Chelostoma ( Chelostoma ) miripalpum Müller, 2025

Müller, Andreas, Pisanty, Gideon & Dorchin, Achik, 2025, Western Palaearctic Chelostoma bees of the subgenus Chelostoma (Megachilidae, Osmiini): biology, taxonomy and key to species, Zootaxa 5717 (3), pp. 329-369 : 349-351

Chelostoma ( Chelostoma) miripalpum Müller , sp. nov.

Holotype. TURKEY: Adana: Pozantı , 10.5.– 15.5.1955, 1♂ (leg. Seidenstücker). Deposited in the Entomological Collection of ETH Zurich.

Paratypes. IRAQ: Dahuk: Mount Gara, 1912 m, 37.015833 ° N / 43.350556 ° E, 11.5.2023, 6♂ (leg. D. Baiocchi), Mount Gara , 5 km E Ashewa 1750–1950 m, 37.0158 ° N / 43.3505 ° E, 30.5.– 12.6.2024, 1♀ (leg. D. Baiocchi). Deposited in the Entomological Collection of ETH Zurich .

Diagnosis. The females of C. miripalpum can be separated from those of the other two species of the C. meronense group by the following combination of characters: i) head about 1.4 as long as wide, ii) proboscis reaching coxa of middle leg in repose, iii) second segment of labial palpus slightly more than 2 as long as compound eye, iv) third segment of labial palpus about 2.5× as long as fourth segment ( Fig. 42 ), v) labrum about 2× as long as apically wide, v) basal area of propodeum medially slightly longer than metanotum ( Fig. 43 ), and vi) anterior surface of coxa of fore leg medially sparsely punctate with interspaces reaching the diameter of several punctures. The males differ from the related species by the following combination of characters: i) hypostomal area without tooth-like projection, ii) third segment of labial palpus about 2.5× as long as fourth segment, iii) antennal segments 8–12 symmetrical and longer than wide ( Fig. 44 ), iv) last antennal segment cylindrical ( Fig. 44 ), v) antenna entirely dark brown to black ( Fig. 44 ), vi) basal area of propodeum medially slightly longer than metanotum, vii) anterior margin of median projection of sternum 2 evenly rounded ( Fig. 47 ), and viii) patches of short black thorns of sternum 3 restricted to rather small spots on each side of sternal impression ( Fig. 48 ).

Description. FEMALE ( Fig. 40 ): Body length 7.5 mm. Head: Head about 1.4× as long as wide. Distance between posterior margin of lateral ocellus and occipital margin about 1.5× as long as ocellar diameter. Clypeus rather strongly convex, its anteriormost point slightly projecting over supraclypeal area in lateral view. Punctation of clypeus laterally and apically dense with interspaces hardly exceeding diameter of one puncture and on narrow median zone more scattered with interspaces reaching diameter of two punctures. Supraclypeal area basally and laterally densely and medioapically sparsely punctate. Labrum about 2× as long as apically wide; its apical margin shallowly emarginate over entire width. Mandible three-toothed. Proboscis very long ( Fig. 40 ), reaching coxa of middle leg when folded; second segment of labial palpus about 5.5× as long as first segment and about 2.1× as long as compound eye. Third segment of labial palpus about 2.5× as long as fourth segment ( Fig. 42 ). Antenna uniformly dark brown to black. Mesosoma : Posterior and lateral surface of propodeum largely polished. Basal area of propodeum medially slightly longer than metanotum, flat, crossed by numerous rather fine longitudinal carinae and bordered by narrow impunctate polished zone around its posterior margin ( Fig. 43 ). Anterior surface of coxa of fore leg medially very sparsely punctate with interspaces reaching the diameter of several punctures. Apical margin of tibial spur of fore leg prolonged into very short tip. Tibial spurs of hind leg brownish. Metasoma: Marginal zones of terga 1–4 with dense and short white hair bands ( Fig. 40 ), which are usually not interrupted in fresh specimens. Terga 2–3 basally not or only weakly constricted. Scopa white, its hairs not plumose ( Fig. 40 ).

MALE ( Fig. 41 ): Body length 8–8.5 mm. Head: Head about 1.1× as long as wide. Distance between posterior margin of lateral ocellus and occipital margin 1.4–1.5× as long as ocellar diameter. Hypostomal area without tubercles or tooth-like projections and genal area along lower margin of compound eye not impressed and densely punctate. Proboscis very long ( Fig. 41 ), reaching coxa of middle leg when folded; second segment of labial palpus 5–5.5× as long as first segment and 1.7-1.85× as long as compound eye. Third segment of labial palpus about 2.5× as long as fourth segment. Antennal segments 5–12 symmetrical and longer than wide ( Fig. 44 ). Last antennal segment cylindrical ( Fig. 44 ). Antenna uniformly dark brown to black ( Fig. 44 ). Mesosoma : Posterior and lateral surface of propodeum largely polished. Basal area of propodeum medially slightly longer than metanotum, flat, crossed by numerous rather fine longitudinal carinae and bordered by narrow impunctate polished zone around its posterior margin. Mesosternum medioapically with narrowly triangular impression, the margins of which are only weakly raised. Anterior surface of coxa of fore leg medially sparsely punctate with interspaces reaching the diameter of several punctures. Apical margin of tibial spur of fore leg slightly emarginate. Metasoma: Marginal zones of terga 1–5(6) with loose white hair bands ( Fig. 41 ), which are widely interrupted on terga 1–3(4). Terga 2–3 basally not or only weakly constricted. Tergum 7 basally with oval pit, laterally triangularly toothed and apically with two teeth, which are roughly parallel-sided, about as long as to slightly longer than basally wide, apically (obliquely) truncate and separated from each other by a roughly rectangular space two to three times as wide as tooth width ( Fig. 45 ). Ventral base of apical teeth of tergum 7 with large backwardly and inwardly directed tooth-like projection, the tip of which is clearly visible when tergum 7 is viewed from above ( Fig. 45 ). Apical margin of sternum 1 medially distinctly emarginate. Median projection of sternum 2 half-elliptical and concave in ventral view, its anterior half evenly rounded in ventral view and largely overhanging concave anterior surface of median projection in lateral view ( Fig. 46, 47 ). Sterna 2–3 lateroapically with tuft of long white hairs. Sternum 3 with two small spots of short black thorns on each side of apical sternal impression, which is anteriorly bordered by arched transversal swelling ( Fig. 48 ). Sternum 3 with row of stiff yellowish bristles along its apical margin ( Fig. 48 ). Sternum 4 densely covered with whitish pilosity, which surpasses apical margin and is apically curled downwards. Apical margin of sternum 5 with single row of long, yellowish and moniliform bristles. Sternum 6 roughly quadrangular in shape, its apical half polished, very sparsely haired, impunctate and medially impressed.

Distribution. Southern central Turkey, northern Iraq ( Fig. 74 ).

Pollen hosts. Unknown, but presumably oligolectic on Lamiaceae by analogy to C. meronense .

Nesting biology. Unknown.

Etymology. The species epithet refers to the unusually long segment 3 of the labial palpus (lat. “mirus” =

remarkable, amazing), which is a unique character in C. ( Chelostoma ).

Figures

FIGURE 74. Distribution of the eight Chelostoma species newly described in the present publication: C. dolichocephalum (violet), C. kurdistanicum (orange), C. levantense (white), C. meronense (dark blue), C. miripalpum (light blue), C. negevense (red), C. ornithogali (yellow) and C. scabiosae (green). Made with Natural Earth (ww w.naturalearthdata.com).

FIGURES 40–48. Chelostoma miripalpum: 40: Female, 41: Male, 42: Labial palpi of female, 43: Basal area of propodeum of female, 44: Antenna of male, 45: Terga 5–7 of male, 46: Sternum 2 of male in lateral view, 47: Median projection of sternum 2 of male in ventral view, 48: Sternum 3 of male.