Mexalictus (Mexalictus) mandibularis Dumesh, 2013

DUMESH, SHEILA, 2013, <p> <strong> Revision of the rare Mesoamerican bee genus <em> Mexalictus </ em> (Hymenoptera: Halictidae) with the description of </ strong> <br /> <strong> 21 new species </ strong> </ p>, Zootaxa 3708 (1), pp. 1-80 : 40-42

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Mexalictus (Mexalictus) mandibularis Dumesh

new species

Mexalictus (Mexalictus) mandibularis Dumesh , new species

( Figs. 126–131)

Holotype. Female. MEXICO, Chiapas, San Cristobal de las Casas, Huitepec , 2500m, N1644’50 W9241’21 3-iv- 2009, P. Sagot [ ECOSUR]; barcode accession number 03763E09-MEX.

Diagnosis. Both sexes of this species can be distinguished by the following combination: head and mesosoma dull to granular; clypeus uniformly punctate. The female could be diagnosed by the shiny and nearly impunctate lower paraocular area. The male is unique from all other species in the genus by the following: head wide with clypeus very short, gena much widened in lateral view, and mandible extremely elongate and slender without a subapical tooth. The female of this species is most similar to M. hansoni , M. hondurensis , and M. guatemalensis , but can be differentiated by the impunctate lower paraocular area (at least minutely punctate). The male of this species similar to M. genalis , M. laurencei , and M. mexicanus in having a large expanded and pointed gena in, but can be distinguished by the overall larger body size and the microserrate inner hind tibial spur (bluntly serrate).

Description. Female (Holotype): Body length 8.7–8.9mm, wing length 6.5–6.7mm, head width 1.82– 1.85mm, ITW 1.30mm. Head and mesosoma metallic dark green, pubescence pale, whitish. Head: slightly wider than long, L:W = 0.96:1. (1) Labrum and mandible: dark brown, with subrectangular basal area, medial length equal to half of width, flattened basal elevation, raised apical process, narrow triangular distal process; basal area of mandible dark brown, mandible red apically. (2) Clypeus: shiny, nearly half apical surface dark purple-brown; slightly shorter than supraclypeal area, extending about 0.95X length below lower eye margin, weakly convex in lateral view, protuberance about equal to supraclypeal area; punctures separated by 1–2pd, fine basally becoming coarser apically. (3) Supraclypeal area: as wide as to slightly wider than long, largest width subequal to length from upper clypeal margin to lower margin of antennal sockets; entirely granular, convex, protuberance greater than clypeus; punctation even basally and laterally, separated by 1–2pd, becoming sparse medially. (4) Lower paraocular area: dull above and towards supraclypeal area, shiny apically and laterally along inner margin of compound eye; punctures separated by 1–3pd except most of lower paraocular area where surface is shiny and impunctate along inner margin of compound eye below level of antennal sockets and below upper clypeal margin towards paraocular lobe. (5) Frontal area with frontal line carinate between antennae, slightly distinct above antennal sockets, becoming imarginate above, continuing up to medial ocellus, shiny impunctate triangle nearly absent; compound eye more convex below than above; punctation fine, extremely dense and crowded above antennae, punctures larger and more sparse below. (6) Vertexal area: shiny, with weak transverse depression; IOD = 2.5MOD, OOD = 3.0MOD, OVD = 1.8MOD; larger punctures separated by twice their diameter, smaller punctures closely spaced; punctuation more dense near eyes. (7) Genal and hypostomal areas: genal area narrower than eye in lateral view, about 0.75X, granular. (8) Antenna: dark brown, flagellum weakly reddish ventrally, scape, pedicel, and F1–F3 appearing darker than F4–F10; scape reaching posterior median ocellus, pedicel slightly longer than wide, F2 and F3 subequal in size, both wider than long and shorter than F1, flagellomeres slightly increasing in length distally, F10 longer than wide. Mesosoma: metallic reflections absent, (9) Pronotum: smooth, nearly impunctate, dull; posterodorsal margin of pronotum with complete band of hairs, including pronotal lobe which is densely outlined. (10) Mesoscutum: nearly dulled throughout, microsculpture more strongly imbricate along margins than in central disc where surface is somewhat shiny; punctures of 2 sizes, larger punctures deeper and separated by>4pd, smaller punctures shallow and more dense (2–3), very dense along parapsidal line (<1pd), becoming shallow and more obscure laterally where surface is much dulled. (11) Mesoscutellum: entirely dulled; punctation similar to those of mesoscutum, large punctures very sparse, small punctures most dense apically and along medial line which is basally depressed, extending nearly to apical. (12) Metanotum: entirely dulled, with punctures very obscure. (13) Mesopleuron: dull and granular, punctures sparse and evenly distributed, separated by>3pd; hypoepimeral area granular, finely punctate along upper margin, nearly impunctate below; pre-episternum with punctation similar to mesopleuron. (14) Metapleuron: transversely striate basally, otherwise weakly granular and somewhat shiny. (15) Metapostnotum and propodeum: length of metapostnotum slightly longer than apical width, apically rounded, dorsally bare, strongly granular basally, with very short longitudinal striation, weak or absent medially; propodeum becoming weakly shiny laterally and posteriorly. (16) Wings: clear, veins and stigma brown, membrane slightly infuscate; first recurrent vein meeting at or 1 vein width basad of second transcubital vein; second submarginal cell with anterior margin 2/3 length of posterior margin. (17) Tegula: dark brown; punctate anteriorly with few long branched hairs distally, posteriorly transparent, with hyaline, dull anterior margin. (18) Foreleg: dark brown; hairs pale golden on tarsi, metafemoral brush and anterior tibia; coxa, trochanter, and femur with branching shorter erect hairs; pubescence on tibia and basitarsus dense, hairs long, not branched. (19) Middle leg: as foreleg, hairs brownish on outer surfaces of tibia and basitarsus as well as basitibial plate; tibia with lateral patch of pale, long and dense pubescence on apical 2/3. (20) Hind leg: as middle leg, coxa and trochanter with long, branching, pale pubescence; femoral scopa well formed with long pale branching hairs; tibia densely pubescent, hairs dark, long and erect, mostly branched; basitarsus with several branched hairs among erect dark hairs, pubescence less dense than on tibia; femur 3X as long as greatest width; tibia 4X as long as greatest width; basitarsus 3.5X as long as greatest width; tibial spurs translucent yellow, apically darkened; inner hind tibial spur microserrate with over 15 fine, short teeth. Metasoma: reflections on metasomal terga weak to absent, (21) Terga: entirely shiny, nearly uniform in colour; metallic reflections absent; T1 entirely shiny and polished, nearly impunctate, T2–T4 with punctures separated by 2–3pd basally, becoming deeper and more sparse apically (>5pd), apical margins nearly impunctate, T5 with sparse and deeper punctures, separated by 4–6pd; pubescence pale on T1–T3 with short and thin hairs sparsely distributed throughout tergum and few dark hairs scattered laterally, pubescence dark and long on T4– T5, more dense than on T1–T3. (22) Sterna: ventral hairs long, plumose and pale, brownish on anterior surface of S5– S6, long pubescence on S1 near crossing with mesosoma; S2–S4 largest segments.

Male (Allotype): Body length 9.2–9.4mm, wing length 6.8–7.0mm, head width 2.0– 2.2mm, ITW 1.22– 1.25mm. Head and mesosoma green. Head: Wider than long, L:W = 0.83:1. (1) Labrum and mandible: basally, about 2.6 X as wide as long; rounded, smooth elevation extending length and width, medially flattened, may appear slightly indented; distal process extending beyond basal area for up to 0.5X length of labrum; mandible without subapical tooth, extremely elongate, reaching far beyond outer eye angle when closed. (2) Clypeus: metallic green basally, gradually becoming dark brown towards apical; short, about 3X as wide as long, with an apicomedial imargination, greatly protuberant centrally, becoming flattened laterally past paraocular lobe; punctures sparse throughout, separated by 2–4pd. (3) Supraclypeal area: granular, as wide as long, punctures separated by 1–2pd laterally and basally, becoming sparse medioapically. (5) Frontal area: frontal line only carinate between upper margin of antennal sockets and 1.5MOD below median ocellus; punctures dense and crowded from ocelli to level of antennal sockets, including interantennal space. (6) Vertexal area: dulled, mostly granular; IOD = 2.5MOD, OOD = 3.0MOD, OVD = 1.8MOD; punctures separated by 1–2pd medially, becoming sparser laterally towards compound eyes. (7) Genal and hypostomal areas: genal area shiny distally, slightly dull near compound eyes, distinctly wider than eye in lateral view, posteriorly expanded into broadly rounded projection; punctures fine and sparse, separated by 2–3pd above, becoming coarse and sparse below. (8) Antenna: reaching basal mesoscutellum; scape reaching median anterior ocellus; pedicel about as long as wide; flagellomere 1 slightly longer than pedicel, about as long as wide, longer than flagellomere 2, subequal in size to flagellomeres 3–10. Metasoma (21) Terga: metallic reflections absent; pygidial plate broadly rounded with elevated rim, depressed centrally, shiny and smooth, or with irregular rough areas. (22) Sterna: S4 with long plumose hairs medially directed on concave apicomedian area; S5 broadly concave centrally, medial plumose hairs longest apically, projecting ventrally as apical tuft, with small lateral patches of black hairs; S6 with a basal patch of apico-medially directed hairs. (23) Terminalia: see Figs. 130, 131.

Material examined. MEXICO, Chiapas , San Cristobal de las Casas, Huitepec, 2500m, N1644’50 W9241’21 3-iv-2009, P. Sagot (holotype female [ ECOSUR]); San Cristobal de las Casas, Huitepec, 11-ii-2008 (allotype male [ ECOSUR], barcode label 03763H07- MEX); Chiapas , San Cristobal de las Casas, Huitepec, 2550m, N1644’42 W9241’05 27-i-2009, P. Sagot (paratype male [ ECOSUR], barcode label 03763F12- MEX) .

Etymology. This species is named for the long mandibles characteristic of the male. Although males of most species of Mexalictus possess longer mandibles than their respective females, the mandibles of M. mandibularis are extremely long, slender, and pointed.


El Colegio de la Frontera Sur (Mexico)