Hylaeus (Hylaeus) kozlovi Dathe & Proshchalykin

Dathe, Holger H. & Proshchalykin, Maxim Yu., 2016, The genus Hylaeus Fabricius in Mongolia, an updated species inventory (Hymenoptera: Apoidea, Colletidae), Zootaxa 4121 (4), pp. 351-382 : 362-363

Hylaeus (Hylaeus) kozlovi Dathe & Proshchalykin , sp. n.

Figures 4 h, 5, 7, 9

Diagnosis. The new species, together with Hylaeus oblitus (Warncke) , H. przewalskyi Morawitz and the Usbek H. cinereus (Warncke) , is one of the smallest species in the greater area of Central Asia. It is extraordinarily similar to H. oblitus (Warncke) , but however differs in both sexes in the shorter and wider profile of its head ( Figs 5 –8). The head index HL:HW according to available measurements in H. kozlovi sp. n. is 0.94.–1.00 (♂) and 0.96–0.99 (♀), with a mean of 0.97 in both; for H. oblitus ♂ indices of 1.01–1.06 (mean 1.04) were obtained, for the ♀ 1.04–1.08 (mean 1.06); the ranges do not overlap each other. Also the male terminalia appear to be subtly different. In H. oblitus the outline of the genital capsule is more stretched and its distal part less angular; the apical lobe of sternum 8 is more deeply emarginate and sternum 7 has 11 comb teeth instead of 10 as in H. kozlovi sp. n. ( Figs 9 , 10). However, this is based on the examination of only a few specimens.

Description. Male. Measurements (n=13): total length 3.6–4.1 (3.84) mm, wing length 2.5–3.0 (2.77) mm.

Head proportions HL:HW 0.97, UHW:LHW 1.97, outline rounded trapezoidal ( Fig. 5 a). Scapi slender conoid, SL:SW 2.34; black with wide white vertical stripe; flagella of medium length, apically wider than scapi; totally yellow, spherical basal segments with white fleck. Mask complete, white, side patches expanded to lower margin of scapi bases, transversely truncated above, mostly connected straight to orbits. Supraclypeal area wide below, broader than distance from clypeus basis to the orbits; surface longitudinally striate, nearly without punctation, transition to the frons gentle. Clypeus CL:CW 1.59, lower part arched, anterior margin black, with erect bristles; surface longitudinally wrinkled with scattered shallow punctation, silkily shining. Foveae faciales are short but distinct. Frons and vertex smooth and shiny, with very fine shagreen only; scapus area without punctation, upper frons and vertex with dense, moderate punctation; vertex with sparse pilosity. Frontal midline consisting of two fine ridges. Genae normal, longitudinally striate; occiput rounded; malae narrow. Labrum and bifid mandibles dark, black and brown.

Mesosoma short, rounded ( Figs 5 b, c); pilosity sparse, thorax and propodeum with scattered white hairs. Coloration black, pronotum laterally with two white stripes, sometimes small or absent, calli and tegulae with white spot. Pronotum narrow, only laterally somewhat expanded, anterior margin in the middle narrow, dorsolateral angles sloping. Mesonotum and scutellum finely shagreen, shiny, with irregularly sparse, moderate to strong punctation; metanotum matt, with rugose punctation; mesopleura similar to mesonotum, but with punctation still more scattered; anterior margin rounded. Legs black, white are femoral tips, anterior surface of foretibiae, base and tip of other tibiae and whole tarsi; wings hyaline, venation yellow, stigma brown. Propodeum ( Fig. 5 d) edged, with coarse wrinkled surface, slightly shiny; medial area delimited from other areal parts by a series of meshes; terminal area edged around, propodeal furrow wide.

Metasoma narrow spindle-shaped, coloration black. T1 ( Fig. 5 d) smooth and shining, punctation sparse, moderate; surface with short white hairs; T2 and following terga finely shagreen, with somewhat finer and denser punctation. Terminalia ( Figs 9 a–c): genital capsule oval, with penis valves longer than gonoforcipes, the contour of gonoforcipes in dorsal view at their distal end with a slight bend; S8 with apical lobus flatly emarginated; S7 with slightly flattened pectinate processes, proximal lobes narrowly expanded.

Female. Measurements (n=12): total length 3.6–4.4 (4.11) mm, wing length 2.9–3.3 (3.11) mm.

Head proportions HL:HW 0.97, UHW:LHW 1.64, outline trapezoidal ( Fig. 7 a). Scapi black, usually with triangular white patch at the top; flagella short, yellow, brownish above, basal segments with dark rings. Face with long-oval to rectangular spots, often filling paraocular area up to scapus bases. Supraclypeal area short, with longitudinal striation; with a gradual transition to the frons but indistinctly separated from clypeus. Clypeus CL:CW 1.54, longitudinally wrinkled striate with scattered shallow punctation, matt. Foveae faciales long, reaching upper eye border. Frons and vertex finely shagreen, smooth and shiny, with close, fine punctation. Frontal midline relatively clear. Genae longitudinally striate, satin glossy; occiput narrow, rounded; malae narrow. Labrum black, bifid mandibles brown.

Mesosoma ( Figs 7 b, c) long-oval, rounded, somewhat depressed; pilosity inconspicuous, sparse, short and lying flat. Coloration black, pronotum laterally with two white stripes, tegulae and calli with a white spot each. Pronotum narrow, anterior margin edged in the middle, dorsolateral angles shallow. Mesonotum and scutellum shagreen, silkily shiny, punctation dense, moderate; metanotum shagreen wrinkled, matt; mesopleura with fine shagreen, silkily shiny, with shallow sparse, fine punctation, anterior margin rounded. Legs black, with white femoral tips, white are also anterior surface of foretibiae, base and tip of other tibiae and tarsi; wings hyaline, venation yellow, stigma brown. Propodeum ( Fig. 7 d) edged, sculpture coarse mesh-wrinkled, shining; medial area marked by a mesh row, which merges in the middle into a broad terminal furrow; its upper triangular part with fine shagreen; terminal area around with very fine margin.

Metasoma compact spindle-shaped, coloration black. T1 ( Fig. 7 d) smooth and shiny, with punctation close to sparse, fine, without lateral fringes; following terga finely shagreen, with shallow punctation, sparsely hairy, margin of depressions translucent; terga without fringes; fringe of last sternum yellowish.

Type material: 20 ♂, 10 ♀

Holotype: ♂ Mongolia. Khovd Aimag: 20 km S Altai, Elkhon, 22.–23.VI.1980, MK ( ZISP).

Paratypes: Mongolia. Khovd Aimag: 1 ♂, 5 ♀, 20 km S Altai, Elkhon, 22.–23.VI.1980; 13 ♂, 20 km SE Altai, Elkhon, 28.VII.1970; 1 ♂, 2 ♀, 50 km SSW Uench, Utyn-Mod, 27.VI.1980, all MK ( ZISP); 1 ♂, 1 ♀, 12 km SW Altai, Bodonchin-Gol, 22.VII.1970, IK ( ZISP). Zavkhan Aimag: 1 ♀, Khangai Ridge (near Ulyasutai), 1877, G.N. Potanin ( ZISP); Bayan-Khongor Aimag: 1 ♂, Toroin-Bulak, 13 km E Tsagan-Bulak, 16.VIII.1969, KA ( ZISP); 1 ♂, 1 ♀, Burkhant-Bulak, 60 km SSW Shine-Dzhinst, EN ( ZISP). Uvs Aimag: 1 ♂, 50 km ESE Ulangom, Togtokhyn-Shil Mt., 07.VIII.1970, MK ( ZISP).

Etymology. The new species is dedicated to Michail Alexeevich Kozlov (1936–2006), an entomological supervisor and frequent participant in the Soviet-Mongolian Complex Biological Expeditions 1967–1982. He collected numerous new insects in Mongolia, including the present new species.

Discussion. Previously, two very small Hylaeus species were known from the territory of Mongolia. One of them, H. przewalskyi Morawitz , is conspicuous because of its rich yellow coloration and is thereby easily recognised; the other, H. oblitus (Warncke) , is black and inconspicuous. The species was originally described as H. pusillus Morawitz (♂) und H. albitarsis Morawitz (♀), although even the author himself ( Morawitz 1890: 380) discussed a possible synonymy. Dathe (1986a: 285) had also already pointed this out, without being able to reach a taxonomic decision. He also illustrated H. oblitus (Warncke) (p. 284, Figs 42 and 43, as " Hylaeus fuliginosus (Warncke) ").

Based on the specimens before us, including historical material, it is now possible to argue strongly for the separation of a further small species, H. kozlovi sp. n. This is extraordinarily similar to H. oblitus in habitus, coloration and sculpture: the females even both have white tarsi. The differences are subtle, only being clearer in the proportions of the facial structures. Both species seem, where they occur, to appear in large numbers, so that usually series of specimens are available that in direct comparison can be readily assigned to the correct taxon.

At one of the collection localities, Elkhon 25 km S Altai, Kozlov found on 22.–23.VI. 1980 both species directly side by side. It could easily be suspected that morphs of the same species are involved, as for example occurs in halictids. However, social structures are unknown in the genus Hylaeus . Only in a single case, the Brazilian Hylaeus (Hylaeopsis) tricolor (Schrottky) , is "facultative quasisociality" suspected ( Sakagami & Zucchi, 1978). The lack of observed overlap in morphological characters also speaks against the two 'forms' being conspecific. Some characters, such as the white spot on the scape of females of H. kozlovi sp. n., are confined to this 'form', so that despite their great similarity, we assume that two separate species are involved. In Figures 5 –10, main features of the species are juxtaposed.

Figures

FIGURE 4. Distribution of Hylaeus species in Mongolia: a — H. sibiricus, H. pirus; b — H. pfankuchi, H. gracilicornis; c — H. przewalskyi, H. paulus; d — H. tsingtauensis, H. nimbatus; e — H. stubbei, H. valinis; f — H. confusus, H. ulanus; g — H. dorni, H. montivagus; h — H. kozlovi sp. n.; i — H. mongolicus, H. potanini; j — H. mellon sp. n.

FIGURE 5. Hylaeus (Hylaeus) kozlovi sp. n., holotypus male: a — face, b — mesonotum, c — mesopleuron, d — propodeum and basal terga. Scale bar 1 mm. FIGURE 6. Hylaeus (Hylaeus) oblitus (Warncke), male: a — face, b — mesonotum, c — mesopleuron, d — propodeum and basal terga.

FIGURE 7. Hylaeus (Hylaeus) kozlovi sp. n., paratype female: a— face, b — mesonotum, c— mesopleuron, d — propodeum and basal terga. Scale bar 1 mm. FIGURE 8. Hylaeus (Hylaeus) oblitus (Warncke), female: a — face, b — mesonotum, c — mesopleuron, d — propodeum and basal terga.

FIGURE 9. Hylaeus (Hylaeus) kozlovi sp. n., holotypus male: a — sternum 7, b — sternum 8, c — genital capsule. Scale bar 0.2 mm. FIGURE 10. Hylaeus (Hylaeus) oblitus (Warncke), male: a — sternum 7, b — sternum 8, c — genital capsule.