taxonID	type	description	language	source
DE79FF2B7D12FFC95C8791ABFE2A897F.taxon	materials_examined	Holotype. SAUDI ARABIA: Riyadh: 20 km W Huraymila, 25.151 ° N / 45.929 ° E, 800 m, 25.3.2025, ♀ (leg. M. Halada). Deposited in the Entomological Collection of ETH Zurich. Paratypes. SAUDI ARABIA: Riyadh: Riyadh, King Saudi University Campus, 24.633031 ° N / 46.716358 ° E, 9.2.2015, 2 ♂ (leg. M. Shebl); Riyadh, Derab, Agricultural Research Station, 24.488222 ° N / 46.619850 ° E, 12.2.2015, 1 ♀ (leg. M. Shebl); S Riyadh, 24.425 ° N / 46.653 ° E, 6.3.2024, 1 ♂ (leg. M. Halada); Ulya, 100 km NW Riyadh, 25.281 ° N / 46.021 ° E, 9.3.2024, 1 ♂ (leg. M. Halada); Al Hair SE Riyadh, 24.392 ° N / 46.793 ° E, 520 m, 24.3.2025, 1 ♂ (leg. M. Halada). Deposited in the Entomological Collection of ETH Zurich.	en	Müller, Andreas, Shebl, Mohamed A., Alqarni, Abdulaziz S. (2026): Three new osmiine bee species from the extreme desert of Saudi Arabia with specialized pollen-collecting behaviours (Megachilidae, Osmiini). Zootaxa 5782 (2): 330-346, DOI: 10.11646/zootaxa.5782.2.5, URL: https://doi.org/10.11646/zootaxa.5782.2.5
DE79FF2B7D12FFC95C8791ABFE2A897F.taxon	diagnosis	Diagnosis. Hoplitis heliotropii belongs to the subgenus Hoplitis. Within this subgenus, it is a member of the H. adunca species group as shown by the presence of a submarginal carina along the (latero) apical margin of sternum 6 in the female and by the apically rounded, truncate or only shallowly emarginate tergum 7 in the male. The 6.5 – 7 mm long female of H. heliotropii (Fig. 1) differs from all other species of the H. adunca group by the long and apically curved bristles that cover the first and the second segment of the labial palpus (Fig. 4, 5, 36). Similar bristles on the labial palpus also occur in the females of H. (Hoplitis) persica and H. (Hoplitis) premordica, which belong to the H. persica species group. The species of this group differ from H. heliotropii by the absence of a submarginal carina along the (latero) apical margin of sternum 6 and by the two- rather than four-segmented labial palpus, which represents a unique character among the osmiine bees. Additional characters of the female of H. heliotropii are i) the strongly convex clypeus, which is laterally densely punctate with interspaces hardly exceeding the diameter of half a puncture and medially crossed by an unpunctured longitudinal line of varying length (Fig. 3), ii) the equal length of the first and the second segment of the labial palpus, iii) the reddish coloured anterior (and partly also posterior) side of the antennal segments 4 – 11, iv) the largely truncate apical margin of the tibial spur of the fore leg with a barely recognizable tiny tooth (Fig. 6), v) the yellowish-white, long, slender and straight hind tibial spurs, whose apex is only very weakly curved, vi) the distinctly reddish coloured marginal zone of the terga 1 - 5, and vii) the sparse, appressed and whitish pilosity covering tergum 6. The 5.5 – 7 mm long male of H. heliotropii (Fig. 2) is characterized by the combination of the following four characters: i) first segment of the labial palpus 0.85 – 0.95 × as long as the second segment, ii) apical margin of the tibial spur of the fore leg with a tiny tooth, which is not longer than basally wide and often barely recognizable in worn specimens, iii) lateral lobes of the bilobed membraneous appendage of sternum 6 densely haired, slightly longer than wide and separated from each other by a deep triangular incision (Fig. 8), and iv) gonoforceps abruptly bent inwards and downwards in its apical third (Fig. 9). Additional characters of the male are v) the presence of single long hairs on the ventral side of the first (and less pronounced also of the second) segment of the labial palpus, vi) the simple antennal flagellum consisting of regularly cylindrical segments, which are about as long as wide except for segments 12 and 13, which are slightly and distinctly longer than wide, respectively (Fig. 7), vii) the orange coloured anterior (and largely also posterior) side of the antennal segments (3) 4 – 12 (13) (Fig. 7), and viii) the distinctly reddish coloured marginal zone of the terga 1 – 6.	en	Müller, Andreas, Shebl, Mohamed A., Alqarni, Abdulaziz S. (2026): Three new osmiine bee species from the extreme desert of Saudi Arabia with specialized pollen-collecting behaviours (Megachilidae, Osmiini). Zootaxa 5782 (2): 330-346, DOI: 10.11646/zootaxa.5782.2.5, URL: https://doi.org/10.11646/zootaxa.5782.2.5
DE79FF2B7D12FFC95C8791ABFE2A897F.taxon	description	Description. FEMALE (Fig. 1): Body length 6.5 - 7 mm. Head: Head about 0.85 × as long as wide. Distance between posterior margin of lateral ocellus and preoccipital margin 1.05 – 1.15 × as long as ocellar diameter. Maximum width of genal area about 0.5 × as long as maximum width of compound eye. Clypeus strongly convex, laterally densely punctate with interspaces hardly exceeding the diameter of half a puncture and medially crossed by a narrow and unpunctured longitudinal line of varying length (Fig. 3); its apical margin denticulate. Mandible three-toothed and largely black. Pilosity of frons, supraclypeal area, paraocular area and gena white, rather long, moderately dense and suberect to partly appressed on supraclypeal and paraocular area; pilosity of basal half of clypeus long, sparse and semierect to erect, of apical half rather dense, suberect to appressed and distinctly surpassing clypeal margin (Fig. 3). First and second segment of labial palpus equally long and covered with long and apically curved bristles (Fig. 4, 5, 36). Anterior (and partly also posterior) side of antennal segments 4 – 11 reddish coloured. Antennal segment 3 about 1.25 × as long as wide. Mesosoma: Parapsidal line long-linear. Punctation of scutum, scutellum and mesepisternum dense with interspaces not exceeding the diameter of half a puncture to one puncture. Basal area of propodeum shagreened. Pilosity of mesosoma whitish. Tegula yellowish-brown to yellowish-red except for black inner and anterior margin; its anterior half and inner margin moderately densely punctured, its posterior half almost unpunctured. Stigma and veins of fore wing (dark) brown to black. Apical margin of tibial spur of fore leg largely truncate with a barely recognizable tiny tooth (Fig. 6). Tibial spurs of hind leg yellowish-white, long, slender, largely straight and apically only very weakly curved. Pilosity of inner surface of basitarsus of hind leg yellowish-white. Metasoma: Punctation of tergal discs 2 – 4 medially rather fine and sparse with interspaces reaching the diameter of up to two to three punctures. Punctation of terga 5 – 6 denser with interspaces rarely exceeding the diameter of one puncture. Marginal zone of terga 1 – 5 distinctly reddish coloured. Terga 1 – 4 (5) with short white hair bands, which are medially not interrupted in fresh specimens (Fig. 1). Longest erect hairs on median half of tergum 1 as long as maximal length of lateral hair tuft. Tergum 6 covered with sparse, appressed and whitish pilosity. Sternum 6 medioapically not prolonged into distinct spine and laterally with low and sharp submarginal carina. Scopa whitish. MALE (Fig. 2): Body length 5.5 – 7 mm. Head: Head about 0.75 × as long as wide. Distance between lateral ocellus and preoccipital margin about 1.3 × as long as ocellar diameter. Maximum width of genal area 0.5 – 0.6 × as long as maximum width of compound eye. Mandible two-toothed and of black colour except for dark reddish-brown apical teeth. Apical margin of clypeus denticulate. Face and gena including ventral side covered with dense white pilosity, which is partly appressed on supraclypeal and paraocular area. First segment of labial palpus 0.85 – 0.95 × as long as second segment. Ventral side of first (and less pronounced also of second) segment of labial palpus with single long hairs. Flagellum of antenna simple and consisting of regularly cylindrical segments, which are about as long as wide except for segments 12 and 13, which are slightly and distinctly longer than wide, respectively (Fig. 7). Anterior (and largely also posterior) side of antennal segments (3) 4 – 12 (13) orange coloured (Fig. 7). Mesosoma: Parapsidal line long-linear. Punctation of scutum, scutellum and mesepisternum dense with interspaces rarely exceeding the diameter of one puncture except for central zone of scutum and scutellum, where punctation is slightly more scattered. Basal area of propodeum shagreened. Pilosity of mesosoma whitish. Tegula yellowish-brown to yellowish-red except for black inner margin, its anterior half fine and sparsely punctured, its posterior half impunctate. Stigma and veins of fore wing yellowish-brown to brown. Apical margin of tibial spur of fore leg with tiny tooth, which is not longer than basally wide and often barely recognizable in worn specimens. Tibial spurs of hind leg yellowish-white, slender, largely straight and apically only very weakly curved. Metasoma: Punctation of tergal discs 2 – 4 medially rather fine and sparse with interspaces reaching the diameter of up to two to three punctures. Punctation of terga 5 – 6 denser with interspaces rarely exceeding the diameter of one and a half punctures. Marginal zone of terga 1 – 6 distinctly reddish coloured. Marginal zone of terga 1 – 5 with short white hair bands, which are not interrupted in fresh specimens (Fig. 2). Protruding median part of apical margin of tergum 6 crenulate and / or with shallow to rather deep median emargination. Tergum 6 laterally with distinct narrowly triangular tooth. Tergum 7 apically evenly rounded (rarely with very shallow median emargination), its lateral margin ventromedially with small angular projection. Apical margin of sterna 1 – 4 almost straight to medially very slightly emarginate and beset with rather long and sparse whitish pilosity, which is shortest on sternum 4. Apical margin of sternum 5 slightly rounded (rarely with very shallow median emargination) and almost hairless (Fig. 8). Marginal zone of sterna 2 – 5 reddish coloured and usually with fine and rather dense punctation, distinctly contrasting with the very sparse punctation of tergal discs 3 – 5 (Fig. 8). Sternal discs 2 – 5 with medially narrowed and on sternum (4) 5 interrupted transversal swelling (Fig. 8). Sternum 6 at base with pair of large translucent flaps (Fig. 8). Lateral lobes of bilobed membraneous appendage of sternum 6 densely haired, slightly longer than wide and separated from each other by a deep triangular incision (Fig. 8). Gonoforceps abruptly bent inwards and downwards in its apical third (Fig. 9).	en	Müller, Andreas, Shebl, Mohamed A., Alqarni, Abdulaziz S. (2026): Three new osmiine bee species from the extreme desert of Saudi Arabia with specialized pollen-collecting behaviours (Megachilidae, Osmiini). Zootaxa 5782 (2): 330-346, DOI: 10.11646/zootaxa.5782.2.5, URL: https://doi.org/10.11646/zootaxa.5782.2.5
DE79FF2B7D12FFC95C8791ABFE2A897F.taxon	distribution	Distribution. Known so far only from Riyadh province in central Saudi Arabia (Fig. 10).	en	Müller, Andreas, Shebl, Mohamed A., Alqarni, Abdulaziz S. (2026): Three new osmiine bee species from the extreme desert of Saudi Arabia with specialized pollen-collecting behaviours (Megachilidae, Osmiini). Zootaxa 5782 (2): 330-346, DOI: 10.11646/zootaxa.5782.2.5, URL: https://doi.org/10.11646/zootaxa.5782.2.5
DE79FF2B7D12FFC95C8791ABFE2A897F.taxon	etymology	Etymology. The species epithet refers to the boraginaceous genus Heliotropium, which is an important host plant of H. heliotropii.	en	Müller, Andreas, Shebl, Mohamed A., Alqarni, Abdulaziz S. (2026): Three new osmiine bee species from the extreme desert of Saudi Arabia with specialized pollen-collecting behaviours (Megachilidae, Osmiini). Zootaxa 5782 (2): 330-346, DOI: 10.11646/zootaxa.5782.2.5, URL: https://doi.org/10.11646/zootaxa.5782.2.5
DE79FF2B7D15FFCA5C8790F3FE418FE3.taxon	materials_examined	Holotype. SAUDI ARABIA: Riyadh: Al Hair SE Riyadh, 24.392 ° N / 46.793 ° E, 520 m, 24.3.2025, ♂ (leg. M. Halada). Deposited in the Entomological Collection of ETH Zurich. Paratypes. ISRAEL: Southern District: Totes Meer, En Boqeq, 31.199589 ° N / 35.362004 ° E, 5.3.1996, 1 ♂ (leg. W. H. Liebig); Dead Sea, En Zeelim 5 km N Massada, 31.381236 ° N / 35.333378 ° E, 7.5.1996, 1 ♀ (leg. C. Schmid-Egger); En Yahaf, 30.653469 ° N / 35.221417 ° E, 19.3.2010, 1 ♂ (leg. Y. Hops), 15.4.2010, 1 ♀ (leg. A. Gotlieb), 4.5.2010, 1 ♀ (leg. A. Gotlieb); 3 km E Ne › ot Smadar, 30.036116 ° N / 35.043717 ° E, 23.4.2010, 1 ♀ (leg. C. Sedivy, C. Praz); 1 km SW Elifaz, 29.781361 ° N / 34.987759 ° E, 24.4.2010, 1 ♀ (leg. C. Sedivy, C. Praz); 2 km N Ein Yahav, 30.674756 ° N / 35.238156 ° E, 28.4.2010, 2 ♀ (leg. C. Sedivy, C. Praz), 29.4.2010, 2 ♀ (leg. C. Sedivy, C. Praz); Nahal Ya’alon N Yahel, 30.0875 ° N / 35.1291667 ° E, 201 m, 5.4.2016, 3 ♀ (leg. A. Dorchin). SAUDI ARABIA: Hail: Al Maghwat near Magooah Centre, 27.372569 ° N / 41.175006 ° E, 21.3.2013, 2 ♀, 2 ♂ (leg. M. A. Hannan); Jabal Mashar, Valley 1 km from parking place, 27.525808 ° N / 41.618130 ° E, 100 m, 21.3.2013, 1 ♀ (leg. M. A. Hannan); Jabal Mashar, Al Rifai valley 1 km from parking place, 27.525808 ° N / 41.618130 ° E, 150 m, 22.3.2013, 1 ♀ (leg. M. A. Hannan); Riyadh: Riyadh, King Saudi University Campus, 24.633031 ° N / 46.716358 ° E, 9.2.2015, 1 ♂ (leg. M. Shebl), 11.2.2015, 1 ♂ (leg. M. Shebl); Riyadh, Derab, Agricultural Research Station, 24.488222 ° N / 46.619850 ° E, 2.3.2015, 2 ♀, 2 ♂ (leg. M. Shebl); Al Hair SE Riyadh, 24.392 ° N / 46.793 ° E, 520 m, 24.3.2025, 1 ♂ (leg. M. Halada). Deposited in the Entomological Collection of ETH Zurich.	en	Müller, Andreas, Shebl, Mohamed A., Alqarni, Abdulaziz S. (2026): Three new osmiine bee species from the extreme desert of Saudi Arabia with specialized pollen-collecting behaviours (Megachilidae, Osmiini). Zootaxa 5782 (2): 330-346, DOI: 10.11646/zootaxa.5782.2.5, URL: https://doi.org/10.11646/zootaxa.5782.2.5
DE79FF2B7D15FFCA5C8790F3FE418FE3.taxon	diagnosis	Diagnosis. Hoplitis trichodesmae belongs to the subgenus Hoplitis. Within this subgenus, it is a member of the H. adunca species group, which is characterized by the presence of a submarginal carina along the (latero) apical margin of sternum 6 in the female and by the apically rounded, truncate or only shallowly emarginate tergum 7 in the male. Among the species of H. (Hoplitis), H. trichodesmae is in both sexes immediately recognizable by the relative lengths of the first and the second segment of the labial palpus (Fig. 14): the first segment is 1.15 – 1.25 × as long as the second segment, whereas in all other H. (Hoplitis) species the first segment is shorter than the second segment. The only exception is the female of H. heliotropii (see above), whose first segment of the labial palpus is of about the same length as the second segment. This species, however, is easily recognizable among all species of the H. adunca group by the presence of specialized pollen-collecting bristles on the labial palpus. Additional characters of the 5.5 – 7 mm long female (Fig. 11) are i) the strongly convex clypeus, which lacks a distinct longitudinal midline and is densely punctured with interspaces hardly exceeding the diameter of half a puncture (Fig. 13), ii) the usually dark to light reddish coloured anterior (and partly also posterior) side of the antennal segments 4 – 11, iii) the largely orange coloured tegula, which is sparsely punctured over its entire surface (Fig. 16), iv) the yellowish-white, long, slender and straight hind tibial spurs, whose apex is only very weakly curved, v) the longitudinally striate base of the basal area of the propodeum (Fig. 15), vi) the distinctly reddish coloured marginal zone of the terga 1 - 5, and vii) the sparse, appressed and whitish pilosity covering tergum 6. Additional characters of the 5.5 – 7.5 mm long male (Fig. 12) are i) the simple antennal flagellum consisting of regularly cylindrical segments, which are longer than wide and vary in colour from predominantly brownish to largely reddish (Fig. 17), ii) the largely orange coloured tegula, which is sparsely punctured over its entire surface, iii) the longitudinally striate base of the basal area of the propodeum, iv) the distinctly reddish-coloured marginal zone of the terga 1 – 6 (Fig. 18), v) the medially very shallowly emarginate apical margin of tergum 7 (Fig. 18), and vi) the densely haired roundish lobes of the bilobed membraneous appendage of sternum 6, which are separated by a polished and hairless zone (Fig. 19).	en	Müller, Andreas, Shebl, Mohamed A., Alqarni, Abdulaziz S. (2026): Three new osmiine bee species from the extreme desert of Saudi Arabia with specialized pollen-collecting behaviours (Megachilidae, Osmiini). Zootaxa 5782 (2): 330-346, DOI: 10.11646/zootaxa.5782.2.5, URL: https://doi.org/10.11646/zootaxa.5782.2.5
DE79FF2B7D15FFCA5C8790F3FE418FE3.taxon	description	Description. FEMALE (Fig. 11): Body length 5.5 – 7 mm. Head: Head about 0.85 × as long as wide. Distance between posterior margin of lateral ocellus and preoccipital margin 1.65 – 1.75 × as long as ocellar diameter. Maximum width of genal area 0.55 – 0.65 × as long as maximum width of compound eye. Clypeus strongly convex, without a distinct longitudinal midline and densely punctured with interspaces hardly exceeding the diameter of half a puncture (Fig. 13); its apical margin denticulate. Mandible three-toothed and largely black except for preapical zone, which is more or less dark reddish-brown. Pilosity of frons, supraclypeal area, paraocular area and gena whitish, moderately long, rather sparse and suberect to partly appressed on supraclypeal and paraocular area; clypeus covered on its central zone with inconspicuous, short and whitish pilosity not hiding its cuticle and on its apical zone with long, rather sparse and whitish pilosity distinctly surpassing clypeal margin (Fig. 13). First segment of labial palpus 1.2 – 1.25 × as long as second segment (Fig. 14). Anterior (and partly also posterior) side of antennal segments 4 – 11 dark to light reddish coloured. Antennal segment 3 about 1.6 × as long as wide. Mesosoma: Parapsidal line long-linear. Punctation of scutum, scutellum and mesepisternum dense with interspaces not exceeding the diameter of half a puncture to one puncture. Basal area of propodeum shagreened and basally longitudinally striate (Fig. 15). Pilosity of mesosoma whitish. Tegula yellowish-brown to yellowish-red except for black inner margin and sparsely punctured over its entire surface (Fig. 16). Stigma and veins of fore wing brown to dark brown. Apical margin of tibial spur of fore leg extended into long spine, which is longer than basally wide. Tibial spurs of hind leg yellowish-white, long, slender, largely straight and apically only very weakly curved. Pilosity of inner surface of basitarsus of hind leg yellowish-white. Metasoma: Punctation of tergal discs 2 – 4 medially rather sparse to moderately dense with interspaces reaching the diameter of up to two, rarely three punctures. Punctation of terga 5 – 6 denser with interspaces rarely exceeding the diameter of one to one and a half punctures. Marginal zone of terga 1 – 5 distinctly reddish coloured. Terga 1 – 5 with short white hair bands, which are medially interrupted on terga 1 – 2 (3) except for very fresh specimens (Fig. 11). Longest erect hairs on median half of tergum 1 about half as long as maximal length of lateral hair tuft or shorter. Tergum 6 covered with sparse, appressed and whitish pilosity. Sternum 6 medioapically not prolonged into distinct spine and laterally with low and sharp submarginal carina. Scopa whitish. MALE (Fig. 12): Body length 5.5 – 7.5 mm. Head: Head about 0.8 × as long as wide. Distance between lateral ocellus and preoccipital margin about 1.75 × as long as ocellar diameter. Maximum width of genal area 0.5 – 0.55 × as long as maximum width of compound eye. Mandible two-toothed and largely black except sometimes for dark reddish-brown preapical zone. Apical margin of clypeus denticulate. Face and gena including ventral side covered with dense whitish pilosity, which is partly appressed on paraocular area and distinctly less dense on clypeal centre. First segment of labial palpus 1.15 – 1.2 × as long as second segment. Flagellum of antenna simple and consisting of regularly cylindrical segments, which are longer than wide and vary in colour from predominantly brownish to largely reddish (Fig. 17). Mesosoma: Parapsidal line long-linear. Punctation of scutum, scutellum and mesepisternum dense with interspaces rarely exceeding the diameter of half a puncture. Basal area of propodeum shagreened and basally longitudinally striate. Pilosity of mesosoma whitish. Tegula yellowish-brown to yellowish-red and sparsely punctured over its entire surface. Stigma and veins of fore wing predominantly dark brown. Apical margin of tibial spur of fore leg extended into long spine, which is longer than basally wide. Tibial spurs of hind leg yellowish-white, long, slender, largely straight and apically not or only very weakly curved. Metasoma: Punctation of tergal discs 2 – 4 medially rather fine and sparse with interspaces reaching the diameter of up to two to three punctures. Punctation of terga 5 – 6 denser with interspaces rarely exceeding the diameter of one to one and a half punctures. Marginal zone of terga 1 – 6 distinctly reddish-coloured (Fig. 18). Marginal zone of terga 1 – 5 with short white hair bands, which are not interrupted in fresh specimens (Fig. 12). Protruding median part of apical margin of tergum 6 crenulate and / or with shallow median emargination (Fig. 18). Tergum 6 laterally with distinct narrowly triangular tooth (Fig. 18). Apical margin of tergum 7 medially shallowly emarginate (Fig. 18), its lateral margin ventromedially with small angular projection. Apical margin of sterna 1 – 4 almost straight and beset with white pilosity, which is rather dense and moderately long on sterna 1 – 3 and distinctly shorter and sparser on sternum 4 (Fig. 19). Apical margin of sternum 5 very slightly rounded (rarely with very shallow median emargination) and almost hairless (Fig. 19). Marginal zone of sterna 2 – 5 reddish coloured and with fine and dense punctation (Fig. 19). Punctation of disc of sternum 5 very sparse with interspaces reaching the diameter of several punctures (Fig. 19), distinctly contrasting with the denser punctation of the preceding sternal discs, where the interspaces reach the diameter of up to two (sternum 2) to four (sternum 4) punctures. Sternal discs 2 – 5 with very low to indiscernible transversal swellings (Fig. 19). Sternum 6 at base with pair of large translucent flaps (Fig. 19). Lateral lobes of bilobed membraneous appendage of sternum 6 densely haired, roundish to slightly oval and separated from each other apically by a shallow emargination and basally by a polished and hairless zone (Fig. 19). Gonoforceps slightly bent inwards and downwards in its apical third.	en	Müller, Andreas, Shebl, Mohamed A., Alqarni, Abdulaziz S. (2026): Three new osmiine bee species from the extreme desert of Saudi Arabia with specialized pollen-collecting behaviours (Megachilidae, Osmiini). Zootaxa 5782 (2): 330-346, DOI: 10.11646/zootaxa.5782.2.5, URL: https://doi.org/10.11646/zootaxa.5782.2.5
DE79FF2B7D15FFCA5C8790F3FE418FE3.taxon	distribution	Distribution. Arabian Desert from Israel (Arava valley northwards to the Dead Sea) to central Saudi Arabia (Hail and Riyadh provinces) (Fig. 20).	en	Müller, Andreas, Shebl, Mohamed A., Alqarni, Abdulaziz S. (2026): Three new osmiine bee species from the extreme desert of Saudi Arabia with specialized pollen-collecting behaviours (Megachilidae, Osmiini). Zootaxa 5782 (2): 330-346, DOI: 10.11646/zootaxa.5782.2.5, URL: https://doi.org/10.11646/zootaxa.5782.2.5
DE79FF2B7D15FFCA5C8790F3FE418FE3.taxon	etymology	Etymology. The species epithet refers to the boraginaceous genus Trichodesma, which is the most important pollen host of H. trichodesmae.	en	Müller, Andreas, Shebl, Mohamed A., Alqarni, Abdulaziz S. (2026): Three new osmiine bee species from the extreme desert of Saudi Arabia with specialized pollen-collecting behaviours (Megachilidae, Osmiini). Zootaxa 5782 (2): 330-346, DOI: 10.11646/zootaxa.5782.2.5, URL: https://doi.org/10.11646/zootaxa.5782.2.5
DE79FF2B7D18FFC15C87957BFE788F61.taxon	materials_examined	Holotype. SAUDI ARABIA: Riyadh: Ulya, 100 km NW Riyadh, 25.281 ° N / 46.021 ° E, 9.3.2024, ♀ (leg. M. Halada). Deposited in the Entomological Collection of ETH Zurich. Paratype. JORDAN: Zarqa: Azraq, 24.4.1996, 1 ♂ (leg. M. Halada). SAUDI ARABIA: Riyadh: Riyadh, Derab, Agricultural Research Station, 24.488222 ° N / 46.619850 ° E, 10.3.2011, 1 ♂ (leg. M. A. Hannan), 12.02.15, 1 ♀, 1 ♂ (leg. M. Shebl); Riyadh, Al Amariah, Majra Al-Gasim, 24.712611 ° N / 46.722447 ° E, 13.3.2012, 1 ♀ (leg. M. A. Hannan), 20.3.2025, 1 ♀ (leg. I. Naser); S of Riyadh, 24.425 ° N / 46.653 ° E, 6.3.2024, 1 ♀, 1 ♂ (leg. M. Halada); 40 km NE Mulham, 25.469 ° N / 46.587 ° E, 7.3.2024, 1 ♂ (leg. M. Halada); Ulya, 100 km NW Riyadh, 25.281 ° N / 46.021 ° E, 9.3.2024, 2 ♀, 3 ♂ (leg. M. Halada); Al Hair SE Riyadh, 24.392 ° N / 46.793 ° E, 520 m, 24.3.2025, 2 ♂ (leg. M. Halada). Deposited in the Entomological Collection of ETH Zurich.	en	Müller, Andreas, Shebl, Mohamed A., Alqarni, Abdulaziz S. (2026): Three new osmiine bee species from the extreme desert of Saudi Arabia with specialized pollen-collecting behaviours (Megachilidae, Osmiini). Zootaxa 5782 (2): 330-346, DOI: 10.11646/zootaxa.5782.2.5, URL: https://doi.org/10.11646/zootaxa.5782.2.5
DE79FF2B7D18FFC15C87957BFE788F61.taxon	diagnosis	Diagnosis. Hoplitis trisinuata belongs to the subgenus Platosmia, which is characterized by the clypeus that considerably overhangs the base of the labrum in the female and by the bifid to triangular tergum 7 that lacks a dorsal pit in the male. Among the species of H. (Platosmia), the 5.5 – 6.5 mm long female of H. trisinuata (Fig. 21) is unequivocally diagnosable by the following two characters: i) tarsal segments 2 – 4 of the fore leg with numerous apically curved bristles (Fig. 24, 37) and ii) median part of the apical margin of the clypeus medially weakly convex and laterally with a short, narrow and rounded process on each side, giving the clypeal margin a triple-arched shape (Fig. 23). Additional characters of the female are iii) the unpunctured, polished, narrow and partly weakly impressed median zone of the clypeus (Fig. 23), iv) the relatively long first segment of the labial palpus being almost as long as the antennal scapus, v) the truncate to slightly rounded apical margin of the tibial spur of the fore leg (Fig. 25), iv) the long, slender and almost straight inner tibial spur of the hind leg, and vi) the distinctly reddish-coloured marginal zone of the terga 1 – 5. The 5 – 6 mm long male of H. trisinuata (Fig. 22) differs from all other H. (Platosmia) species by the combination of the following four characters: i) apical margin of tergum 7 slightly to moderately emarginate (Fig. 26), ii) apical margin of sternum 6 with dense whitish to yellowish hair band (Fig. 28), iii) sternum 6 medioapically very weakly impressed and very slightly projecting beyond the otherwise almost straight sternal margin (Fig. 28), and iv) apical margin of sternum 3 with deep emargination, which is about half to three quarters as deep as wide and not covered with dense whitish pilosity (Fig. 27). Additional characters of the male are v) the relatively long first segment of the labial palpus being almost as long as the antennal scapus, vi) the truncate to slightly rounded apical margin of the tibial spur of the fore leg, and vii) the distinctly reddish-coloured marginal zone of the terga 1 – 6 (Fig. 26).	en	Müller, Andreas, Shebl, Mohamed A., Alqarni, Abdulaziz S. (2026): Three new osmiine bee species from the extreme desert of Saudi Arabia with specialized pollen-collecting behaviours (Megachilidae, Osmiini). Zootaxa 5782 (2): 330-346, DOI: 10.11646/zootaxa.5782.2.5, URL: https://doi.org/10.11646/zootaxa.5782.2.5
DE79FF2B7D18FFC15C87957BFE788F61.taxon	description	Description. FEMALE (Fig. 21): Body length 5.5 – 6.5 mm. Head: Head 0.9 – 0.95 × as long as wide. Distance between posterior margin of lateral ocellus and preoccipital margin 1.7 – 1.8 × as long as ocellar diameter. Maximum width of genal area 0.75 – 0.85 × as long as maximum width of compound eye. Clypeus weakly convex and medially with unpunctured, polished, narrow and partly weakly impressed longitudinal zone (Fig. 23). Median part of apical margin of clypeus medially weakly convex and laterally with a short, narrow and rounded process on each side, giving the clypeal margin a triple-arched shape (Fig. 23). Clypeus except for unpunctured longitudinal zone and unpunctured apical marginal zone densely punctured with interspaces rarely exceeding the diameter of half a puncture (Fig. 23). Punctation of supraclypeal area slightly finer and denser than that of clypeus (Fig. 23). Punctation of frons very dense with interspaces hardly reaching the diameter of half a puncture. Mandible three-toothed and largely black except for preapical zone, which is more or less dark reddish-brown. Paraocular area and sides of supraclypeal area densely covered with semierect to appressed white pilosity. Pilosity of frons white, sparse and semierect. Clypeus largely hairless except for its lateral sides, which are covered with rather long, sparse and semierect whitish pilosity (Fig. 23). First segment of labial palpus almost as long as scapus of antenna. Second segment of labial palpus 1.3 – 1.35 × as long as first segment. Anterior (and partly also posterior) side of antennal segments (4) 5 – 11 (12) more or less reddish-brown coloured. Antennal segment 3 1.15 – 1.2 × as long as wide and distinctly shorter than segment 4, which is about 0.75 × as long as wide. Mesosoma: Parapsidal line long-linear. Punctation of scutum and mesepisternum dense with interspaces rarely exceeding the diameter of one puncture, that of scutellum slightly sparser with interspaces reaching the diameter of up to one and a half, rarely two punctures. Basal area of propodeum polished except for narrow zone along metanotum, which is strongly shagreened and crossed by very fine longitudinal striae. Pilosity of mesosoma whitish. Tegula yellowish-red except for black inner margin and very sparsely punctured except for more densely punctured anterior half and inner margin. Stigma and veins of fore wing predominantly dark brown to black. Tarsal segments 2 – 4 of fore leg with numerous apically curved bristles (Fig. 24, 37). Apical margin of tibial spur of fore leg truncate to slightly rounded (Fig. 25). Inner tibial spur of hind leg long, slender and almost straight. Pilosity of inner surface of basitarsus of hind leg yellowish-white. Metasoma: Punctation of tergal discs 2 – 4 medially moderately dense with interspaces reaching the diameter of up to two or three punctures, that of marginal zones finer and denser. Punctation of terga 5 – 6 denser with interspaces rarely exceeding the diameter of one to one and a half punctures. Marginal zone of terga 1 – 5 distinctly reddish-coloured. Terga 1 – 5 with short white hair bands, which are not interrupted in fresh specimens (Fig. 21). Tergum 6 covered with sparse, appressed and whitish pilosity. Scopa whitish. MALE (Fig. 22): Body length 5 – 6 mm. Head: Head 0.85 – 0.9 × as long as wide. Distance between lateral ocellus and preoccipital margin 1.5 – 1.6 × as long as ocellar diameter. Maximum width of genal area 0.45 – 0.55 × as long as maximum width of compound eye. Mandible two-toothed and largely black except for dark reddish-brown preapical zone. Apical margin of clypeus denticulate. Face covered with very dense white pilosity, which is predominantly appressed except for semierect to erect pilosity on frons and around antennal sockets. Apical margin of clypeus with several tufts of short whitish hairs originating from below the clypeal margin. First segment of labial palpus almost as long as scapus of antenna. Second segment of labial palpus 1.3 – 1.4 × as long as first segment. Anterior side of flagellum of antenna brown to reddish-brown. Antennal segments 3 – 4 shorter than wide, segment 5 about as long as wide, segments 6 – 12 slightly longer than wide and segment 13 about 1.5 × as long as wide. Mesosoma: Parapsidal line long-linear. Punctation of scutum and scutellum moderately dense with interspaces reaching the diameter of up to one and a half to two punctures. Punctation of mesepisternum dense with interspaces rarely exceeding the diameter of half a puncture. Basal area of propodeum polished except for narrow zone along metanotum, which is strongly shagreened and crossed by very fine longitudinal striae. Pilosity of mesosoma whitish. Tegula yellowish-red except for black inner margin and very sparsely punctured except for more densely punctured anterior half and inner margin. Stigma and veins of fore wing predominantly brown to dark brown. Apical margin of tibial spur of fore leg truncate to slightly rounded. Tibial spurs of hind leg yellowish-white, long, slender, largely straight and apically only very weakly curved. Metasoma: Punctation of tergal discs medially rather fine and sparse with interspaces reaching the diameter of up to two or three and occasionally even more punctures, that of marginal zones finer and denser. Marginal zone of terga 1 – 6 distinctly reddish-coloured (Fig. 26). Marginal zone of terga 1 – 5 with short white hair bands, which are not interrupted in fresh specimens (Fig. 22). Apical margin of tergum 6 medially evenly rounded and laterally with short tooth (Fig. 26). Apical margin of tergum 7 slightly to moderately emarginate (Fig. 26). Apical margin of sternum 1 straight, of sternum 2 rounded except for very small median emargination and of sternum 3 with deep median emargination, which is about half to three quarters as deep as wide and not covered with dense whitish pilosity (Fig. 27). Marginal zone of sterna 1 – 3 beset with sparse white pilosity, which is very short on sternum 1 and moderately long on sterna 2 – 3. Sternum 4 medioapically with deep and densely haired emargination, which occupies two-fifths of horizontal sternal width (Fig. 27). Sternum 5 apically almost straight to slightly rounded, sparsely punctured and only inconspicuously haired (Fig. 27). Sternum 6 medioapically very weakly impressed and very slightly projecting beyond the otherwise almost straight sternal margin, its apical margin with dense whitish to yellowish hair band (Fig. 28). Genitalia as in Fig. 29.	en	Müller, Andreas, Shebl, Mohamed A., Alqarni, Abdulaziz S. (2026): Three new osmiine bee species from the extreme desert of Saudi Arabia with specialized pollen-collecting behaviours (Megachilidae, Osmiini). Zootaxa 5782 (2): 330-346, DOI: 10.11646/zootaxa.5782.2.5, URL: https://doi.org/10.11646/zootaxa.5782.2.5
DE79FF2B7D18FFC15C87957BFE788F61.taxon	distribution	Distribution. Arabian Desert from Jordan (Zarqa governorate) to central Saudi Arabia (Riyadh province) (Fig. 30).	en	Müller, Andreas, Shebl, Mohamed A., Alqarni, Abdulaziz S. (2026): Three new osmiine bee species from the extreme desert of Saudi Arabia with specialized pollen-collecting behaviours (Megachilidae, Osmiini). Zootaxa 5782 (2): 330-346, DOI: 10.11646/zootaxa.5782.2.5, URL: https://doi.org/10.11646/zootaxa.5782.2.5
DE79FF2B7D18FFC15C87957BFE788F61.taxon	etymology	Etymology. The species epithet refers to the triple-arched shape of the clypeal margin (lat. “ tri ” = three, lat. “ sinuatus ” = arched).	en	Müller, Andreas, Shebl, Mohamed A., Alqarni, Abdulaziz S. (2026): Three new osmiine bee species from the extreme desert of Saudi Arabia with specialized pollen-collecting behaviours (Megachilidae, Osmiini). Zootaxa 5782 (2): 330-346, DOI: 10.11646/zootaxa.5782.2.5, URL: https://doi.org/10.11646/zootaxa.5782.2.5
DE79FF2B7D18FFC15C87957BFE788F61.taxon	discussion	Note. The reexamination of the H. (Platosmia) male from Azraq in central eastern Jordan, which was assigned to Hoplitis gerofita (Warncke, 1990) by Müller (2015), proved to belong to H. trisinuata. Thus, the record of H. gerofita for Jordan is erroneous, the species is currently known only from Egypt and Israel.	en	Müller, Andreas, Shebl, Mohamed A., Alqarni, Abdulaziz S. (2026): Three new osmiine bee species from the extreme desert of Saudi Arabia with specialized pollen-collecting behaviours (Megachilidae, Osmiini). Zootaxa 5782 (2): 330-346, DOI: 10.11646/zootaxa.5782.2.5, URL: https://doi.org/10.11646/zootaxa.5782.2.5
DE79FF2B7D18FFC15C87957BFE788F61.taxon	biology_ecology	Biology of the new species Pollen hosts. The microscopical analysis of pollen contained in the metasomal scopa of collected females revealed that Hoplitis heliotropii and H. trisinuata are polylectic (Tab. 1). Both species collected pollen on the flowers of Heliotropium (Boraginaceae) and Brassicaceae. As only two pollen loads were available for H. heliotropii, the analysis of additional loads is needed to assess the importance of Heliotropium pollen in the species’ larval diet. In contrast, the high significance of Heliotropium as pollen host for H. trisinuata is clearly revealed by the finding that its pollen was recorded in all seven loads analysed, whereas Brassicaceae pollen occurred only in a single load. In the surroundings of Riyadh, both females and males of H. heliotropii and H. trisinuata were observed to visit the flowers of Heliotropium bacciferum Forssk. (Fig. 33), a common subshrub widely distributed in the Arabian desert (Migahid 1996). In contrast to Hoplitis heliotropii and H. trisinuata, H. trichodesmae turned out to be oligolectic restricting pollen collection to the Boraginaceae (Tab. 1). Based on the microscopical analysis of female pollen loads, Trichodesma is by far the main pollen host among the Boraginaceae. Its pollen was found in all 15 pollen loads analysed, whereas only three loads additionally contained small amounts of pollen of Echium, which suggests that pollen of Boraginaceae other than Trichodesma is occasionally also harvested. Field observations near Riyadh supported the results of the pollen analysis: both females and males of H. trichodesmae visited the flowers of Trichodesma africanum L. (Sm.) (Fig. 34, 35), which is a widespread annual or perennial plant in the Arabian desert (Migahid 1996). In Israel, T. africanum likewise served as a pollen host for H. trichodesmae, together with T. ehrenbergii Schweinf. (Dukas & Dafni 1990, as Hoplitis spec.; Sedivy et al. 2013 b, as Hoplitis spec. nov. 3). Pollen-collecting strategies. The females of Hoplitis heliotropii and H. trisinuata are equipped with specialized bristles on the proboscis and the fore legs, respectively. In H. heliotropii, these bristles cover the first and the second segment of the labial palpus and are apically curved (Fig. 4, 5, 36), whereas in H. trisinuata they occur on the fore tarsal segments 2 – 4 and are apically hooked (Fig. 24, 37). Given the hidden position of the anthers within the narrow corolla tube of Heliotropium and the use of Heliotropium as pollen source by both species, it is strongly suspected that these bristles serve to scrape pollen out of the flowers by moving the proboscis up and down in H. heliotropii and by alternately moving the two fore legs inside the corolla back and forth in H. trisinuata. This assumption is supported by the finding that pollen clumps from Heliotropium stuck to the specialized pilosity in both H. heliotropii and H. trisinuata (Fig. 36). Females of Hoplitis trichodesmae audibly vibrated the flowers of Trichodesma africanum to extract the pollen from inside the tightly appressed introrse anthers (Fig. 35). The same buzzing behaviour by H. trichodesmae was also observed in Israel, where the bees exploited T. africanum and T. ehrenbergii (Dukas & Dafni 1990, as Hoplitis spec.; Sedivy et al. 2013 b, as Hoplitis spec. nov. 3), indicating that vibratile pollen harvesting is a basic pollen-collecting strategy in this species. Nesting behaviour. No nests of the three newly described osmiine bee species were discovered. However, Hoplitis heliotropii and H. trichodesmae are expected to build their brood cells in surface irregularities or holes of stones and rocks, as the vast majority of the members of the H. adunca species group do (Sedivy et al. 2013 a). Given the absence or scarcity of woody structures in the desert habitats of these two species, it seems unlikely that they nest in insect burrows in dead wood, as is known from a few species of the H. adunca group (Aubert et al. 2024). Similarly, since the only two species of H. (Platosmia) for which information on the nesting biology is available have been found to build their nests in stone cavities (Warncke 1990; Müller 2015), it is suggested that H. trisinuata likewise nests in holes and fissures of rocks and stones. In fact, stony structures were plentiful in the habitats of all three species (Fig. 31, 32).	en	Müller, Andreas, Shebl, Mohamed A., Alqarni, Abdulaziz S. (2026): Three new osmiine bee species from the extreme desert of Saudi Arabia with specialized pollen-collecting behaviours (Megachilidae, Osmiini). Zootaxa 5782 (2): 330-346, DOI: 10.11646/zootaxa.5782.2.5, URL: https://doi.org/10.11646/zootaxa.5782.2.5
