Andrena (Graecandrena) balticola WOOD, 2024, spec. nov.
Creators: name: WOOD, T. J.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Andrenidae
Andrena
Andrena balticola

description: Andrena (Graecandrena) balticola spec. nov.
Figures 65A–H.
HOLOTYPE: ESTONIA: Tartu, Kalmistu paljand, 58.3948 oN, 26.7098 oE, 11.v.2008, ♀, leg. V. Soon, TUZ (code: TUZ 051846).
Description: Female: Body length: 5.5 mm (Figure 65A). Head: Dark, 1.15 times wider than long (Figure 65B). Clypeus strongly domed, irregularly and shallowly punctate, punctures separated by 1–3 puncture diameters, underlying surface with even granular shagreen, weakly shining (Figure 65C). Process of labrum narrowly trapezoidal, slightly longer than wide. Gena subequal to width of compound eye; ocelloccipital distance slightly less than ½ diameter of lateral ocellus. Foveae dorsally moderately broad, occupying ½ space between compound eye and lateral ocellus, ventrally only narrowly slightly at level of antennal insertions; foveae filled with light brown hairs (Figure 65D). Face, gena, vertex, and scape with short whitish hairs. Antennae basally dark, A4–12 ventrally lightened by presence of brownish scales; A3 exceeding A4, shorter than A4+5, A4 and A5 subquadrate, slightly wider than long.
Mesosoma: Scutum and scutellum finely shagreened, weakly shining, with weak metallic green-copper reflections; surface finely and obscurely punctate, punctures separated by 2 puncture diameters, individual punctures difficult to discern against background sculpture (Figure 65E). Pronotum rounded. Mesepisternum with fine granular shagreen, shining. Dorsolateral parts of propodeum with strong granular microreticulation, dull; propodeal triangle laterally without carinae, surface with strong granular microreticulation overlain almost entirely with dense network of irregular winding rugae, propodeal triangle thus defined by change in surface sculpture (Figure 65F). Mesepisternum almost hairless, dorsally with sparse densely plumose and sub-squamous light brownish hairs, becoming shorter on scutum and scutellum. Propodeal corbicula incomplete, dorsal fringe long, composed of plumose yellowish hairs, internal surface with occasional long yellowish simple hairs. Legs brownish, hind basitarsi lightened orange, pubescence light brown. Flocculus complete, composed of light brownish plumose hairs; femoral and tibial scopae composed of whitish simple hairs. Hind tarsal claws with inner tooth. Wings hyaline, stigma and venation orange-brown, nervulus strongly antefurcal (Figure 65G).
Metasoma: Tergal discs dark, T1 with apical rim narrowly lightened hyaline, T2–4 with marginal areas more broadly lightened hyaline-brown (Figure 65H). Tergal discs with regular granular microreticulation, weakly shining, surface impunctate. T2–4 apically with narrow hairbands, broadly interrupted on T2, slightly interrupted on T3, complete on T4, not greatly extending beyond apical rim of marginal areas, hairbands obscuring underlying surface. Apical fringe of T5 and hairs flanking pygidial plate golden-brown. Pygidial plate large, rounded triangular, surface with fine granular microreticulation, broadly shining.
Male: Unknown.
Diagnosis. Andrena balticola presents an unusual combination of morphological characters. Due to the small body size, moderately developed facial foveae that are not strongly narrowed ventrally, hind tarsal claws with inner tooth, propodeal triangle that is not laterally defined by raised carinae (no carinae present) but which has the internal surface entirely covered with a dense network of irregular winding rugae, and strongly antefurcal nervulus, it does not neatly fit into the typical Andrena subgenera. It cannot be an Aciandrena, since the hind tarsal claws have an inner subapical tooth, and the propodeal triangle is clearly covered in rugae. It also does not fit the concept any groups within the subgenus Micrandrena, since the propodeal triangle lacks lateral carinae, the foveae are not strongly and linearly narrowed ventrally (longibarbis -species group), and the nervulus is strongly antefurcal. The best placement is therefore in the subgenus Graecandrena Warncke, 1968 due to these aforementioned characters. It differs from most members of the subgenus due to the more extensive network of rugae on the propodeal triangle, whereas most European Graecandrena have only a small area with rugae basally (e.g. A. graecella Warncke, 1965; A. hyemala Warncke, 1973). However, this character is variable as A. verticalis Pérez, 1895 (which can be confidently placed in the Graecandrena based on genetic evidence; Pisanty et al. 2022b) lacks any rugae on the propodeal triangle. Ultimately the location of the male with a typical Graecandrena genital capsule or genetic work will be necessary to confirm or disprove this phylogenetic placement (as well as more precisely defining the boundaries of the subgenus itself).
The most morphologically similar species are A. (incertae sedis) orichalcum Wood, 2023 (southern Turkey, northern Syria *) and A. (Graecandrena) schwarzi Warncke, 1975 (Ukraine, European Russia, Turkey, Kazakhstan), though it should be noted that A. schwarzi has not been confirmed to fall within the Graecandrena due to a lack of genetic data. Due to the scutum of A. balticola which has weak metallic greenish-copper reflections (Figure 65E), it can be compared to A. orichalcum which is tentatively but not definitively associated with the subgenus Graecandrena. Andrena balticola can be separated by the sparse and obscure scutal punctation, punctures separated by 2 puncture diameters, individual punctures difficult to discern against background sculpture (in A. orichalcum scutum with punctures separated by 1–2 puncture diameters, individual punctures clear and easily visible against underlying surface), facial foveae relatively broad, occupying ½ space between compound eye and lateral ocellus (Figure 65D), not noticeably narrowed ventrally (in A. orichalcum with foveae occupying ⅓ to ¼ of the space between compound eye and lateral ocellus, narrowed further ventrally), clypeus with sparse, shallow, and obscure punctation, punctures separated by 1–3 puncture diameters (in A. orichalcum with clypeus more densely and clearly punctate, punctures separated by 0.5–2 puncture diameters), and terga with narrow apical hairbands on T2–4 (Figure 65H), hairbands extending only slightly beyond the apical margin of the marginal areas (in A. orichalcum with long hairbands on T2–4, hairbands clearly extending far beyond the apical margins of the marginal areas).
Separation from A. schwarzi can be made using similar characters, specifically A. balticola has the scutum with weak metallic greenish-copper reflections (completely black in A. schwarzi), weak scutal punctation blending into clear scutal sculpture, scutum weakly shining (in A. schwarzi with the scutum polished and shining with deep distinct punctures), the clypeus is shagreened and weakly shining, with obscure shallow punctation (in A. schwarzi with the clypeus polished and shining, with deep distinct punctures), and the tergal hairbands are short and barely surpass the apical margin of the marginal areas (in A. schwarzi with the apical hairbands of T2–4 clearly extending far beyond the apical margins of the marginal areas).
Remarks. Based on the distribution, it could be expected that A. balticola might be conspecific with A. (Aciandrena) volgensis Osytshnjuk, 1994 (southern European Russia and Kazakhstan) or A. (Aciandrena) chersona Warncke, 1972 (Ukraine to Turkey, the Caucasus, northern Iran, and Turkmenistan) as these species are found in dry open habitats in eastern Europe. However, these are clearly members of the subgenus Aciandrena because the propodeal triangle is covered in the typical granular shagreen found in members of this subgenus, and the facial foveae are more clearly narrowed ventrally. It seems remarkable that this taxon has not previously been recognised from European Russia. If this was an older specimen, it could be suggested that it had been mislabelled, but this specimen was collected recently during a survey of known providence. New surveys at the locus typicus (which is a small park on sandy soil along the Emajõgi river) have unfortunately not revealed any new specimens (V. Soon, in litt.), but other surveys in sandy habitats across the Baltic region may produce additional material, including males.
Etymology. From the Latin Balticus, the name for the geographic region comprising Estonia, Latvia, and Lithuania with the suffix -cola, meaning “living in”.
Distribution. Estonia, probably present in at least neighbouring Latvia and European Russia.
Other material examined (Andrena orichalcum) SYRIA: Jabbul-See, SE Aleppo, 300 m, 19.iv.1992, 16♀, leg. K. Warncke, OÖLM.
description: Published as part of WOOD, T. J., 2024, Further revisions to the Palaearctic Andrena fauna (Hymenoptera: Andrenidae), pp. 1-150 in Zootaxa 5483 (1) on pages 103-106, DOI: 10.11646/zootaxa.5483.1.1, http://zenodo.org/record/13209307