Cotesia trivaliae Zikic & Shaw, 2024

Zikic, Vladimir, Mitrovic, Milana, Stankovic, Sasa S., Fernandez-Triana, Jose L., Lazarevic, Maja, van Achterberg, Kees, Marczak, Dawid, Milosevic, Marijana Ilic & Shaw, Mark R., 2024, An integrative taxonomic study of north temperate Cotesia Cameron (Hymenoptera, Braconidae, Microgastrinae) that form silken cocoon balls, with the description of a new species, Journal of Hymenoptera Research 97, pp. 255-276 : 255

Cotesia trivaliae Zikic & Shaw sp. nov.

Figs 5 , 6

Diagnosis.

The new species shares some morphological similarities with C. tibialis , including the shape of the first metasomal tergite (T1) laterally, with a medial keel near the proximal part, and the apical truncation of the hypopygium (features used by Nixon (1974) to characterise C. tibialis ). Additionally, the coloration of the legs, particularly the presence of a dark spot on the apical part of the otherwise reddish yellow hind femora, is similar to that described by Nixon (1974) for the early summer brood of his concept of C. tibialis , and there is a spine (albeit extremely weak) on the fifth segment of the fore tarsus. The ovipositor sheath is as short as in C. tibialis , and the aedeagus is similarly shaped in the two species. However, C. trivaliae sp. nov. can be clearly distinguished from C. tibialis based on the following characteristics: male antenna is completely brown in C. trivaliae sp. nov., while in C. tibialis 4-5 apical segments are yellowish. The length index of the 1st and the 2nd part of discoideus (1-CU1) / (2-CU1) of fore wings is about 0.7 in C. trivaliae sp. nov., relative to C. tibialis where this ratio is 0.8-0.9. Dorsally, (T1) length/width index ranges from 0.9 to 1.1 in C. trivaliae sp. nov., while it is 1.2-1.3 in C. tibialis . Communal cocoons in C. trivaliae sp. nov. are spun differently from those of C. tibialis , also C. ofella . In C. tibialis and C. ofella (Fig. 6D-F ), they are fluffy to varying degrees, and individual cocoons are not visible because they are covered with very densely spun communal silk. Consequently, the structure appears as a ball mass 15-25 mm in length and about 10 mm in width. Cocoon masses of C. trivaliae sp. nov. are more oblong, usually 10-15 mm long and 5-6 mm wide, and much less fluffy, with at least some individual cocoons visible through sparsely spun silk. The average genetic distance revealed above between C. trivaliae sp. nov. and other morphologically similar taxa indicates that it is a different species. The only known host of C. trivaliae sp. nov. is Orthosia gracilis , substantially different from the known hosts of the close taxa, although it must have other as yet undiscovered hosts to enable it to complete its annual cycle.

Type material.

Holotype: Poland ♀; Kampinos National Park, Granica; 05.VI.2018; ex cocoon mass in grassland; V. Žikić leg.; dry mounted. Paratypes: Poland 41 ♀ 29 ♂; Kampinos National Park, Granica; 05.VI.2018; ex same brood (3 ♀ 3 ♂ dry mounted, 3 ♀ 3 ♂ microscopic slide mounted, 1 ♀ barcoded, the rest kept 34 ♀ 23 ♂ in 96% alcohol); Poland 40 ♂; Kampinos National Park, Granica, 05.VI.2018, (1 ♂ barcoded, 3 ♂ dry mounted, 1 ♂ microscopic slide mounted, 35 ♂ in 96% alcohol); "same data as for preceding" 15 ♀ 12 ♂ (1 ♀ barcoded, 3 ♀ 3 ♂ dry mounted, 3 ♀ 1 ♂ microscopic slide mounted, 8 ♀ 8 ♂ in 96% alcohol); "same data as for preceding" 54 ♀ 6 ♂ (1 ♀ barcoded, 3 ♀ 3 ♂ dry mounted, 3 ♀ 1 ♂ microscopic slide mounted, the rest kept in 96% alcohol); V. Žikić leg; Slovenia 1 ♀; Ljubljana; ex Orthosia sp.; 01.VI.2018; Š. Modic leg.; (1 ♀ barcoded, slide mounted); Great Britain 28 ♀ 16 ♂ Scotland, Berwickshire, Foulden ex Orthosia gracilis , collected 10.VI.2017, (17 ♀ 5 ♂ barcoded; 8 ♀ 11 ♂ barcoded; 3 ♀ from a further brood of low emergence; VII.2017; M. R. Shaw leg.; Great Britain 1 ♀ 1 ♂; Scotland, Fife, Fleecefauld, ex O. gracilis collected 14.VII.2012, emerged 04.VIII.2012 (1 ♀ 1 ♂ barcoded); M. R. Shaw leg.; Great Britain 3♀; England, Kent, Swanscombe, ex cocoon mass collected on Phragmites australis 10.IV.2017, emerged 02.V.2017 (3♀ barcoded) M. Jennings leg.

Depositories.

The holotype ♀ of C. trivaliae sp. nov., and paratypes have been deposited in the collection of the Faculty of Sciences and Mathematics, the University of Niš, Serbia. A single female from Slovenia has been deposited in the collection of the Faculty of Sciences and Mathematics, the University of Niš, Serbia. Additionally, 3 ♀ 3 ♂ from Poland, as well as all specimens from Great Britain have been deposited at the Department of Natural Sciences, National Museums of Scotland.

Etymology.

The new species is named in honour of the gothic rock band Trivalia .

Distribution.

The currently known distribution of the new species is Poland, Slovenia and the UK (England and Scotland).

Description.

Female: (Fig. 5 ). Body length 2.6 mm (range 2.5-2.7 mm) (Fig. 5A ).

Head: In frontal view (Fig. 5B ), about 1.6 times as wide as long (from widest eye to eye), temple about 0.9 times as long as eye at first narrowing behind roundly, ocelli in moderately low triangle (Fig. 5D ), diameter between anterior/posterior ocelli and between posterior ocelli 0.5. Index of intertentorial distance/tentori-ocular distance = 2.7. Face above clypeus smooth, while below antennal sockets sculptured. Stemmaticum and vertex smooth. Antennae (Fig. 5N ) as long as body, 1st flagellar segment as long as 2nd, penultimate segment 2.2 times shorter than 1st, length/width of penultimate segment = 1.1, last segment 1.4 times longer than penultimate, pointed at apex.

Mesosoma: Mesoscutum in dorsal view (Fig. 5G ) punctate, middle part slightly rugose, prescutellar sulcus deep, with 9 foveae. Scutellum smooth and shiny, with about thirty punctures. Propodeum (Fig. 5K ) strongly rugose, median keel completely developed. Mesopleuron (Fig. 5C ) in larger part shiny, marginally sculptured bearing dense setae, mid-mesoscutal line large with 24-25 deep punctures. Metapleuron rugose, small lower area smooth and shiny.

Legs: Fore leg spine on 5th tarsomere present, extremely weak; hard to see (Fig. 5L ). Hind leg (Fig. 5M ) with femur 3.9 times as long as wide, tibial spurs subequal, inner spur not reaching middle of hind basitarsus.

Wings: Fore wing length 2.5 mm (range 2.4-2.5 mm), and 2.5 times as long as wide at maximal distances (Fig. 5E ), pterostigma 2.2 times longer than wide, metacarp (1-R1) about as long as pterostigma, 1st part of discoideus (1-CU1) about 0.7 times as long as 2nd (2-CU1), vein (cu-a) 0.4 times as short as (CU1), with posterior third bent forward. Hind wing 4.3 times as long as wide at maximal distances, vannal lobe straight without setae in mid part (Fig. 5F ).

Metasoma: In dorsal aspect T1 heavily rugose all over, widened behind (Fig. 5J ), almost as long as wide, in profile T1 bearing conspicuous short medial keel (Fig. 5C ). Second tergite (T2) rectangular, 0.4-0.5 times as long as wide, sculptured, posterior margin crenulate (Fig. 5J ). Third tergite (T3) almost equal to second, smooth, shiny, slightly sculptured at mid base, bearing sparsely distributed hairs practically in a single row (Fig. 5J ). Hypopygium in lateral view short, truncate at apex (Fig. 5I ). Last tergite in line with apex of hypopygium (Fig. 5I ). Ovipositor sheath short (Fig. 5H ).

Colour: Head, mesosoma including tegula, all coxae and metasoma black. Trochanter brownish, rest of leg parts yellowish; hind femora apically with small dark spot. Antennae brown. Palpi yellow. Wing venation distinctly yellowish to brown, metacarp, pterostigma and radialis brown.

Male: (Fig. 6 A-C ). Morphology and colouration (Fig. 6A ) similar to female except for sexual characters. All antennal segments (Fig. 6B ) brown, antenna about 1.2 times as long as body. Aedeagus (Fig. 6C ) with two-toothed digiti at apex, teeth well developed, relatively large and sharp, digitus length/width ratio = 2.1, digitus 2.8 times as short as volsella, cuspis inconspicuous.

Cocoon mass: (Fig. 6D ). Relatively small, usually elongated, 10-15 mm long, and about 5-6 mm wide, weakly fluffy, communal silk sparsely spun over individual cocoons leaving them partly visible, light-yellow coloured.

Figures

Figure 5. Cotesia trivaliae sp. nov. female A habitus B head frontal view C mesosoma and T 1 lateral view D head dorsal view E fore wing F hind wing G mesoscutum dorsal view H ovipositor lateral view I metasoma lateral view J metasoma dorsal view (T 1 - T 3) K propodeum dorsal view L 5 th tarsomere of front leg, arrow points spine M hind leg outer face N antenna. Scale bars: 500 µm (A-K, M, N); 100 µm (L).

Figure 6. Cotesia trivaliae sp. nov., male (A-C) A habitus B antenna C aedeagus ventral view; cocoon masses (D-F) D C. trivaliae sp. nov. E C. tibialis F C. ofella. Scale bars: 500 µm (A, B); 100 µm (C).