Protoctonus Davidian, 2022

Davidian, Elena M., Manukyan, Andranik R. & Belokobylskij, Sergey A., 2022, A new genus and species of the aphid parasitoids (Hymenoptera: Braconidae Aphidiinae) from Baltic amber, Zootaxa 5165 (4), pp. 520-526 : 521-525

Genus Protoctonus Davidian , gen. nov.

Type species Protoctonus groehni Davidian , sp. nov.

Etymology. The new genus name is composed from the Greece word “protos” (= first, pioneering) and part of the related aphidiine genus name “ Monoctonus ”. The gender is masculine.

Diagnosis. Mandible bidentate; maxillary palpus 4-segmented, labial palpus 3-segmented ( Fig. 1C ). Antenna ( Fig. 1D ) with 11 antennomeres, widened toward apex, densely pubescent. Mesoscutum with notauli reaching its middle ( Fig. 1E ). Propodeum perhaps with median areola delineated by weak carinae. In fore wing ( Figs 1G, H ; 2A ) pterostigma triangular. Metacarp (1-R1), radial (r, 3-SR, SR1) and parallel (CU1a) veins of fore wing long and almost reaching distal margin of wing; medial (1-SR+M, 2-M, 3-M) vein short and not reaching distal margin of wing. First and second radiomedial (submarginal) cells fused together with discoidal (discal) cell and formed united large central cell. Also present closed medial (basal), submedial (subbasal) and brachial (subdiscal) cells. Hind wing without closed cells. Legs ( Figs 1A, F ) covered by dense and semi-erect setae (as those on body). Petiole of metasoma ( Fig. 1F ) rather long, slightly widened towards apex, about 1.6 × longer than its width medially at level of spiracles. Ovipositor sheaths ( Figs 1F ; 2B ) not long, weakly curved down, acuminate, 2.6 × longer than its maximum width, 0.15 × as long as metasoma, gradually tapered from base towards apex, narrowly rounded apically, with long setae on dorsal and ventral margins; setae apically short.

Remarks. The new aphidiine genus Protoctonus gen. nov. is most similar to the fossil genera Protacanthoides Mackauer, 1961 (with type species Trioxys obscuriformis Quilis, 1940 = Trioxys fossilis Mackauer, 1959 ), Promonoctonia Stary, 1973 (with type species Aphidius quievreuxi Quilis, 1940 ), and Sakhalinoctonus Davidian, 2021 (with type species Sakhalinoctonus alexrasnitsyni Davidian, 2021) by the fewer number of antennomeres, presence the closed central cell in fore wing and curved downwards and taped apically ovipositor sheaths.

Genera Protacanthoides and Promonoctonia are characterised by a 13 antennomeres in thick antenna, short and not reaching distal margin of the wing the metacarp (1-R1), radial (r, 3-SR, SR1) and medial (2-M, 3-M) veins, and curved down the ovipositor sheaths. Besides those, Protacanthoides fossilis has metasomal petiole short, smooth and without protruding spiracular tubercles, length of petiole approximately equal to its maximum width; ovipositor sheath evenly curved downwards, strongly tapered towards its apex and acuminate apically, about 0.15 × as long as metasoma. Unfortunately the information about condition of notauli and propodeum and pubescence of the ovipositor sheath are absent in the description of this species.

Promonoctonia quievreuxi is additionally characterised by the following features: notauli missing; propodeum smooth and without delineated areola; metasomal petiole very short and wide; ovipositor sheaths claw-shaped, with long and wide its basal part and short and narrow apical part, approximately 3.0 × longer than its maximum width and 0.15 × as long as metasoma.

The genus Sakhalinoctonus has 12 antennomeres; relatively long radial (r, 3-SR, SR1) and medial (2-M, 3-M) veins, which do not reach the distal margin of fore wing; ovipositor sheath long, almost 6.0 × longer than its maximum width, weakly curved down and gradually tapered towards apex, very narrowly rounded apically, and covered by mainly long setae.

The differences between Protoctonus gen. nov. and similar fossil genera are given in the key below.

1. Antenna with 11 antennomeres ( Fig. 1D )—Flagellomeres from fifth moniliform ( Fig. 1D ). Metacarp (1-R1) of fore wing 1.3 × longer than pterostigma. Radial (r, 3-SR, SR1) vein and metacarp (1-R1) almost reaching distal margin of fore wing ( Fig. 1G, H ; 2A ). Ovipositor sheaths ( Figs 1F ; 2B ) curved downwards, subtriangular in shape, taped towards apex, entirely covered by dense setae: long setae arranged along dorsal and ventral margins and short setae located on apex of sheaths. Ovipositor sheath 2.6 × longer than its maximum basal width. Baltic amber..................................... Protoctonus gen. nov.

- Antenna with 12–13 antennomeres....................................................................... 2

2. Antenna with 12 antennomeres, relatively slender. Metacarp (1-R1), radial (r, 3-SR, SR1) and medial (2 М, 3-M) veins of fore wing long and almost reaching distal margin of wing. Ovipositor sheath relatively long, curved down, gradually tapered towards apex, narrow curved apically, about 6.0 × longer than its maximum width and 0.4 × as long as metasoma. Sakhalinian amber........................................................................... Sakhalinoctonus Davidian

- Antenna with 13 antennomeres, thick. Metacarp (1-R1), radial (r, 3-SR, SR1) and medial (2 М, 3-M) veins of fore wing short and far not reaching distal margin of wing. Ovipositor sheaths short, claw-shaped, with long widened basal part and short narrow apical part, or evenly tapered to apex and acuminate apically, about 3.0 × longer than its maximum width and 0.15–0.20 × as long as metasoma.................................................................................. 3

3. Ovipositor sheaths claw-shaped, with long and wide their basal part and short and narrow apically, perhaps narrowly rounded apically.—Mesoscutum without notauli. Propodeum without delineated areola. Petiole of metasoma very short and wide. France, Haut-Rhin, potassium layers...................................................... Promonoctonia Starý

- Ovipositor sheaths weakly curved downwards, gradually tapered from base to apex and acuminate apically.—Petiole of metasoma subtriangular, smooth, without projecting spiracular tubercles, about as long as its maximum width. France, Haut-Rhin, potassium layers................................................................. Protacanthoides Mackauer

Key to Protoctonus gen. nov. and the most similar recent genera

1. Antenna with 11 antennomeres ( Fig. 1D )—Flagellomeres starting from fifth moniliform ( Fig. 1D ). Radial (r, 3-SR, SR1) vein and metacarp (1-R1) almost reaching distal margin of fore wing ( Figs 1G ; 2A ). Ovipositor sheaths ( Figs 1F ; 2B ) subtriangular, tapered towards apex and curved downwards, entirely covered by dense and short setae; sheath 2.6 × longer than its maximum basal width.......................................................................... Protoctonus gen. nov.

- Antenna with 12 – 16 antennomeres....................................................................... 2

2. Petiole of metasoma short and wide, its length almost equal to width at spiracle level. Propodeum without areola and keels. —Antenna with 14–15 antennomeres, moniliform. Ovipositor sheath straight, subtriangular shape, strongly tapered towards apex......................................................................................................................................................................................... Aclitus Foerster

- Petiole of metasoma elongate, its length distinctly larger than width at level of spiracles. Propodeum with delineated medial areola.............................................................................................. 3

3. Ovipositor sheaths curved downwards, gradually tapered towards acuminate apex. Petiole of mesosoma almost parallel-sided behind prominent spiracular tubercles. Antenna with 12–14 antennomeres, evenly thick.......... .. Calaphidius Mackauer

- Ovipositor sheaths straight or very weakly curved downwards, gradually tapered towards obtuse apex. Petiole of mesosoma distinctly concave behind prominent spiracular tubercles. Antenna with 13–16 antennomeres, slender but weakly thickened apically......................................................................... .... Falciconus Mackauer

Figures

FIGURES 1. Photos of Protoctonus groehni gen. et sp. nov. (female, holotype). A. Habitus, left side. B. Habitus, right side. C. Head and basal antennomeres, front view. D. Antenna. E. Head and mesoscutum, dorsolateral view. F. Metasoma and ovipositor, dorsolateral view. G. Wings. H. Distal part of fore wing.

FIGURES 2. Figures of Protoctonus groehni gen. et sp. nov. (female, holotype). A. Fore wing. B. Ovipositor sheaths.