Acalles krasnodarensis Stüben, 2025

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 : 242-244

Acalles krasnodarensis Stüben sp. nov.

urn:lsid:zoobank.org:act:6F7FE0E9-7350-4BC0-B954-9625FCB3939D

( Fig. 5 )

Type material

Holotype: 1♀, ‘ Russia, Krasnodar: Krasnaya Polyana env., 43°41’17”N, 40°12’20”E, 720 m, 22.07.2014, leg. A. V. Kovalev’, coll. ZFMK, collector no. 2759-PST, GenBank: MF426966 (was previously a paratype of A. ossetiensis Stüben, 2018 ); for photo documentation see Fig. 5 // Paratypes: 1♂, ‘ USSR, Caucasus occ., Krasnaya Polyana, 1500 m, leg. Borovec’ , ‘ 60 km E Adler pr. Sochi , 30.5.1985 ’, coll. Stüben / 1♀, ‘ Russia, Krasnodar: Chvizhepse vill. env., 43°38’32”N 40°04’45”E, 300 m, 11.07.2014, leg. A. V. Kovalev’, coll. Stüben; collector no. 2756-PST, GenBank : MF426965 (was previously a paratype of Acalles ossetiensis Stüben, 2018 ) / 1 ♀, ‘NW Caucasus , Adygeya rep., 14.7.1998, Kamennomostskij, lgt. Kopecký & Svarc’, coll. Stüben-SDEI (col. 21432) .

Note. Holotype and one paratype are from the paratype series of Acalles ossentiensis Stüben, 2018 from Krasnodar ( Russia).

Preliminary remark: Acalles ossetiensis from southern Ossetia, which I described in 2018, also needs to be further split up after molecular analyses, and finally morphological studies made it very clear that it is another independent North Caucasian Acalles species from the Russian Krasnodar Territory and the Republic of Adygea. Both species were very often identified in the past as the very similar Acalles echinatus ( Germar, 1824) , especially from Eastern Europe, but this is certainly not supported by more recent molecular studies (see Fig. 1 and Appendix 1).

Length. 1.5–2.3 mm (without rostrum).

Head & Rostrum. Eyes large, readily visible in dorsal view, considerably overlapping upper margin of antennal groove; rostrum of females microscopically finely punctate, straight, shiny, long and narrow, length/width ratio of 5 (measured between the insertions of the antennae). Last five funicular antennomeres as long as broad, trapezoidal, not clearly separated from very large, wide club; first two segments elongate.

Pronotum. Only slightly longer than wide; widest behind middle, laterally evenly strongly rounded, but narrowing in a straight line directly behind front margin. Pronotal disc (lateral view) evenly rounded over entire length, slightly curved, always clearly separated from elytra. In dorsal view without keels or tubercles, but with strong, deep side by side punctures, without shallow interspaces; each puncture with a short and broad white or brown bristle; broad, short, light scales, which lie close to the underlying cuticle, particularly visible on flanks of pronotum.

Elytra. Obovate, narrowly rounded apically; 1.2× as long as wide; widest at end of first quarter behind base. In lateral view outline of elytra with a flat curve then regularly arcuate toward apex. Base of elytra slightly convex towards pronotum. Integument with white, beige and brown, circular and short oval non-overlapping scales, which do not obscure underlying cuticle; white scaly patch present on scutellum and just behind base on first interval, a few more irregularly limited light patches scattered on elytra; white crossband visible on first intervals of elytral declivity behind middle. Striae deeply punctate, intervals increasingly convex towards lateral margins; bearing a row of a few short, strongly inclined, white and brown bristles that are twice as long as wide; dark brown shiny cuticle not obscured by scales.

Legs. Long, front femora reaching foremargin of eyes, hind femora extended beyond elytral apex, covered with long, narrow, white, only slightly raised bristles.

Underside. Rostrum channel deep, very narrow between procoxae, about half as wide as channel at anterior margin of prosternum; channel ending in semicircular mesosternal receptaculum between the mesocoxae. All abdominal ventrites covered with light, long, widely spaced bristles, which lie close to cuticle.

Female genitalia. See Fig 5 and differential diagnosis.

Differential diagnosis

Acalles krasnodarensis is closely related to Acalles ossetiensis Stüben 2018 from South Ossetia, but differs from it in a number of characteristics. Only females are used here for comparison: Rostrum of females at least 5 times longer than wide between the antenna insertions (in O. ossetiensis much shorter, at most 4.1 times longer than wide); dense, broad and deep pronotal punctation (which in A. ossetiensis is finer, less deep and characterised in places on the disc by broad shiny spaces); elytra more elongate, pointed oval, inverted ovate (versus shorter, more rounded towards the apex in A. ossetiensis ); outer elytral intervals in particular strongly convex (versus only slightly convex); pronotum scales, especially well recognisable on the flanks, broader, short oval (versus clearly slimmer, long oval or spindle-shaped in A. ossetiensis ); styli of the gonocoxite narrower and almost twice as long in the new species; and cornu of the spermatheca more curved (flatter in C. ossetiensis ).

Molecularly, these two species are relatively far apart in the mtCO1 gene (659bp). The p-distance here is between 7.9% and 9.1%, a comparatively very high value for the species of the subtribe Tylodina (see Schütte et al. 2023 for more details). To the next related taxon Acalles echinatus ( Germar, 1824) , a population near Moscow, with which both species from the Caucasus have obviosly always been equated due to the similar shape of the aedeagus, this value is 18.5% ( Fig. 1 , Appendix 1).

Immediately before this article went to press, R. Borovec ( Czech Republic) provided me with a very small male (1.5 mm) from the type locality of Krasnaya Polyana area of the Krasnodar Territory ( Russia), which L. Dieckmann had already (erroneously) identified as Acalles echinatus Germar in 1986. In contrast to this species, which is mainly distributed in Central and Eastern Europe, and Acalles ossetiensis , the median lobe of the aedeagus of A. krasnodarensis is clearly broader ventrally and more curved over its entire length when viewed laterally (see Figs. 5 and 6 , top right).

Distribution. This species is so far known only from the eastern Black Sea coast in the vicinity of the town of Chvizhepse in the Russian province of Krasnodar, but it is likely to have a much wider distribution.

Derivatio nominis. This species is named after the Russian province of Krasnodar (Krasnodarskij kraj).

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).

FIGURE 5. Habitus and female genitalia (A. Ovipositor, B. Spiculum ventrale, C. 7. and 8. Tergite, D. Spermatheca) of the holotype of Acalles krasnodarensis sp. nov. / Top right: Aedeagus (ventral / lateral) of another paratype.

FIGURE 6. Habitus and female genitalia (A. Ovipositor, B. Spiculum ventrale, C. 7. and 8. Tergit, D. Spermatheca) of the paratype of Acalles ossetiensis Stüben, 2018 (Georigia: South Ossetia) / Top right: Aedeagus (ventral/lateral) of paratype.