Colletes perplexus sp. nov.

Fig. 1 A – F

Type material (3 specimens).

Holotype: ♂. Azerbaijan. • “ Azerbaijan, Nakhchivan AR, Ordubad, Kotam, 700 m, 38°53'25"N, 46°03'14"E, 19. V. 2025, leg. Proshchalykin, Maharramov ” (ZISP). Paratypes. Azerbaijan. • “ Azerbaijan, Nakhchivan AR, Ordubad, Bilav, 1050 m, 39°02'43"N, 45°49'07"E, 22. V. 2025, 2 ♂ Proshchalykin, Maharramov ” (FSCV / RCMK).

Diagnosis.

The new species belongs to the C. nanus species group that is characterised in the male sex by overall small size (maximum body length ~ 9.0 mm), malar area elongate, mesoscutal disc polished, either impunctate or sparsely punctate, anterior declivorous part of T 1 densely covered with short appressed and long erect hair, T 1 – T 5 and S 2 – S 5 with dense and broad white apical hair bands (Noskiewicz 1936). This group is particularly speciose in deserts and semi-deserts of North Africa and the Middle East. Far fewer species occur in the Caucasus region and Middle Asia, namely C. popovi Noskiewicz, 1936, C. schwarzi Kuhlmann, 2002 and the enigmatic C. penulatus Noskiewicz, 1936. The latter species is known only from the single female holotype and, thus, is not considered here (but see comment below under Remarks). In neighbouring Iran, C. sirjanensis Kuhlmann, 2023 was described based on males but its oval-shaped S 7 (Kuhlmann et al. 2023) differs significantly from the ± round S 7 of C. perplexus, C. schwarzi and C. popovi, hence, it is also not included here. Therefore, the diagnosis is limited to these three closely related species, which are the only others of the C. nanus species group found in the region and share a very similar morphology. They are extensively illustrated in this paper to facilitate their identification.

The recently described C. storozhenkoi Kuhlmann & Proshchalykin, 2025 (Proshchalykin and Kuhlmann 2025) is also not considered here. The species is also known only from females collected at a single site in Dagestan in the coastal lowlands of the Caspian Sea and the following morphological features suggests that C. storozhenkoi and C. perplexus very likely represent two separate taxa. In C. storozhenkoi punctation on the mesoscutal disc unusually dense for a species in this group (much more dispersed in C. perplexus), hair on mesoscutum in particular posteriorly short and thickly plumose (C. perplexus: disproportionately longer, more slender, and less plumose), horizontal part of propodeum shorter (C. perplexus: disproportionately longer) and depressions of apical tergal margins differ disproportionally for sexes of the same species. However, this can only be clarified ultimately if the unknown sex of at least one of the two species is found or through genetic analysis (e. g. DNA barcoding), which was not feasible within the context of this study.

The male of C. perplexus differs from C. popovi and C. schwarzi by the following character combination: Apical tergal hair bands narrower (Fig. 1 C) than in the other species (Fig. 1 G, K), appressed hair on the sloping base of T 1 sparser and more restricted, barely reaching the disc (Fig. 1 D) (appressed hair denser and more extensive in C. schwarzi and C. popovi as in Fig. 1 H, L), punctation on discs of T 1 and T 2 fine and dense (i <d) (Fig. 1 D) (in C. popovi more dispersed (i = 1–2 d) as in Fig. 1 L), apical sternal hair fringes medially significantly shorter than laterally (Fig. 1 B) (in C. popovi fringes only slightly shorter medially), S 7 overall and especially apically more evenly rounded (Fig. 1 F) while apically rather flattened or a bit emarginate in C. schwarzi and C. popovi (Fig. 1 J, N), gonostylus basally slightly broader and of different shape (Fig. 1 E) than in the other two species (Fig. 1 I, M).

Description.

Female. Unknown.

Male. Body length = 7.0–8.0 mm. Head. Head wider than long (width to length ratio: 1.3: 1). Integument black except tip of mandible partly dark reddish-brown. Face densely covered with long, white to yellowish-brown, erect hairs; on vertex partly darker brown. Malar area medially ~ 3 / 4 as long as width of mandible base, finely striate. Antenna dorsally dark blackish-brown to black, ventrally slightly lighter; F 1 as long as wide (length to width ratio: 1: 1). Mesosoma. Integument black. Dorsolateral angle of pronotum rectangular and rounded. Mesoscutal disc sparsely punctate (i = 1–3 d), interspace smooth and shiny. Scutellum anteriorly almost impunctate, smooth and shiny, posteriorly densely punctate. Mesoscutum, scutellum, metanotum, mesepisternum and propodeum covered with long, yellowish-brown, laterally white erect hair (Fig. 1 A). Wings. Transparent, membrane very slightly light yellow; wing venation yellowish-brown to blackish. Legs. Integument black; last tarsal segment at least partly, usually completely brown. Hind basitarsus ~ 4 × as long as wide. Vestiture white to yellowish-white (Fig. 1 A). Metasoma. Integument black; depressed apical tergal margins dark yellowish to dark reddish translucent (Fig. 1 C, D). T 1 in anterior half densely covered with short appressed white to yellowish-white hair, T 1 entirely and T 2 on disc medially with sparse long and erect, and T 2 anteriorly sparsely covered with long, erect white to yellowish-white hairs (Fig. 1 C, D); apical tergal hair bands dense and broad, white to yellowish-white (Fig. 1 C, D). Apical sternal hair fringes medially significantly shorter than laterally (Fig. 1 B). Terga densely and finely punctate (i ≤ d), interspace smooth and shiny (Fig. 1 C, D). Terminalia. Genitalia and S 7 as illustrated (Fig. 1 E, F).

Etymology.

The species name perplexus refers to the Latin term for “ enigmatic ” or “ ambiguous ”, since the specimens could potentially represent the unknown male of C. penulatus Noskiewicz, 1936 (see below comment under “ Remarks ”).

General distribution.

Only known from the type locality in southern Azerbaijan.

Floral hosts.

Unknown.

Seasonal activity.

May.

Remarks.

It cannot be ruled out that the specimens described here as a new species is the unknown male of C. penulatus. They belong to the same species group and were found in the same region (valley of the river Ares, formerly Araxes). The type specimen of C. penulatus, a single female, was placed in Noskiewicz' collection (Noskiewicz 1936: 287) but the specimen is not there (Wanat et al. 2014). The type is probably lost, so its identity cannot be determined with certainty at present.