Eocenhecabolus Belokobylskij, 2023

Belokobylskij, Sergey A., Simutnik, Serguei A., Vasilenko, Dmitry V. & Perkovsky, Evgeny E., 2023, First record of the parasitoid subfamily Doryctinae (Hymenoptera, Braconidae) in Rovno amber: description of a new genus and species with stigma-like enlargement on the hind wing of the male, Journal of Hymenoptera Research 95, pp. 59-72 : 59

Genus Eocenhecabolus Belokobylskij gen. nov.

Type species.

Eocenhecabolus kotenkoi Belokobylskij, gen. et sp. nov., by present designation and monotypy.

Etymology.

Named after “Eocene” from the geological epoch dated to the Rovno amber and the generic name of its extant type genus Hecabolus of the tribe Hecabolini from subfamily Doryctinae . Gender: masculine.

Description.

Head (Fig. 1E, F, H ) not depressed, weakly transverse. Ocelli medium-sized, weakly convex, arranged in triangle with base 1.3 times its sides. Frons almost not convex, without lateral protuberances. Eyes large, oval, glabrous. Face distinctly convex. Malar suture present, but weak. Clypeus relatively high, with distinct lower visor. Clypeal suture fine laterally, absent on wide distance dorsally. Anterior tentorial pits small. Occipital carina present and distinct at least laterally and dorsally. Mandibles robust. Maxillary palpus medial length. Antenna (Fig. 1C, E, H ) mostly missing, only four segments present. Scape short and wide, approximately as long as maximum width. Pedicel relatively short and thick, about as long as scape. First flagellomere long, subcylindrical, weakly curved and without any modifications. Mesosoma (Fig. 1C, G ) not depressed. Pronotum convex in posterior half, with distinct short longitudinal lateral carinae. Sides of pronotum mainly smooth with short rugae on oblique furrow. Mesoscutum distinctly (but not highly) roundly convex above pronotum, densely and rather distinctly granulate-punctate. Notauli present, deep and complete, reaching prescutellar furrow. Scutellum convex. Prepectal carina present, distinct. Mesopleuron mainly smooth. Precoxal sulcus present, but short (not more than half of mesopleuron length below), rather deep, almost straight, finely crenulate. Metascutum without dorsal tooth (lateral view). Propodeum evenly curved in lateral view, with areas delineated but distinct carinae, with wide, sub-round and smooth basolateral areas, with narrow and long areola, distinctly separated petiolate area and relatively short basomedial carina; without lateral tubercles; propodeal spiracle subcircular. Wings (Figs 1A, B , 2A ). Fore wing relatively wide, evenly faintly infuscate; pterostigma rather long and wide. Radial (marginal) cell not shortened, closed distally, wide, about 3.5 times longer than its maximum width. Metacarp (1-R1) 1.2 times longer than pterostigma. Radial vein (r) arising weakly before middle of pterostigma. First medial abscissa (1-SR+M) present and weakly sinuate. Both radiomedial veins (2-SR and r-m) present. Second radiomedial (submarginal) cell relatively long, pentagonal. Discoidal (first discal) cell petiolate anteriorly; petiole (1-SR) short. Recurrent vein (m-cu) distinctly postfurcal, weakly convergent posteriorly with basal vein (1-M). First mediocubital vein (M+CU1) well sclerotised and straight. Nervulus (cu-a) distinctly postfurcal. Brachial (first subdiscal) cell open posteriorly; brachial vein (CU1b) absent. Transverse anal veins (2A and a) absent. Hind wing. Second abscissa of costal vein (1-SC+R) with elementary elliptic stigma-like enlargement. Radial vein (SR) unsclerotised and transparent. Nervellus (cu-a) present. Submedial (subbasal) cell large. First abscissa of mediocubital vein (M+CU) more than twice longer than second abscissa (1-M). Legs (Figs 1C, D , 2B ) rather robust and short. Fore tibia with distinct spines arranged almost in single line. Hind coxa elongate, without ventro-basal tubercle and corner, weakly shorter than propodeum. Hind femur short and wide, 0.7 times as long as hind tibia. Hind tibia weakly thickened distally, with at least two distinctly visible spines on its dorsal margin in distal quarter. Hind tibial spur glabrous, relatively short, about 0.3 times as long as hind basitarsus. Hind basitarsus short, about half as long as second to fifth segments combined. Tarsal claw medium size, simple and evenly curved. Metasoma (Figs 1C, D, G , 2B ) elongate, oval in dissection, not pressed, segments behind third one distinctly exposed posteriorly. First metasomal tergite not wide, weakly widened distally, with deep dorsope, with distinct dorsomedial carinae situated closed to each other, with distinct lateral carinae, striate medially and smooth laterally, with spiracles situated on basal third of tergite, spiracular tubercles small, weakly shorter that second and third tergites combined. Suture between second and third tergites absent. Second tergite mainly smooth, with shallow and short sublateral depression. Laterotergites (epipleura) of segments behind first one perhaps not separated; spiracles placed on the lateral part of tergites. Genitalia distinctly visible from below.

Comparative diagnosis.

This new genus belongs to the tribe Hecabolini based on the fore wing with a distally open brachial (subdiscal) cell and the hind wing of male with an elementary stigma-like enlargement. The latter character is similar to that found in the extant doryctine genera Hemidoryctes Belokobylskij, 1992, Dendrosoter Wesmael, 1838, Bracocesa Koçak & Kemal, 2008, and Doryctophasmus Enderlein, 1912.

Eocenhecabolus gen. nov. is most similar to the Pantropical Hemidoryctes Belokobylskij from the subtribe Stenocorsina ( Doryctinae : Hecabolini ) by the wing venation and analogous enlargement on the hind wing. However, the new genus differs from Hemidoryctes by the very short antennal scape, approximately as long as its maximum width (elongated, about 1.5 times longer than the maximum width of that in Hemidoryctes ), the enlarged pedicel, about as long as the scape (not enlarged and only about 0.5 times as long as the scape in Hemidoryctes ), the mostly smooth temple with additional sparse punctuation (densely granulate-striate in Hemidoryctes ), the mostly smooth side of the mesosoma (basically densely granulate in Hemidoryctes ), the propodeum with areas delineated by distinct carinae (without areas delineated by carinae in Hemidoryctes ), the fore wing not maculate, but only faintly infuscate (distinctly maculate in Hemidoryctes ), the distinctly postfurcal recurrent vein (m-cu) of the fore wing (usually distinctly antefurcal in Hemidoryctes ), the relatively short discoidal (discal) cell of the fore wing (distinctly elongate in Hemidoryctes ), the weakly postfurcal nervulus (cu-a) in the fore wing (strongly postfurcal in Hemidoryctes ), the first abscissa of the mediocubital vein (M+CU) of the hind wing distinctly longer than the second abscissa (1-M) (distinctly shorter in Hemidoryctes ), the smooth and less thick hind femur, 3.0 times longer than its maximum width (densely granulate-reticulate and thicker, 2.5 times longer in Hemidoryctes ), the hind tibia with relatively long setae and at least two distinct spines on its dorsal margin (with very short setae and without spines on the dorsal margin in Hemidoryctes ), the shortened hind tarsus with the segment not narrowed toward its distal margin (elongate and segments distinctly narrowed distally in Hemidoryctes ), and the smooth metasoma behind the first tergite (the second and part of third tergites heavily sculptured in Hemidoryctes ).

Apart from several individual differences, the new genus differs from other three extant genera exhibiting stigma like enlargement on hind wing ( Dendrosoter Wesmael, Bracocesa Koçak & Kemal and Doryctophasmus Enderlein) in having the open distally brachial (first subdiscal) cell and no brachial vein (CU1b) in the fore wing (this cell closed distally and the brachial vein present in all latter genera), and large submedial (subbasal) cell in the hind wing with the first abscissa of the mediocubital vein (M+CU) distinctly longer than the second abscissa (1-M) (this cell small and the first abscissa short in all three latter genera).

Among known fossil Doryctinae genera, Eocenhecabolus gen. nov. is superficially similar to the extinct Doryctomorpha tertiaria Brues, 1933 described based on a female from Baltic amber (Brues, 1933). However, the assignment of this species to the peculiar endemic New Zealand genus Doryctomorpha Ashmead, 1900 from the subfamily Mesostoinae is very doubtful and unsupported by known morphological characters. The female of D. tertiaria Brues perhaps may belong to the new genus described here, but absence of important information in this species description (especially regarding wing venation and legs) and uninformative figure together with the loss of the type specimen prevent us to form a reliable opinion about its placement. Anyway, Eocenhecabolus kotenkoi gen. et sp. nov. differs from D. tertiaria Brues by having the head transverse in dorsal view, with a transverse diameter of eye 1.5 times longer than the temple (head subquadrate and with a transverse diameter of eye 2.0 times longer than the temple in D. tertiaria ), the vertex transversely and sinuately striate (smooth in D. tertiaria ), the propodeum with areas distinctly delineated by carinae (without areolation in D. tertiaria ), and the hind coxa suboval and without a prominent lower corner (subtriangular and with a prominent lower corner in D. tertiaria ).

Figures

Figure 1. Eocenhecabolus kotenkoi gen. et sp. nov. (male, holotype, Rovno amber, # SIZK VT- 607) A habitus, right dorso-lateral view B habitus, left ventro-lateral view C body, lateral view D body, ventro-lateral view E head and antenna, fronto-lateral view F head, dorsal view G propodeum and metasoma, dorsal view H head and antenna, lateral view.

Figure 2. Eocenhecabolus kotenkoi gen. et sp. nov. (male, holotype, Rovno amber, # SIZK VT- 607) A wings B metasoma and hind leg, lateral view.