Hofferia

Müller, Andreas & Trunz, Vincent, 2014, Palaearctic osmiine bees of the genera Hofferia and Stenoheriades (Megachilidae, Osmiini): biology, taxonomy and key to species, Zootaxa 3765 (2), pp. 175-186 : 176-177

Morphological diagnosis of Hofferia and Stenoheriades

Both Hofferia and Stenoheriades strongly resemble species of the genus Chelostoma Latreille due to their slender and elongate body form. The following key, which is tailored to the Palaearctic representatives of the Osmiini , delimits Hofferia and Stenoheriades from Chelostoma and the other Palaearctic osmiine bee genera.

1 Segment 3 of the labial palpus continues the axis of segment 2, whereas segment 4 projects laterally.......................................................................................... Chelostoma group: genus Chelostoma Chelostoma Latreille contains 45 described Palaearctic species. Body length 4–15mm. Body slender and elongate. Females: Mandible usually fringed with long hairs along upper margin. Labrum without tuft of long erect hairs. Clypeus without sharp preapical ridge. Sternum 6 apically without distinct spine-like projection. Males: Tergum 6 without preapical ridge. Tergum 7 with large basal depression or pit, its apical margin bidentate, tripartite, medially incised, truncated or rounded. Sternum 1 not prolonged. Sternum 2 with median projection of different shape. Posterior margin of sternum 5 usually with comb of bristles.

1* Both segments 3 and 4 of the labial palpus project laterally..................................................... 2

2 Basal zone of propodeum horizontal to faintly slanting, short, sharply ridged and with distinct transverse carina along its posterior margin........................................................................................... 3

2* Basal zone of propodeum of different inclination, length or structure, but usually not distinctly carinated posteriorly; if carinated, declivous part of tergum 1 not separated from horizontal part by raised carina................................ 5

3 Declivous part of tergum 1 separated from horizontal part by indistinct rounded ridge. Proboscis long, reaching beyond coxa of fore leg when folded together; total length of first and second segments of labial palpus almost as long as maximal length of mesosoma. Body length usually longer than 7.5mm ................................. Heriades group: genus Hofferia Hofferia Tkalců contains 2 described Palaearctic species. Body length 7.5–10.5mm. Body slender and elongate, Chelostoma - like. Females: Head very robust, maximal width of genal area distinctly wider than compound eye. Mandible long and slender, not fringed with long hairs along upper margin ( Figs. 4, 5 ). Labrum without tuft of long erect hairs. Apical half of clypeus bent at right angles and separated from basal half by sharp preapical ridge ( Figs. 4, 5 ). Sternum 6 medioapically with distinct spinelike projection. Males: Tergum 6 with preapical transverse ridge, which is irregularly denticulate. Tergum 7 without large basal depression or pit, its apical margin truncated and projecting medially. Sternum 1 prolonged, basally bulging and apically with flat appendix of rectangular to quadrate shape ( Figs. 6, 7 ). Sternum 2 without median projection. Sternum 5 covered with transversally oriented yellowish hairs; its apical margin without comb of bristles, laterally with tuft of yellowish-red hairs.

3* Declivous part of tergum 1 distinctly separated from horizontal part by sharp and raised carina. Proboscis short, not reaching coxa of fore leg when folded together; total length of first and second segments of labial palpus distinctly shorter than maximal length of mesosoma. Body length not exceeding 8mm ......................................................... 4

4 Females: Clypeus medioapically with short and narrowly rectangular projection ( Fig. 10 ) or more or less semicircular impression ( Figs. 13, 14 ); if apical margin of clypeus is straight, interantennal area with two raised carinae ( Fig. 8 ). Males: Tergum 6 with preapical transverse ridge, which is denticulate or has two median teeth ( Figs. 9 , 15 ). Tergum 7 strongly sclerotized, not hidden by tergum 6 and with two apical teeth ( Figs. 9 , 15 )...................... Heriades group: genus Stenoheriades Stenoheriades Tkalců contains 5 described Palaearctic species. Body length 5–8mm. Body slender and elongate, Chelostoma - like. Axilla never spined. Females: Labrum with preapical tuft of long erect hairs. Mandible basally strongly swollen in one species ( Fig. 11 ). Males: Metasoma moderately curved. Tergum 6 with distinct lateral flaps. Sternum 1 never prolonged. Last antennal segment never flattened or broadened.

4* Females: Apical margin of clypeus more or less straight or shallowly emarginated along its whole width, with or without small tooth-like projections. Interantennal area without raised carinae. Males: Tergum 6 without preapical transverse ridge (except for Heriades (Rhopaloheriades) clavicornis ). Tergum 7 weakly sclerotized and completely hidden by large tergum 6................................................................................. Heriades group: genus Heriades Heriades Spinola contains 23 described Palaearctic species. Body length 4–8mm. Body moderately slender to moderately robust. Axilla spined in some species. Females: Labrum with preapical tuft of long erect hairs. Mandible basally never strongly swollen. Males: Metasoma strongly curved so that at most two sterna are exposed and apex of tergum 6 nearly contacts sternum 1 or 2. Tergum 6 without or with indistinct lateral flaps. Sternum 1 distinctly prolonged in one species. Last antennal segment flattened and broadened in one species.

5 Pronotal lobe with several minute transverse carinulae on its surface. Females: Labrum with preapical tuft of long erect hairs.

Males: Tergum 7 weakly sclerotized and completely hidden by large tergum 6.......... Heriades group: genus Protosmia Protosmia Ducke contains 22 described Palaearctic species. Body length 3.5–9mm. Body slender and elongate, Chelostoma - like, to rather robust. Females: Metasoma red-coloured in some species. Males: Sternum 1 prolonged, bulged or with distinct projection. Tergum 6 with lateral flaps. In some species, antenna modified and gena ventrolaterally with longitudinal groove.

5* Pronotal lobe usually without minute transverse carinulae on its surface. Females: Labrum without preapical tuft of long erect hairs. Males: Tergum 7 strongly sclerotized and not hidden by large tergum 6 (except for Osmia iberica ), albeit sometimes small................................................. Osmia group: genera Haetosmia , Hoplitis , Osmia , Wainia The genera Haetosmia Popov , Hoplitis Klug , Osmia Panzer and Wainia Tkalců contain about 500 described Palaearctic species. Body length 4–18mm. Very diverse in body shape, body colour and morphology.

Biology of Hofferia and Stenoheriades

All species of Hofferia and Stenoheriades have a strong affinity to Asteraceae as pollen hosts (see species accounts). Both Hofferia mauritanica (Lucas) and H. schmiedeknechti (Schletterer) are oligolectic on the subfamily Carduoideae . The only three pollen loads of Stenoheriades maroccana (Benoist) available so far contained pollen of the subfamily Cichorioideae , whereas the four other Palaearctic Stenoheriades species are probably all strictly specialized on the subfamily Asteroideae . Interestingly, all but one pollen loads of the three closely related species Stenoheriades asiatica (Friese) , S. coelostoma (Benoist) and S. levantica spec. nov. (n = 69) only contained pollen grains of the Anthemis type, whereas the pollen loads of S. eingeddica Griswold (n = 10) consisted exclusively of pollen grains of the Aster type. This finding suggests that these Stenoheriades species might possibly restrict pollen harvesting to certain taxa within the Asteroideae .

Hofferia schmiedeknechti nests in beetle burrows in dead wood ( Figs. 1–3 ; Tkalců, 1984), whereas the nesting biology of H. mauritanica is unknown. Several specimens of Stenoheriades maroccana and S. eingeddica were observed flying around dead wood ( Benoist, 1928b; C. Praz and C. Sedivy, personal communication), indicating that insect burrows in dead wood are probably used by Stenoheriades species as nesting sites as well. The slender and elongate body of both Hofferia and Stenoheriades is likely an adaptation for nesting in such narrow linear cavities. The discovery of nests of H. schmiedeknechti in Israel in spring 2013 by V. Trunz and D. Bénon revealed for the first time that this species constructs both cell walls and nest plug with resin, which is partly mixed with small pebbles ( Fig. 3 ). The nest building material of Stenoheriades species is still unknown. However, since all other genera of the Heriades group whose nesting behaviour is known use resin for nest construction ( Müller, 2013), resin is probably also used by the Stenoheriades species to build their brood cells.

In most parts of their Palaearctic distribution area, species of Hofferia and Stenoheriades do not emerge before mid-May and are mainly active from end of May to July except for S. eingeddica , which flies in April ( Israel) or October ( Oman, Yemen), and S. levantica , which is active from mid-March to end of May.

Figures

FIGURE 4 – 9. 4: Hofferia mauritanica, head of female. 5: Hofferia schmiedeknechti, head of female. 6: Hofferia mauritanica, sternum 1 of male. 7: Hofferia schmiedeknechti, sternum 1 of male. 8: Stenoheriades eingeddica, head of female. 9: Stenoheriades eingeddica, terga 5 – 7 of male.

FIGURE 10 – 15. 10: Stenoheriades maroccana, head of female. 11: Stenoheriades coelostoma, mandibles of female. 12: Stenoheriades levantica, mandibles of female. 13: Stenoheriades asiatica, clypeus and labral base of female. 14: Stenoheriades levantica, clypeus and labral base of female. Figure 15: Stenoheriades levantica, terga 5 – 7 of male.

FIGURE 1 – 3. 1: Nesting site of Hofferia schmiedeknechti on the Golan Heights in northeastern Israel, near Lehavot HaBashan; several females nested in trunk and branches of this dead Cupressus tree (Photo D. Bénon). 2: Female of Hofferia schmiedeknechti entering her nest in a beetle burrow in a dead Cupressus tree (Photo D. Bénon). 3: Opened nest of Hofferia schmiedeknechti with three linearly arranged brood cells; the nest is plugged with dark plant resin of unknown origin mixed with small pebbles; the cell walls also consist of resin.