Istrianis Meyrick, 1918

Bidzilya, Oleksiy & Karsholt, Ole, 2015, Revision of the genus Istrianis Meyrick, 1918 (Lepidoptera, Gelechiidae) with special regard to the Palaearctic region, Zootaxa 4059 (3), pp. 401-445 : 404-406

Genus Istrianis Meyrick, 1918

Istrianis Meyrick, 1918: 130 . Type species: Istrianis crauropa Meyrick, 1918 , by original designation and monotypy. Pseudoteleia Amsel, 1935: 299 . Type-species: Pseudoteleia squamodorella Amsel, 1935 , by original designation and monotypy. [Synonymized by Bidzilya & Mey 2011: 25].

Description. Head smooth-scaled; labial palpus slender, moderately upcurved, segment 2 about two times broader and nearly 1.5 times longer than segment 3,with short brush of modified scales on underside; proboscis welldeveloped; antenna simple; ocelli absent. Clypeus with ventral margin truncate ( Lee & Brown 2008a).

Thorax. Tegulae usually of same colour as thorax. Scutellum at anterior margin with rounded plate of very short, modified scales. Posterior margin of metascutum with paired group of long hair-like scales. Forewing Wingspan 7.6–13.1 mm; forewing of I. myricariella , I. arenicolella and I. wachtlii with costal fold to 1/ 3 in male; male forewing of I. femoralis with basal pocket with pencil of hairs; tufts of ochreous raised scales at base, under costal margin or in cell present in many species; ground colour of forewing from off-white, yellowish brown to dark grey or nearly black; costal margin often with three black spots of irregular shape; basal oblique black fascia as well as paired elongated spot in the middle and two black dots in the end of cell present in several species; subapical fascia usually indistinct; underside light brown, sometimes mottled with black (e.g., I. squamodorella , I. nigrosquamella ). Hindwing distinctly emarginated with moderately pointed apex, usually grey, sometimes brownish ( I. falkovitshi ); dorsal margin with black scales on both upper- and underside from base to half-length in the males of I. nigrosquamella , I. yemeniasquamella , I. squamodorella and I. nigrosquamella , the two last mentioned species with hair pencil on anal area in. Venation. In forewing Sc nearly to middle of costa; R1 from middle of cell, R2 from 5/6 of cell, R3 from base of R4-R5-M1 on common stalk, R4, R5 and M1from middle on common stalk to costa before apex (R4, R5) and to termen (M1); M3 and CuA1-CuA2 to termen; M3 connate with CuA 1 in end of cell; CuP absent; 1A+2A forked at base. In hindwing Sc to 2/3 of costa; Rs and M1 with long common stalk, R5 to costa before apex; M1-M3 and CuA1 to termen; CuA2 to dorsum; 1A+2A with short common stalk. Frenulum of female consisting of three acanthae, retinaculum row of raised scales at base of Sc and R. Frenulum of male simple, retinaculum a membranous hook under Sc near base (see also Clarke 1967: 217, pl. 108, fig. 1c).

Abdomen. Male abdominal tergites I–IV usually lighter than rest of abdominal tergites, yellowish rather than grey. Female abdominal tergites I–IV or I–V black in I. nigrosquamella , I. kyrgyzsquamella and I. yemeniasquamella . Male tergite and sternite VIII deeply separated laterally, tergite subtriangular with deep anteromedial emargination, distal portion from moderately broad tongue-shaped to narrow as an arrowhead, in some cases ( I. wachtlii , I. sattleri ) tergite VIII with three lobes of equal length and width paired basal coremata well developed. Sternite usually from 1.5 to 2.5 times broader than long, but some just slightly broader than long ( I. wachtlii ) or nearly three times broader than long ( I. falkovitshi ), anterior margin straight, posterior margin slightly sinuous; dense patches of hairs astride medial emargination, posteriolateral corners extending in short projections covered apically with short hairs. Female segment VII about two times the length of other abdominal segments. Sternite II in both sexes with pair of venulae with distinct apodemes.

Male genitalia. Uncus elongate (except for I. armatus ), straight or weakly curved ventrally, covered laterally with strong setae, apex usually pointed; gnathos long, stout, basal 3/4–4/5 strongly marginated with weakly sclerotized prolonged "window" inside, distal portion with a strong apically pointed hook ( I. squamodorella , I. nigrosquamella , I. lvovskyi and others) or weakly sclerotized, straight, tapered, sometimes serrated on the dorsal surface ( I. femoralis , I. sattleri ); tegumen either triangular with deep anterior emargination and broad lateral lobes ( I. myricariella , I. arenicolella , I. pseudomyricariella , I. brucinella , I. nilssoni , I. wachtlii , I. sattleri , I. kravchenkoi , I. armatus ) or boomerang-shaped with narrow parallel-sided lateral lobes ( I. squamodorella , I. nigrosquamella and others), sometimes apically strongly inflated ( I. kravchenkoi ); vinculum narrow band-shaped, posterior margin with weakly sclerotized lobe forming by merged, partially reduced juxta and sacculus; valva (cucullus) usually slightly shorter than phallus, straight or weakly curved, digitate, of moderate width, sometimes inflated apically ( I. wachtli , I. lvovskyi , I. sruogai ), or slender ( I. myricariella , I. arenicolella , I. brucinella ); saccus very short; phallus straight, tubular or tapered apically, sometimes obliquely cut from ¼ to apex on dorsal surface (see fig. 68 and Budashkin & Piskunov, 1990: 81, fig. 2a), without cornutus, ductus ejaculatorius long with coiled lamina.

Female genitalia. Apophyses posteriores very long, slender; apophyses anteriores moderately long, usually longer than segment VIII, straight, pointed; segment VIII subrectangular, tergite without modifications, evenly sclerotized, sternite weakly sclerotized, posterior margin slightly emarginated medially, anterior margin straight, sometimes with well-developed prolonged or rounded finely papillated lobes ( I. squamodorella , I. falkovitshi , I. piskunovi and others) that sometimes protrude beyond the anterior margin ( I. kyrgyzsquamella ); ostium surrounded with differently shaped sclerites: unpaired posterior sclerite sub-trapezoidal, rounded, drop-shaped, sometimes with prolonged lateral corners ( I. brucinella , I. pseudomyricariella ), anterolateral paired sclerite prolonged, leafshaped ( I. sattleri ), horn-shaped ( I. squamodorella , I. piskunovi , I. falkovitshi ), paired anterior sclerite narrow, digitate; subostial folds proceeding anteriorly from the posterior sclerite joining with anterolateral sclerites forming distinct lateral wall of ostium; subostial anterior sclerites forming entrance to the weakly sclerotized, funnel-shaped or tubular antrum; ductus bursae weakly sclerotized, sometimes finely spinulated ( I. kravchenkoi ), with group of large horn-shaped cornuti ( I. armatus ) or with small teeth ( I. sattleri ) in its posterior portion, usually long and narrow, gradually broadened before entrance of corpus bursae; corpus bursae rounded or ovate; signum a subhexagonal plate, margins slightly serrate, medial ridge narrow, often sinuous.

Relationships. The assignment of Istrianis to the tribe Litini, subfamily Gelechiinae is well documented ( Huemer & Karsholt 1999; Karsholt et al. 2013; Lee & Brown 2008a, b). Within Litini Istrianis is placed near Streyella Janse, 1958 . Aside from the homoplasious absence of lateral ocelli ( Lee & Brown 2008b) this is mainly supported by the genitalia. The integration of the saccular part of the valva with the juxta and vinculum is a common trend of transformation in the male genitalia in many genera of Litini (Ponomarenko 2005: 64). In Istrianis and Streyella this integration results in complete reduction of the sacculus that merges with the juxta in a single, weakly sclerotized flap on the posterior margin of the vinculum, whereas the cucullus remains more or less developed. We consider here this character as an apomorphy for the Istrianis + Streyella clade. Contrary to Istrianis and Streyella the juxta-vinculum-sacculus complex in related genera ( Pseudotelphusa Janse, 1958 , Carpatolechia Capuşe, 1964 , Teleiodes Sattler, 1960 ) is usually not so strongly fused, consisting of basally separated projections, whereas the cucullus is substituted by strongly sclerotized apically pointed glandiductors (Ponomarenko 2005:64). The male abdominal sternum VIII with prolonged posterolateral projections may be considered as another presumed apomorphy for the Istrianis + Streyella clade. It is likely that well developed ‘free flaps’ of sternum VIII and tergum VIII compensate for the reduced valva and their lost ability to grip the female ( Karsholt et al. 2013: 345). Istrianis can be separated from Streyella by the much longer cucullus ( Huemer & Karsholt 1999); moreover the cucullus in Istrianis is always digitate; it is never flattened as in most of Streyella species; the uncus and gnathos in Istrianis are distinctly elongate, whereas in Streyella species the uncus and gnathos are much shorter and broader. Istrianis differs additionally from Streyella in the clypeus with ventral margin truncate rather than rounded ( Lee & Brown 2008a), the absence of a group of sensilla trichodea on male abdominal sternite II and absence of a medial incision on the posterior margin of male tergite VIII that is usually present in Streyella species. The female genitalia of Istrianis differ from those of Streyella in the absence of a narrow medial subostial sclerite and absence of paired lateral sclerites at the entrance of the ductus bursae.

Istrianis is a rather homogeneous genus both superficially and in the genitalia. The Palaearctic species may be tentatively divided into two groups based mainly on the male genitalia. The first group comprises the species with subtriangular tegumen, with broad lateral arms, and the apex of the gnathos with small hook ( I. myricariella , I. arenicolella , I. pseudomyricariella , I. nilssoni , I. brucinella , I. wachtlii , I. sattleri , I. kravchenkoi , I. armatus ). Most of these species except for I. sattleri feed on Tamarix and the related Myricaria . The second group (rest of species) is characterized by the boomerang-shaped tegumen with narrow parallel-sided arms and the apex of the gnathos stout, with a strong hook in the male genitalia. The female genitalia of this group of species have well developed usually oxhorn-shaped anterolateral subostial sclerites and anterior lobes which are usually finely papillated or with foam-looking structure. The larvae of these species as far as known feed on Populus and Pistacia . In this group one can separate five species with black scales and/or hairs on the hindwing in the male ( I. squamodorella , I. nigrosquamella , I. kyrgyzsquamella , I. yemeniasquamella , I. finbosella ). The female of some of them may be recognized by black abdominal tergite I–V. The remaining species look rather uniform, except for I. wachtlii , I. femoralis and I. lvovskyi , and can be confused externally. Their identification must be based both on external and genitalia characters. This is especially true for I. myricariella and the closely related I. arenicolella , I. pseudomyricariella , I. nilssoni , I. kravchenkoi as well as for the following pairs of species: I. nigrosquamella and I. squamodorella ; I. piskunovi and I. falkovitshi and for some others. The shape of the male segment VIII may be used as an additional diagnostic character, but as far as we can judge it is rather variable.

We tentatively consider species from the second group as more advanced compared to the species from the first group, based on the genitalia characters. Therefore we place here species with a boomerang-shaped tegumen and narrow parallel-sided arms after species with subtriangular tegumen and broad lateral arms, well knowing that a better argued division of Istrianis into species groups should also be based on future studies the DNA.

Biology. Populus euphratica Oliv. , P. nigra L., ( Salicaceae ), Quercus floribunda Lindl. ex A. Camus (as ’ Quercus dilatata ’) ( Fagaceae ), Pistacia mutica Fish. & Mey , P. vera L. ( Anacardiaceae ), Tamarix species and Myricaria germanica (L.) ( Tamaricaceae ) are known as host plants for 10 of 17 Palaearctic species. Butea monosperma (Lam.) Taub. (= Butea frondosa Roxb. ) and Desmodium sp. ( Fabaceae ) are host plants of larvae for I. crauropa and I. steganotricha ( Meyrick, 1935) occurring in India and Java.

Larvae were observed feeding in and between young twigs or shoots of Myricaria germanica ( I. myricariella ) and Tamarix sp., within fruits and in shoots of Pistacia spp. ( I. femoralis ), between spun leaves of Populus euphratica ( I. lvovskyi ) and Quercus dilatata ( I. sattleri ) or producing galls on Tamarix ( I. brucinella ) ( Lvovsky & Piskunov, 1989; Budashkin & Piskunov, 1990; Huemer & Karsholt, 1999). The larva of I. femoralis was found in leaf galls caused by the aphid genus Forda Heyden, 1837 (Aphididae) (Budashkin & Piskunov 1990).

Larva and pupa are described for I. lvovskyi ( Lvovsky & Piskunov, 1989) .

The adults fly mainly during the warm season; they have, however, been observed from late February ( I. nigrosquamella ) to October–December ( I. brucinella ).

Distribution. In the Palaearctic region most species occur in arid semi-desert regions or in the regions with Mediterranean vegetation. Istrianis species occur from western Europe throughout Central Asia to Mongolia, and from central Europe through the Middle East to the Arabian Peninsula. Two species are known from India, and one of them also from Java. Actually only one species is recorded from southern Africa, but at least eight Afrotropical Istrianis species remain undescribed (Bidzilya, unpublished). Moreover several species currently associated with the Afrotropical genus Neotelphusa Janse, 1958 should be transferred to Istrianis (Bidzilya, unpublished).