Palaeorhoptrocentrus Belokobylskij, 2023

Belokobylskij, Sergey A. & Manukyan, Andranik R., 2023, Doryctinae (Hymenoptera, Braconidae) from Baltic amber: description of a new genus and species, Zootaxa 5249 (5), pp. 577-584 : 578-583

Genus Palaeorhoptrocentrus Belokobylskij , gen. nov.

http://zoobank.org/ C598560B-3F0D-4DB7-A70E-C283E96DA010

Type species. Palaeorhoptrocentrus kanti Belokobylskij , gen. et sp. nov., by present designation.

Etymology. Named after “Palaeo” (Greek for “ancient”) and the generic name of similar extant genus Rhoptrocentrus from the tribe Doryctini (Doryctinae) . Gender: masculine.

Description. Head ( Figs 1C, D ; 2C, D ) not depressed, transverse. Vertex with rather distinct low and wide transverse crest. Ocelli medium-sized, distinctly convex, arranged in obtuse triangle. Frons flat, without lateral protuberances. Eyes large, oval, glabrous. Temple (dorsal view) convex, much shorter than transverse diameter of eye. Face distinctly convex. Malar space rather short. Hypoclypeal depression present. Occipital carina distinct dorsally and laterally. Mandibles relatively short and narrow. Maxillary palpus long and slender, perhaps with 6 segments.

Antenna ( Figs 1A, C, F ; 2A, D ) slender, filiform, with 21–24 antennomeres, about 1.2 × longer than body. Scape short and relatively narrow, without transformations, 1.7 × longer than its maximum width. Pedicel long and rather thick, 1.3 × longer than scape. First flagellomere long, weakly depressed and widened, weakly curved. Second flagellomere subcylindrical, straight, relatively long, almost as long as third flagellomere. Penultimate flagellomere slender, almost as long as apical flagellomere; the latter weakly acuminate.

Mesosoma ( Figs 1B, D ; 2C, D ) not depressed, long. Pronotal neck short. Side of pronotum with distinct, narrow, oblique and curved submedial furrow, delineated upper and below by distinct carinae and with crenulation; remaining part of pronotum smooth or with sparse rugosity. Mesoscutum distinctly roundly convex above pronotum, distinctly densely granulate-reticulate. Notauli complete, deep anteriorly and shallow posteriorly, fused posteriorly and reaching prescutellar furrow. Prescutellar furrow narrow medially and weakly widened laterally, with high medial carina, smooth to weakly reticulate at most part. Scutellum convex. Prepectal carina present. Mesopleuron mainly smooth. Precoxal sulcus present, relatively short (about half of mesopleuron length below), deep, very weakly curved, smooth. Metascutum perhaps without dorsal tooth (lateral view). Metapleuron almost smooth anteriorly and rugulose posteriorly. Propodeum evenly curved towards backside (lateral view), with areas delineated but distinct carinae; basolateral area not long and mainly rugulose, areola relative short and not wide, petiolate area short and separated by distinct carina; lateral tubercles absent.

Wings ( Figs 1G, H ; 2H ). Fore wing wide, hyaline; pterostigma rather long and relatively wide. Radial (marginal) cell not shortened, closed distally, wide, 3.0 × longer than its maximum width. Metacarp (1-R1) about 1.1 × longer than pterostigma. Radial vein (r) arising before middle of pterostigma. First medial abscissa (1-SR+M) present and very weakly curved. Both radiomedial veins (2-SR and r-m) present. Second radiomedial (submarginal) cell relatively long and pentagonal. Discoidal (first discal) cell petiolate anteriorly; petiole (1-SR) relatively short. Recurrent vein (m-cu) 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 narrow and closed posteriorly; brachial vein (CU1b) present and long. Parallel vein (CU1a) not interstitial, arising from distal margin of brachial (subdiscal) cell distinctly behind its middle, from anterior third (3-CU1 shorter than CU1b). Transverse anal veins (2A and a) absent. Hind wing. Second abscissa of costal vein (1-SC+R) 2.5 × longer than first abscissa (C+SC+R). Radial vein (SR) spectral. Nervellus (cu-a) present. Submedial (subbasal) cell short. First abscissa of mediocubital vein (M+CU) almost half as long as second and third abscissae combined (1-M). Recurrent vein (m-cu) distinctly antefurcal.

Legs ( Figs 1B, E ; 2B, G ) relatively robust and long. Fore tibia with spines arranged almost in single line. Hind coxa elongate, suboval, without ventro-basal tubercle and corner, almost as long as propodeum. Hind femur rather long and wide, about 0.7 × as long as hind tibia. Hind tibia weakly thickened distally, without any visible spines on its dorsal margin. Hind tibial spur short, about 0.3 × as long as hind basitarsus. Hind basitarsus elongate, 0.6 × as long as second–fifth segments combined. Tarsal claw medium size, simple and evenly curved.

Metasoma ( Figs 1B, E ; 2B, E, F, G ) elongate, oval in cross-section, not depressed, segments behind third one distinctly exposed posteriorly. First metasomal tergite wide, strongly and sharply widened basally and then distinctly evenly widened towards posterior margin of tergite, with dorsope, with distinct dorsomedial carinae situated closed to each other and convergent posteriorly, with distinct lateral carinae, entirely distinctly striate, without visible spiracular tubercles, almost as long as second and third tergites combined. Suture between second and third tergites absent. Second tergite mainly smooth, but striate in basal quarter or third, without sublateral depression. Laterotergites (epipleura) of segments behind first one not separated, but perhaps second tergite with separate laterotergites at least in basal third to half; spiraculars placed on lateral part of tergites. Ovipositor shorter than metasoma, ventrally serrate in apex.

Comparative diagnosis. The new genus Palaeorhoptrocentrus gen. nov. probably belong to the tribe Doryctini based on the fore wing venation and morphological characters of the head, meso- and metasoma. The postfurcal position of recurrent vein (m-cu) and not interstitial position of parallel vein (CU1a), together with absence of basoventral corner and tubercle on the hind coxa are known only in a few extant doryctine genera, but this new genus is most similar to Dendrosotinus Telenga, 1941 , Guaygata Marsh, 1993 , and Rhoptrocentrus Marshall, 1897 .

The new fossil genus differs from Dendrosotinus Telenga (especially from its type species D. ferrugineus (Marshall, 1890)) by having the pro- and mesopleura mainly smooth (widely reticulate-areolate in Dendrosotinus ), propodeum with several areas distinctly delineated by carinae (without such areas in Dendrosotinus ), parallel vein (CU1a) arising from distal margin of the brachial (subdiscal) cell in its anterior third (interstitial to medial vein (2CU1) in Dendrosotinus ), first abscissa of mediocubital vein (M+CU) almost half as long as the second and third abscissae combined (1-M) (almost equal to second and third abscissae (1-M) in Dendrosotinus ), recurrent vein (mcu) of hind wing strongly antefurcal (subinterstitial in Dendrosotinus ), pterostigma entirely brown (brown medially and yellowish basally and apically in Dendrosotinus ), first metasomal tergite strongly and sharply widened basally and then distinctly evenly widened towards posterior margin (only evenly widened from base towards its posterior margin in Dendrosotinus ), suture between second and third tergites absent (present but relatively fine in Dendrosotinus ), second metasomal tergite mainly smooth, only striate in basal quarter or third, third tergite entirely smooth (second tergite entirely striate-reticulate, third tergite striate-reticulate at least in basal half in Dendrosotinus ), and laterotergites of segments behind first one not separated (distinctly separated on second and third tergites in Dendrosotinus ).

Palaeorhoptrocentrus gen. nov. differs from Guaygata Marsh by having the vertex with rather distinct low and wide transverse crest (without such crest in Guaygata ), the first flagellomere weakly depressed, widened and weakly curved, almost as long as second flagellomere (subcylindrical, not depressed and not curved, distinctly longer than second flagellomere in Guaygata ), pro- and mesopleura mainly smooth (almost entirely reticulate-granulate in Guaygata ), hind coxa without basoventral corner and tubercle (with such corner and distinct tubercle in Guaygata ), radial vein (r) arising distinctly before middle of pterostigma (usually from middle of pterostigma in Guaygata ), recurrent (m-cu) and basal (1-M) veins convergent posteriorly (subparallel in Guaygata ), recurrent vein (m-cu) of hind wing strongly antefurcal (subinterstitial in Guaygata ), and hind femur smooth (densely reticulate-granulate in Guaygata ).

Palaeorhoptrocentrus gen. nov. differs from Rhoptrocentrus Marshall by having the vertex with rather distinct low and wide transverse crest (without such crest in Rhoptrocentrus ), first flagellomere weakly depressed, widened and weakly curved, almost as long as the second flagellomere (subcylindrical, not depressed, widened or curved, longer than second flagellomere in Rhoptrocentrus ), pro- and mesopleura mainly smooth, precoxal suture smooth (widely rugose-reticulate, precoxal suture widely sculptured in Rhoptrocentrus ), fore wing hyaline (distinctly infuscate in Rhoptrocentrus ), recurrent vein (m-cu) of fore wing weakly postfurcal (distinctly postfurcal in Rhoptrocentrus ), parallel vein (CU1a) arising from distal margin of brachial (subdiscal) cell in its anterior third (3-CU1 distinctly shorter than CU1b) (arising from the middle of distal margin of brachial (subdiscal) cell, 3-CU1 equal to CU1b in Rhoptrocentrus ), recurrent vein (m-cu) of hind wing strongly antefurcal (subinterstitial in Rhoptrocentrus ), hind femur smooth (densely and coarsely punctate in Rhoptrocentrus ), and ovipositor shorter than metasoma (about twice longer than metasoma in Rhoptrocentrus ).

Among known fossil Doryctinae taxa Palaeorhoptrocentrus gen. nov. is the most similar to the extinct Doryctomorpha tertiaria Brues, 1933 described from a female from Baltic amber ( Brues, 1933). However, the assignment of the latter species to the endemic New Zealand genus Doryctomorpha Ashmead, 1900 from the subfamily Mesostoinae is very doubtful and unsupported by known morphological characters. According to the available description of this species, we consider that the D. tertiaria Brues belongs actually to Palaeorhoptrocentrus gen. nov. with the new combination P. tertiaria ( Brues, 1933) , comb. nov.

However, P. kanti differs from P. tertiaria (Brues) by having the head transverse (quadrate in P. tertiaria ), vertex densely transversely striate (smooth in P. tertiaria ), antenna filiform and less slender (setiform and “extremely slender” in P. tertiaria ), scape distinctly longer than pedicel (almost equal in the length in P. tertiaria ), the first flagellomere widened, about 4.0 × longer than its maximum width, almost as long as the second flagellomere (not widened, about 6.0 × longer than its maximum width, longer than the second flagellomere in P. tertiaria ), notauli not strongly expressed (strongly expressed in P. tertiaria ), propodeum areolate, with areas distinctly delineated by carinae (not areolate in P. tertiaria ), metasoma without suture between second and third tergites (with very fine transverse suture in P. tertiaria ), and ovipositor sheath shorter than metasoma (as long as or slightly longer than metasoma in P. tertiaria ).

Key to species of the genus Palaeorhoptrocentrus gen. nov.

1. Vertex densely transversely striate. Antenna filiform, relatively thick; scape distinctly longer than pedicel. First flagellomere widened, about 4.0 × longer than its maximum width, almost as long as second flagellomere. Propodeum with areas distinctly delineated by carinae. Metasoma without visible suture between second and third tergites. Ovipositor sheath distinctly shorter than metasoma. Body length 2.0– 2.3 mm ...................................................... P. kanti sp. nov.

- Vertex smooth. Antenna setiform, extremely slender; scape about equal to pedicel. First flagellomere not widened, about 6.0 × longer than its maximum width, longer than second flagellomere. Propodeum without areas delineated by carinae. Metasoma with visible but fine suture between second and third tergites. Ovipositor sheath as long as or slightly longer than metasoma. Body length 2.2–2.5 mm ........................................................ P. tertiaria (Brues) , comb. nov.

Figures

FIGURE 1. Palaeorhoptrocentrus kanti gen. et sp. nov. (holotype, female, Baltic amber, BX 54/22) (A) Habitus, lateral view. (B) Body (head, mesosoma and metasoma), lateral view. (C) Head and basal antennomeres of antenna, lateral view. (D) Head and mesosoma, lateral view. (E) Propodeum, metasoma and ovipositor, lateral view. (F) Apical antennomeres of antenna. (G) Wings. (H) Medial part of fore wing.

FIGURE 2. Palaeorhoptrocentrus kanti gen. et sp. nov. (paratype, female, Baltic amber, BX 54/22) (A) Habitus, dorsal view. (B) Habitus, lateral view. (C) Head and mesosoma, dorsal view. (D) Head and mesosoma, lateral view. (E) Propodeum and basal half of metasoma, dorsal view. (F) Metasoma, dorsal view. (G) Metasoma and ovipositor, lateral view. (H) Fore wing.