fisher et al., 2_9_2009; CASENT0151026 (collection code: BLF21705, 1w, CAS): Prov. Toliara, Réserve Spéciale Kalambatritra, Ampanihy, N -23.463, E 46.4706, alt 1269 m, B.L. Fisher et al., 2_10_2009; CASENT0189276 (collection code: BLF01626, 3w, CAS, CASENT0189276): Prov. Fianarantsoa, 29 km SSW Ambositra, Ankazomivady, N -20.77667, E 47.165, alt 1700 m, B.L. Fisher, 1_14_1998; CASENT0227040 (collection code: BLF1972(8), 1w, CAS), CASENT0227042 (collection code: BLF01014, 1w, CAS), CASENT0227044 (collection code: BLF01014, 1w, CAS): Prov. Toamasina, 6.9 km NE Ambanizana, Ambohitsitondroina, N -13.56667, E 50, alt 1080 m, B.L. Fisher, 12_9_1993; CASENT0409543 (collection code: BLF02398, 1w, CAS), CASENT0409544 (collection code: BLF02398, 1w, CAS), CASENT0409547 (collection code: BLF02398, 1w, CAS), CASENT0409582 (collection code: BLF02451, 2w, CAS), CASENT0409583 (collection code: BLF02421, 2w, CAS), CASENT0409585 (collection code: BLF02451, 2w, CAS), CASENT0409586 (collection code: BLF02435, 2w, CAS), CASENT0409587 (collection code: BLF02435, 1w, CAS), CASENT0409588 (collection code: BLF02465, 2w, CAS), CASENT0409590 (collection code: BLF02465, 2w, CAS), CASENT0409591 (collection code: BLF02447, 1w, CAS): Prov. Antananarivo, 3 km 41° NE Andranomay, 11.5 km 147° SSE Anjozorobe, N -18.47333, E 47.96, alt 1300 m, Fisher, Griswold et al., 12_5_2000; CASENT0418989 (collection code: BLF03695, 1w, CAS), CASENT0418990 (collection code: BLF03695, 1w, CAS), CASENT0418996 (collection code: BLF03695, 2w, CAS): Prov. Antananarivo, Réserve Spéciale d’Ambohitantely, Forêt d Ambohitantely, 20.9 km 72° NE d Ankazobe, N -18.22528, E 47.2868, alt 1410 m, Fisher, Griswold et al., 4_17_2001; CASENT0447182 (collection code: BLF05014, 1w, CAS), CASENT0447195 (collection code: BLF05014, 1w, CAS), CASENT0447265 (collection code: BLF05014, 1w, CAS), CASENT0447266 (col lection code: BLF05014, 1w, CAS), CASENT0447267 (collection code: BLF05014, 1w, CAS), CASENT0447269 (collection code: BLF05014, 1w, CAS): Prov. Toliara, Parc National d’Andohahela, Col du Sedro, 3.8 km 113° ESE Mahamavo, 37.6 km 341° NNW Tolagnaro, N -24.76389, E 46.7517, alt 900 m, Fisher-Griswold Arthropod Team, 1_21_2002; CASENT0477187 (collection code: BLF02543, 2w, CAS),; CASENT0488066 (collection code: BLF02544, 1w, CAS): Prov. Antananarivo, 3 km 41° NE Andranomay, 11.5 km 147° SSE Anjozorobe, N -18.47333, E 47.96, alt 1300 m, Griswold et al., 12_5_2000; CASENT0494106 (collection code: BLF09806, 1w, CAS),; CASENT0494153 (collection code: BLF09859, 2w, CAS): Prov. Antsiranana, Forêt de Binara, 9.4 km 235° SW Daraina, N -13.26333, E 49.6, alt 1100 m, B.L. Fisher, 12_5_2003;

Description of workers.

Body color: yellow. Body color pattern: Body concolorous. Absolute cephalic size: 602 [533, 699]. Cephalic length vs. Maximum width of head capsule (CL/CWb): 1.26 [1.19, 1.36]. Postocular distance vs. cephalic length (PoOc/CL): 0.48 [0.46, 0.50]. Postocular sides of cranium contour frontal view orientation: converging posteriorly. Postocular sides of cranium contour frontal view shape: convex. Vertex contour line in frontal view shape: straight; slightly concave. Vertex sculpture: main sculpture inconspicuous, ground sculpture smooth. Gena contour line in frontal view shape: convex. Genae contour from anterior view orientation: converging; strongly converging. Gena sculpture: NOT CODED. Concentric carinae laterally surrounding antennal foramen: present. Eye length vs. absolute cephalic size (EL/CS): 0.25 [0.23, 0.27]. Frontal carina distance vs. absolute cephalic size (FRS/CS): 0.30 [0.28, 0.32]. Longitudinal carinae on median region of frons: present. Longitudinal carinae on medial region of frons shape: variable. Smooth median region on frons: present. Antennomere count: 12. Scape length vs. absolute cephalic size (SL/CS): 0.80 [0.76, 0.83]. Median clypeal notch: variable. Ground sculpture of submedian area of clypeus: present. Median carina of clypeus: absent. Lateral carinae of clypeus: present. Metanotal depression: variable. Dorsal region of mesosoma sculpture: fine areolate ground sculpture, superimposed by dispersed rugae. Lateral region of pronotum sculpture: areolate ground sculpture, main sculpture dispersed costate. Mesopleuron sculpture: fine areolate ground sculpture, superimposed by dispersed rugulae. Metapleuron sculpture: fine areolate ground sculpture, superimposed by dispersed rugulae. Petiole width vs. absolute cephalic size (PEW/CS): 0.22 [0.21, 0.24]. Anterior profile of petiolar node contour line in lateral view shape: concave. Dorso-caudal petiolar profile contour line in lateral view shape: convex; strongly convex. Dorsal region of petiole sculpture: ground sculpture smooth, main sculpture absent. Postpetiole width vs. absolute cephalic size (PPW/CS): 0.35 [0.33, 0.40]. Dorsal region of postpetiole sculpture: ground sculpture smooth, main sculpture dispersed rugose; ground sculpture smooth, main sculpture absent.

Diagnosis.

Workers of Nesomyrmex flavus cannot be confused with Nesomyrmex gibber because the conspicuous mesothoracic hump which is a diagnostic character of the latter species is absent in Nesomyrmex flavus workers. This species can be easily separated from dark phenotypes of Nesomyrmex madecassus by color: the dark madecassus phenotypes are dark brown but the workers of Nesomyrmex flavus are light yellow. Morphometric ratio (PoOC/CW) and discri minant D4 function helps to separate Nesomyrmex flavus from ocher madecassus phenotypes; further details are given in diagnosis under Nesomyrmex madecassus .

The workers of this species are the most similar to that of Nesomyrmex nitidus . The elevational distribution of the two species may provide hints useful for separation (Fig. 3) but the ranges broadly overlap. These taxa represent true cryptic species which cannot be identified based on qualitative characters (i.e. sculpture, shape or color), and their overlapping range means ratios cannot be used for identification. Therefore, only a discriminant D2 function with a greatly reduced character set (D2 = +0.0847*SL -0.0625*MW -15.038) yields complete separation (morphometric data are in micrometer):

flavus D2 (n = 61) = +3.09 [+0.98, +5.33]

nitidus D2 (n = 79) = -2.39 [-4.63, +0.19]

For now, this remains the simplest method available to separate workers of these two taxa, but in the future, when more information about these species has been accumulated, we hope to find a reliable and easy-to-use diagnostic trait.

Biology and distribution.

This species is known to occur in Madagascar’s rain forests at high altitudes between 200 and 1755 m, mean: 1190 m (Fig. 3). This species is known to forage in low vegetation and nests can often be found in dead twigs. This species has occasionly been collectied in leaf litter (leaf mold, rotten wood), or in rotten tree stumps.