Hylaeus garrulus (Warncke, 1981)

Divelec, Romain Le & Michez, Denis, 2025, Taxonomic revision of the garrulus species group in the bee genus Hylaeus Fabricius, 1793 (Hymenoptera: Apoidea, Colletidae), Zootaxa 5642 (2), pp. 127-146 : 129-135

publication ID	https://doi.org/10.11646/zootaxa.5642.2.2
publication LSID	lsid:zoobank.org:pub:62EAC552-954F-4E0D-8373-E5D3AAD2C970
DOI	https://doi.org/10.5281/zenodo.15585738
persistent identifier	https://treatment.plazi.org/id/C538E11A-FFAF-FFE3-FF04-F8DDFA723B1D
treatment provided by	Plazi
scientific name	Hylaeus garrulus
status

Treatment

Diagnosis of the garrulus View in CoL species group

The subgeneric classification of the genus Hylaeus has yet to be fully resolved, and some problems persist even within the European fauna, particularly in the classification of some species and the morphological concepts of the subgenera (Le Divelec, unpublished). Clarifying this classification is beyond the scope of this work and we can only suggest following the latest key to the Palearctic subgenera provided in Michener (2007). Although the identification of the males should be unambiguous thanks to the genitalia, there is a high risk of confusion in the females, more particularly between those of the garrulus group (subgenus Prosopis ) and those of the nivalis group (subgenus Hylaeus ). The latter group, as described in Dathe (2000), is artificial and it is necessary for it to be redefined in a separate work (Le Divelec, unpublished). Females of both groups share important diagnostic characteristics: a rounded propodeum without transverse or oblique carina, a T1 with apical fringes, light hairs on the last metasomal segment. As a result, some of the specimens of the garrulus group examined were previously confused with members of the nivalis group. The garrulus group can be distinguished from the nivalis group by the largely reticulate and strigate basal triangle (basal triangle with weak longitudinal ridges basally in the nivalis group, most of its surface only with tesselate tegument), the comparatively narrower scapus, i.e. as large as pedicel and narrower than median flagellomeres (larger than pedicel and as large as median flagellomeres in the nivalis group), the comparatively denser and deeper punctation on mesepisternum, and the distinct punctation on the hypoepimeral area (this area is tesselate without or with a few indistinct punctures in the nivalis group).

The Iberian garrulus species group can be recognized from other Prosopis by a distinctive combination of characters, somewhat intermediate between the gibbus and the variegatus species groups. Another species of Prosopis , H. gazagnairei (Vachal, 1891) also exhibits such an intermediate morphology, with an external morphology very similar to the species of the garrulus species group, more particularly in the males (see table 2). Due to those numerous similarities, members of the garrulus species group have been regularly misidentified as H. gazagnairei . As a matter of fact, the only published European record of H. gazagnairei , from Cartagena in Spain (Ornosa & Ortiz-Sánchez 2004), is based on a specimen housed at MNCN. The specimen was studied for this work, and it turned out to be H. teruelus . Therefore, it seems noteworthy to detail the main differences between H. gazagnairei and the members of the H. garrulus group, additionally to the differences with the two other main groups, the gibbus and the variegatus groups ( Tables 1–2 View TABLE 1 View TABLE 2 ).

The females of the garrulus species group are very similar to those of the gibbus group. They can be immediately recognised by the minute and indistinct punctation on the mesosternum which is conspicuously finer than that of mesepisternum, merged within the densely tesselate sculpture of the tegument. In the West Mediterranean area, other Prosopis species have a distinct punctation with small to large punctures on the mesosternum. The facial structure in the males of the garrulus group is reminiscent of the variegatus group ( Fig. 3G View FIGURE 3 ), with a trapezoidal and moderately dilated scape (0.8× as wide as long) and a crescent-shaped depression extending between the eyes, over the apex of the supraclypeal area and the base of the clypeus ( Figs 6A, 6F, 6K View FIGURE 6 ). As said previously, their general body is also very similar to that of H. gazagnairei . Males of the garrulus group can be recognized by the unique morphological features of their genital capsule, and more particularly by the structure of their penis valve. The inner surface of the penis valve is uniformly flat, its dorsal surface homogeneously oblique across all its length in cross section ( Figs 6D, 6I, 6N View FIGURE 6 ); in other groups, the dorsal surface is flattened and features a distinct inner angle due to the upper sclerotized part being swollen either along its entire length ( Figs 4C, 4M View FIGURE 4 ) or at least basally, as seen in the gibbus group ( Fig. 4H View FIGURE 4 ). The outer surface of the penis valve features a sharply elevated, straight longitudinal carina extending from the basal apodeme (valvura) to the apex of the penis valve ( Figs 6E, 6J, 6O View FIGURE 6 ). Above this carina, the cuticle is deeply concave, whereas in other groups, it is nearly flat. Below the carina, the cuticle is swollen, forming a deep and large invaginated opening just above the ventral subapical lobe. In contrast, other groups either lack this carina or have it reduced to a basal ridge, with the cuticle below it remaining flat and displaying only a shallow invagination above the ventral subapical lobe (see Figs 4E, 4J, 4O View FIGURE 4 ). In the garrulus group, the ventral subapical lobe is produced apically, far beyond the level of the ventral sinus, in a long and narrow free membranous lobe separated by a long sulcus from the ventral margin of the penis valve ( Figs 6E, 6J, 6O View FIGURE 6 ). In other groups, the subapical lobe is sclerotized, without membranous lobe, and entirely fused with the ventral margin of the penis valve ( Figs 4E, 4J, 4O View FIGURE 4 ). Additionally, to this unique penis valve, it is worth mentioning that the gonoforceps in the garrulus group are conspicuously arcuate or angulate apically and with a basal depression ( Fig. 6D, 6I, 6N View FIGURE 6 ); the volsella has a short digitus, flat in lateral view ( Fig. 8H View FIGURE 8 ). In other groups, the gonoforceps are straight to slightly curved inwards with a basal depression ( Figs 4C, 4H, 4M View FIGURE 4 ); and the volsella has a long digitus ( Figs 4D, 4I, 4N View FIGURE 4 ), large in lateral view.

To give more context to the information in tables 1 and 2, a simplified key to identify the main species groups and all the other species of the Prosopis subgenus that are not associated to them is here provided for Europe and Maghreb.

Female

1 – Last metasomal segment with dark hairs.................................................................. 2

– Last metasomal segment with light hairs.................................................................. 4

2 – Propodeum entirely carinate (i.e. with sharp oblique and transverse carinas). T1 smooth and impunctate. Mesepisternum matt with contiguous and coarse but superficial punctures..................................... H. trinotatus (Pérez, 1895)

– Propodeum not carinate (i.e. without conspicuous oblique and transverse carinas).T1 punctate and shagreened. Mesepisternum with different sculpture, punctures either finer or deeper....................................................... 3

3 – Facial fovea long (as long as distance between antennal socket and anterior ocellus) and curved inward, conspicuously divergent from inner orbit (lower end separated from it by 2–3 lines of punctures). Malar area reduced, indistinct. Basal triangle areolate-rugose ( Fig. 2A View FIGURE 2 ). T1 tesselate, entirely and uniformly punctate with small and dense to close punctures ( Fig. 2C View FIGURE 2 ). Disc of following terga matt, tesselate, with dense to close small punctures. Tibiae and tarsi usually entirely red............................................................................................ H. gazagnairei (Vachal, 1891)

– Facial fovea short (much shorter than distance between antennal socket and anterior ocellus) and straight, aligned along the entire length of inner orbit. Malar area longer, i.e. distinct. Basal triangle longitudinally ridged ( Fig. 2D View FIGURE 2 ). T1 with transverse shagreen, with scattered minute to fine punctures, punctation denser and coarser apically and laterally ( Fig. 2F View FIGURE 2 ). Disc of following terga silky shiny, with minute to fine scarce punctation. Tibiae and tarsi almost entirely black, tibiae with basal yellow spot................................................................................ gibbus species group

4 – Basal triangle matt, very finely alveolate laterally and apically over most of its surface, rugose only basomedially. Gena larger than eye in lateral view. Vertex gibbous, with distance beyond posterior ocellus of at least one posterior ocellus diameter before declivity. Mesepisternum with close to sparse punctures of two conspicuously different size, i.e coarse and small........................................................................................... H. duckei (Alfken, 1904)

– Basal triangle not alveolate, rugose to coarsely areolate over all its horizontal part. Gena shorter than eye in lateral view. Vertex immediately declivous beyond posterior ocellus. Mesepisternum with different sculpture, punctation fine or coarse but without two conspicuously different size of punctures......................................................... 5

5 – Facial fovea long and extended onto vertex, reaching center of posterior ocellus. Crosspoint of episternal sulcus and omaulus with very deep pit anteriorly bordered by conspicuous carina.............................. H. signatus (Panzer, 1798)

– Facial fovea shorter, reaching at most the anterior margin of posterior ocellus. Crosspoint of episternal sulcus and omaulus without deep pit or conspicuous carina..................................................................... 6

6 – Mesosternum rugulose with medium to large punctures. Basal triangle deeply rugose-areolate, with conspicuous transverse carina ( Fig. 2G View FIGURE 2 ). Propodeum sharply angular in lateral view. Inner hind tibial spur with long and sparse spine ( Fig. 2H View FIGURE 2 ). Axilla usually yellow. Base of metasoma usually red ( Fig. 2I View FIGURE 2 )..................................... variegatus species group

– Mesosternum densely tesselate with minute to indistinct punctures. Basal triangle finely rugose-areolate and transversally ridged, without transverse carina ( Fig. 7D View FIGURE 7 ). Propodeum rounded in lateral view. Inner hind tibial spur with short and contiguous spine (e.g. Figs 2B, 2E View FIGURE 2 ). Axilla black. Base of metasoma black (at most with marginal zones discoloured, see Fig. 7E View FIGURE 7 )........................................................................................ garrulus species group

Male

1 – Scape not to weakly dilated, tubular to slightly conical. Face without depression (e.g. Fig. 3D View FIGURE 3 )...................... 2

– Scape moderately to strongly dilated, oblong to trapezoidal. Face with a crescent-depressed area below antennae (e.g. Figs 3A, 3G View FIGURE 3 , 6A, 6F, 6K View FIGURE 6 )................................................................................... 5

3 – Scape with conspicuously sinuate anterior margin. Crosspoint of episternal sulcus and omaulus with very deep pit anteriorly bordered by conspicuous carina. Mesosternum conspicuously concave medially, concavity bordered by a pair of protuberant humps. S3(–4) usually with triangular callus medially. Ventral face of gonoforceps remarkably protruding.............................................................................................. H. signatus (Panzer, 1798)

– Scape with straight to slightly convex anterior margin. Crosspoint of episternal sulcus and omaulus without deep pit or sharp carina. Mesosternum more or less flat, without pair of humps. S3(–4) flat. Ventral face of gonoforceps flat to slightly convex. ................................................................................................... 4

4 – Punctures on mesepisternum much coarser than on scutum. Punctures on clypeus close to dense, at least as coarse as on frons. Basal triangle tapering posteriorly into broad triangular area. S7 with long and narrow basal lobe, basal lobe much longer and narrower than distal lobe, distal lobe glabrous. S8 apically produced into narrow spine. Gonoforceps with basal depression. Penis valves sinuate at their basal crosspoint (in dorsal view), inner surface swollen. Outline of aedeagus circular in dorsal view............................................................................. H. duckei (Alfken, 1904)

– Punctures on mesepisternum at most hardly coarser than on scutum. Punctures on clypeus scattered, shallow and much finer than on frons. Basal triangle reduced posteriorly into narrow linear furrow. S7 subtriangular to L-shaped, with broad and short basal lobe, basal lobe about as long and as broad as distal lobe, distal lobe with long and plumose hairs ( Fig. 4F View FIGURE 4 ). S8 with broad subtruncate to sinuate tip ( Fig. 4G View FIGURE 4 ). Gonoforceps without basal depression. Penis valves sharply angular at their basal crosspoint (in dorsal view), inner surface flat or concave ( Fig. 4H View FIGURE 4 ). Outline of aedeagus oblong in dorsal view, with subparallel side ( Fig. 4H View FIGURE 4 )........................................................................ gibbus species group

5 – Posterior face of scape with broad longitudinal furrow. Basal triangle deeply rugose-areolate, with conspicuous transverse carina (e.g. Fig. 2G View FIGURE 2 ). Propodeum sharply angular in lateral view. Axilla usually yellow. S3(–4) usually with pair of humps medially ( Fig. 3I View FIGURE 3 ), more rarely flat..................................................... variegatus species group

– Posterior face of scape entirely concave. Basal triangle finely rugose areolate and transversally ridged, without transverse carina ( Fig. 8D View FIGURE 8 ). Propodeum rounded in lateral view. Axilla black. S3, if not flat, with medial U-shaped elevation ( Figs 3C View FIGURE 3 , 6C, 6H View FIGURE 6 ) or with transverse keel ( Fig. 6M View FIGURE 6 )..................................................................... 6

6 – Scape slightly dilated (0.5× as wide as long) with broadly rounded antero-apical angle ( Fig. 3A View FIGURE 3 ). Volsella with long and acute digitus ( Fig. 4D View FIGURE 4 ). Inner surface of penis valve swollen with distinct dorsal flattening ( Fig. 4C View FIGURE 4 ). Penis valve without long and free membranous ventral subapical lobe nor deep fovea above it ( Fig. 4E View FIGURE 4 ). Tibiae usually red and yellow. T1–2 usually red ( Fig. 3B View FIGURE 3 )........................................................................ H. gazagnairei (Vachal, 1891)

– Scape moderately dilated (0.8× as wide as long) with produced and angular antero-apical angle ( Figs 6A, 6F, 6K View FIGURE 6 ). Volsella with short and blunt digitus ( Fig. 8H View FIGURE 8 ). Inner surface of penis valve uniformly flat to slightly concave ( Figs 6D, 6I, 6N View FIGURE 6 ). Penis valve with long free membranous ventral subapical lobe and, with deep and large fovea above it ( Figs 6E, 6J, 6O View FIGURE 6 ). Tibiae black with small yellow basal spot. T1–2 black ( Fig. 8E View FIGURE 8 ).......................................... garrulus species group