Cryptorhynchinae

Stüben, Peter E., 2025, New species and an image key to the wingless Cryptorhynchinae of the Caucasus (Coleoptera: Curculionidae: Tylodina) - a hypothesis on the spread of forest and open land species in the Western Palaearctic, Zootaxa 5647 (3), pp. 235-259 : 244-252

Image key to the wingless Cryptorhynchinae of the Caucasus

Note. A reliable and quick identification can be made via the aedeagus of the males (see also Fig. 1 ). Only then should the females be assigned on the basis of the elytra scales and bristles from the same locality. Sifting of wingless Cyptorhynchinae, the main method by which they are collected, always contains a large number of specimens, almost always including males.

1 Base of each elytron strongly S -shaped, protruding towards the pronotum with corners that extend far forward. Length: 3.0– 4.9 mm .................................................................... Acallocrates colonnellii Bahr, 2003

1* Base of the elytron straight or only slightly convex over the entire length protruding towards the pronotum.............. 2

2 Male with a distinct (strongly sclerotised) sclerite (= inner sac structure) in the endophallus.......................... 3

2* Males without a recognisable, strongly sclerotised (more or less complex) sclerite in the endophallus (instead sometimes with a blurred, ‘cloudy’ appearing endophallus consisting of many tiny hooks).......... Onyxacalles & Echinodera ........ 11

3 Males with a strongly sclerotised, elongate, parallel-sided or X-shaped sclerite in the endophallus, basally (sometimes also apically) with a closed or semicircularly open structure (see couplet 2)......................... Kyklioacalles ………. 4

3* Males with sclerite in the endophallus differently shaped (without a circular or only semicircularly opened structure)...... 6

--- Kyklioacalles ---

4 Elytra with patches of pale scales (‘eyespots’) absent, instead with light-coloured, irregularly delimited, cloudy markings on the elytra and a prominent X-shaped inner sac structure of the aedeagus; tiny species: <2.3 mm ............................................................................................... Kyklioacalles reitteri ( Meyer, 1896)

4* Elytra with two patches of pale scales (‘eyespots’) at the centre of the elytra and a strongly sclerotised, elongate, parallel-sided sclerite in the endophallus (basal or apical with a circular structure)............................................. 5

5 Larger species,> 3.5 mm; with a long, bottle-necked tip of the aedeagus (couplet 4*, left). Length: 3.5–5.2 mm ........................................................................... Kyklioacalles ocellus Stüben & Astrin, 2025

5* Smaller species, <3.0 mm; with a rounded tip of the aedeagus (couplet 4*, right). Length: 2.0–3.0 mm.................................................................................... Kyklioacalles chaudoirii ( Hochhuth, 1847)

6 Pronotal disc and elytra with conspicuously circular, large, partly overlapping scales, which largely obscure the underlying cuticle. Elytral intervals with short, widely protruding, vertically erect bristles................ Caucasusacalles ………. 7

6* Pronotal disc and elytra predominantly with narrower, drop-shaped, slender or short-oval adjacent scales, which usually do not obscure the dark brown, shiny underlying cuticle. Elytral intervals either with dense comb-like brush or tufts or only a few strongly inclined, club-shaped bristles........................................................ Acalles ………. 9

--- Caucasusacalles ---

7 Sclerite of the endophallus with a parallel-sided basal structure consisting of two narrow, closely spaced bars, each apical with an inwardly inclined long, spine-like tip. Length: 1.9–2.5 mm ............. Caucasusacalles subglobosus Stüben sp. nov.

7* Sclerite of the endophallus with a parallel-sided basic structure consisting of widely spaced bars, which are connected apically by a pointed, weakly sclerotised bridge.................................................................... 8

8 Sclerite of the endophallus with only two simple, subparallel bars (couplet 7*, left); median lobe of the aedeagus much longer, but at least 2× longer than wide. Length: 1.8–2.2 mm ........................... Caucasusacalles lederi ( Meyer, 1896)

8* Sclerite of the endophallus with further angularly separated, characteristic protuberances in the basal area as well as strongly curved ends (couplet 7*, right); the median lobe of the aedeagus considerably shorter, nearly as wide as long. Length: 2.1–2.5 mm .............................................................. Caucasusacalles circularis Stüben sp. nov.

--- Acalles ---

9 Elytral intervals with numerous, towering condensations or tufts of bristles on the elytral intervals; inner sac of the aedeagus in the shape of a Greek ‚Omega’. Length: 3.0–4.0 mm................................ Acalles (s.l.) milleri Reitter, 1883

9* Elytral intervals without such tufts of bristles or conspicuous narrowly arranged accumulations of bristles on the elytral intervals; inner sac of the aedeagus consisting of two simple parallel stripes.............................................. 10

10 Rostrum of females much shorter, at most 4.1 times as long as wide between antennal insertions; elytra shorter, more rounded towards the apex (couplet 9*, left); punctation of the pronotum finer, less deep and more separated on the disc; scales narrower. Length: 1.8–2.3 mm ......................................................... Acalles ossetiensis Stüben, 2018

10* Rostrum of females at least 5 times as long as wide between antennal insertions; elytra more elongate, pointed oval or inverted ovate (couplet 9*, right); pronotum with dense, broad, deep punctures, scales much wider, drop-shaped. Length: 1.5–2.3 mm .................................................................... Acalles krasnodarensis Stüben sp. nov.

11 Eyes large, clearly protruding (up to half the diameter of the eye) over the upper edge of scrobe; median lobe of aedeagus (ventral) short, only slightly longer than wide............................................ Onyxacalles ………. 12

11* Eyes small, not exceeding the upper edge of the scrobe; median lobe of the aedeagus long (‘rocket-shaped’), many times longer than wide......................................................................... Echinodera ………. 14

--- Onyxacalles ---

12 Elytra with strong tubercles on the outermost 3 intervals; elytral bristles inconspicuous, short, very fine, strongly inclined and curved; median lobe of aedeagus tapering to a pointed triangle when viewed ventrally. Length: 2.8–4.0 mm............................................................................. Onyxacalles gibbosus Stüben & Astrin, 2025

12* Elytra without strong tubercles (outer intervals at most jagged); elytral bristles broader, club-shaped, longer and forming a ‘crown-shape’; median lobe of aedeagus more rounded or with a bottleneck-like tip............................... 13

13 Elytral intervals with punctures deep and broad, especially on the outermost striae, extended to the intervals, giving the elytra a jagged outline; median lobe of the aedeagus simply pointed (couplet 12*, left). Length: 2.2–3.8 mm ....................................................................................... Onyxacalles caucasicus (Reitter, 1891)

13* Elytral intervals elevated, but without deeply and heavily punctate surface; median lobe of the aedeagus with a bottleneck-like tip (couplet 12*, right). Length: 3.3.– 3.5 mm .......................... Onyxacalles georgius Stüben & Krátký, 1918

--- Echinodera ---

14 Eyes smaller and oval; clearly placed on the sides of the head; aedeagus with an ‘S-shaped’ long, tapering, not sclerotized (“translucent”) apex; integument of the smaller species (<3.4 mm) (light) brown... Subgenus: Echinodera s.str. ………. 15

14* Eyes larger and mostly round; visible as a narrow strip when viewed from above; aedeagus either simply rounded or protruding bottle-shaped at the apex (but never with an S -shaped, transparent tip); clearly larger, dark brown to black species (> 4 mm)............................................................................. Subgenus: Ruteria ………. 18

--- Echinodera s. str. subg.---

15 Spine at the end of the hind tibia of males curved inwards at almost a right angle. Length: 2.2–3.0 mm........................................................................................ Echinodera davidiani Savitsky, 1999

15* Spine at the end of the hind tibia of males straight or weakly curved............................................ 16

16 Elytra longer, obovate, apex rounded narrowly oval; elytral bristles very short (at most 1.5× longer than wide)). Length: 2.6–3.4 mm ............................................................. Echinodera orientalis (A. & F. Solari, 1907)

16* Elytra wider, short ovally rounded with apex more broadly rounded; elytral bristles longer (2×–4× longer than wide)..... 17

17 Elytral bristles very long, 3.5×–4× longer than wide (couplet 16*, left); striae and the punctures between the outermost elytra intervals narrow; median lobe of aedeagus strongly curved towards the tip when viewed ventrally. Length: 2.2 mm ..................................................................... Echinodera borjomiensis Stüben & Astrin, 2025

17* Elytral bristles short, only 2×–2.5 x longer than wide (couplet 16*, right); elytral striae strongly punctate between the narrower outermost elytra intervals; median lobe of aedeagus nearly flat when viewed laterally. Length: 1.9–3.1 mm .................................................................................... Echinodera horridula ( Reitter, 1888)

--- Ruteria subg. ---

18 Sides of the pronotum with light brown and white scales; aedeagus with a narrow, elongate apex. Length: (2.7) 4.0– 5.6 mm. Note. According to Savitsky (1997), the central, southern and southeastern European species is also said to occur in Georgia (the species was described from Austria, Styria). Savitsky mentions only 2 females and 1 male (it remains unclear whether the aedeagus shown is from this male.). In order to take this unusual disjunct distribution into account, the species is also mentioned here for the Caucasus , despite considerable doubt (to facilitate subsequent identification)........................................................................................ Echinodera (Ruteria) hypocrita (Boheman, 1837)

18* Sides of the pronotum with dark brown or black scales; aedeagus not protruding like a bottle neck at tip. Note. So far, molecular data from this group are only available for E. teplovi . Therefore, I follow here the exclusively morphological differential diagnosis of Savitsky, 1997, as far as it seemed comprehensible to me after examination of the type material (see illustrations of the habitus of holotypes). I supplement with illustrations of the aedeagus; however, further studies are urgently needed here on the generally poorly researched species of the subgenus Ruteria from the Caucasus ............................................................................... Echinodera anatolica group ………. 19

19 Elytra with 7th stria at end of basal 1/4 abruptly ending; mesosternal part of receptaculum with distinct tubercle; aedeagus slender, tapered. Length: 4.0– 5.5 mm .............................. Echinodera (Ruteria) kakhetica ( Savitsky, 1997) (probably a synonym of E. hyrcania , see comment Stüben, 2018: 367)

19* Elytra with 7th stria not abruptly ending at the end of basal ¼; mesosternal part of receptaculum usually without tubercle.... .................................................................................................. 20

20 Middle part of metathorax and ventrite 1 covered with dissected scales; uncus of fore tibia in male beveled triangular, split (see couplet 20); apical part of ventrite 1 strongly sloping, at nearly right angle to plane of ventrite 2; aedeagus broader, obtuseangled (dorsal view). Length: 4.1–4.9 mm ......................... Echinodera (Ruteria) meskhetica ( Savitsky, 1997)

20* Middle part of metathorax and ventrite 1 covered with elongate undissected scales; uncus of fore tibia in male of different shape; apical part of ventrite 1 slightly or moderately sloping to plane of ventrite 2................................ 21

21 Body of male 1.78–1.85, of female 1.77–1.91, times as long as wide; anterior part of receptaculum covered with hairs and admixture of scales divided into several filiform lobes; uncus of fore tibia in male wide; aedeagus wider towards the tip. Length: 4.0– 5.5 mm .................................................. Echinodera (Ruteria) hyrcanica ( Savitsky, 1997)

21* Body of male 1.58–1.77, of female 1.59–1.80, times as long as wide; anterior part of receptaculum covered with hairs and sparse narrow scales divided into 2 filiform lobes; uncus of fore tibia in male weakly dilated; aedeagus with clearly bent tip (lateral view). Length: 3.9–5.0 mm.................................. Echinodera (Ruteria) teplovi ( Savitsky, 1997)

Figures

FIGURE 1. Bayesian 50% majority rule consensus based on the mtCO1 partial gene (Folmer region, 658 bp) for newly sequenced Caucasian Cryptorhynchinae (“ZFMK”), expanded by additional specimens (“MWI”). Numbers indicate nodal posterior probabilities. The scale shows the expected nucleotide substitutions per site. Rough collecting locations are added (GE=Georgia; AM=Armenia).The place of discovery is followed by the collection number. Evaluation and comments on the dendrogram can be found in the differential diagnoses of the new species. For the CO1-distance matrix of the sequenced specimens/species see Appendix 1 and the GenBank numbers in Stüben et al. 2025 as well as the CO1 Barcodes of the new species—highlighted here in red—in Appendix 2. The aedeagi are added to the right as small images. They are an excellent tool for quickly and accurately identifying species that are very similar in appearance (see also the picture identification key below).

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