Aphidius brethes Tomanović & Kocić, 2025

Aphidius brethes Tomanović & Kocić View in CoL sp. nov.

Figs 2 View Figure 2 , 3 A – H View Figure 3 , 4 A – H View Figure 4

Type material.

Holotype: • 1 ♀, Argentina, sample 85 APHI , 34°27'35"S, 61°48'46"W (Leandro N. Alem County), 29. XI. 2022, collected by Malaise traps in field margin of first-crop soybean, leg. M. Devoto & collabs. Holotype deposited in coll. Museo Argentino de Ciencias Naturales ” Bernardino Rivadavia ”, Argentina ( MACN - En) GoogleMaps .

Paratypes: • 1 ♀, sample 540 APHI , Argentina, 33°56'16"S, 59°37'04"W (Baradero County), 28. IV. 2023, collected by Malaise traps in field margin of first-crop soybean, leg. M. Devoto & collabs. ( MACN - En) GoogleMaps ; • 1 ♀, sample 609 APHI , Argentina, 34°29'22"S, 61°44'47"W (Exaltación de la Cruz County), 04. VIII. 2023, collected by Malaise traps in margin of wheat field, leg. M. Devoto & collabs. ( MACN - En) GoogleMaps ; • 1 ♀, sample 519 APHI , 34°28'56"S, 61°47'18"W (Leandro N. Alem County), Argentina, 04. V. 2023, collected by Malaise traps in margin of second-crop soybean field, leg. M. Devoto & collabs. ( FBUB) GoogleMaps ; • 1 ♀, sample 580 APHI , 33°56'16"S, 59°37'04"W (Baradero County), Argentina, 04. V. 2023, collected by Malaise traps in wheat field, leg. M. Devoto & collabs. ( NMB) GoogleMaps ; • 1 ♂, 549 APHI , 33°55'16"S, 59°37'42"W (Baradero County), Argentina, 04. VIII. 2023, collected by Malaise traps in wheat field, leg. M. Devoto & collabs. ( MACN - En) GoogleMaps .

Diagnosis.

By wing venation pattern (M + m-cu vein partly developed under r-m vein) (Fig. 3 H View Figure 3 ) Aphidius brethes sp. nov. belongs to subgenus Lysaphidus . Aphidius brethes sp. nov. belongs to Aphidius species group with costulate anterolateral area of petiole like all known Aphidius species in South America (e. g. A. matricariae Hal. , A. rhopalosiphi Luzhetzki , A. uzbekistanicus De Stefani-Perez ), except for A. ervi Hal. that possesses rugose and A. avenae Hal. , A. platensis Brèthes and A. colemani Viereck that have costate anterolateral area of petiole. New species differs from the mostly known Lysaphidus species by having 16–17 - segmented antennae (Fig. 3 B View Figure 3 ), four maxillar palpomeres and two labial palpomeres, while other species have 12–14 segmented antennae and usually three maxillar and two or one labial palpomeres (e. g. Aphidius arvensis (Starý) , A. erysimi (Starý) , A. adelocarinus Smith , A. rosaphidis Smith ). Aphidius brethes sp. nov. by 16–17 - segmented antennae and four maxillar and two labial palpomeres morphologically resembles A. viaticus (Sedlag) (15, 16 - segmented antennae) and A. ramithyrus Smith (15, 16 - segmented antennae). Moreover, it differs from A. viaticus on having the proportion between length and width of petiole at spiracles level 2.3–2.4 × (Fig. 3 F View Figure 3 ), while A. viaticus possesses 3.0–3.5 petiole proportion. The new species differs from A. ramithyrus by shorter flagellomere 1 (proportion between length and width of F 1 is 2.6–2.8 × (Fig. 3 C View Figure 3 ), while in A. ramithyrus it is 3.0–3.2 ×) and longer petiole (2.3–2.4 × as long as width at spiracles level (Fig. 3 F View Figure 3 ), while in A. ramithyrus 2.0–2.2). Furthermore, Aphidius brethes sp. nov. is mostly yellow colored (Fig. 2 View Figure 2 ), while A. ramithyrus and A. viaticus are darker. Aphidius viaticus parasitizes Pleotrichophorus glandulosus (Kalt.) aphid associated with Artemisia plants, while Aphidius ramithyrus parasitize Capitophorus spp. aphids. We assume that A. brethes sp. nov. parasitizes cereal or soybean aphids.

Description.

Female (holotype). Length. Body 1.5–1.7 mm; fore wing 1.6 mm; hind wing 1.2 mm.

Head (Fig. 3 A View Figure 3 ). Transverse, wider than mesosoma at tegulae. Eyes medium sized, oval, laterally prominent. Face moderately setose. Tentorial index (tentoriocular line / intertentorial line) 0.60–0.65. Clypeus with 8–12 long setae. Labrum distinct, with 7–8 short setae on outer margin. Malar space equal to 0.33–0.38 of longitudinal eye diameter. Mandible bidentate, with 9–10 setae on outer surface. Maxillar palpi with 4 palpomeres, labial palpi with 2 palpomeres. Antenna 16, 17 - segmented, moderately thickened (Fig. 3 B View Figure 3 ). Pedicel subsphaerical (Fig. 3 C View Figure 3 ). First flagellomere (F 1) subequal or slightly shorter than second flagellomere (F 2) and 2.6–2.8 × as long as its maximum width (Fig. 3 C View Figure 3 ). F 1 and F 2 bearing 0–1 and 2–3 longitudinal placodes, respectively (Fig. 3 C View Figure 3 ). Flagellomeres covered uniformly with semi-erect setae subequal to half of segments diameter.

Mesosoma. Mesoscutum (Fig. 3 D View Figure 3 ) smooth, covering pronotum from above. Notaulices not present. Mesoscutum sparsely setose with one row of setae laterally (Fig. 3 D View Figure 3 ). Scutellum oval, bearing 6–7 long setae. Propodeum areolated with wide central areola, but sometimes missing upper carina (Fig. 3 E View Figure 3 ). Upper and lower areolae of propodeum with 1–2 and 1–3 long setae on each side. Fore wing (Fig. 3 H View Figure 3 ) densely pubescent, marginal setae longer than those on surface; pterostigma, 2.9–3.1 × as long as its width, 1.9–2.4 × as long as R 1 vein (= metacarpus).

Metasoma. Petiole (Fig. 3 F View Figure 3 ) elongate, dorsally striated at the middle, slightly convex dorsally; its length 2.3–2.4 × its width at spiracles, 1.8–2.0 × its width at the base (Fig. 3 F View Figure 3 ); 10–12 setae positioned on dorsal posterior part; one long seta posterior to spiracles. Anterolateral area of the petiole with 10–12 costulae. Ovipositor sheath (Fig. 3 G View Figure 3 ) moderately elongated, wide at base, dorsally slightly convex, narrowed toward tip, apically truncated, bearing two long setae at dorsal margin. Length of ovipositor sheath 1.6–2.0 × its maximum width at base, 2.7–3.0 × its minimum width at tip.

Coloration. General body color yellow to light brown (Fig. 2 View Figure 2 ). Scapus and pedicel yellow to light brown, annellus yellow, yellow ring at the base of F 1, remaining part of antennae brown. Head light brown, eyes dark. Mouthparts except tips of mandible yellow. Pronotum, mesoscutum and mesopleuron light brown. Propodeum yellow. Legs with yellow coxae and trochanters, remaining parts of legs light brown. Wings hyaline, venation yellowish brown. Petiole yellow, other metasomal terga yellow to light brown, dorsally darker. Ovipositor sheath dark brown.

Male (Figs 4 A – H View Figure 4 ). Antenna 17 - segmented (Fig. 4 B View Figure 4 ). Maxillar palpi with 4 palpomeres, labial palpi with 2 palpomeres. Flagellomeres 1 and 2 shorter than in female, and both 1.9 × as long as wide, each bearing 7–8 longitudinal placodes (Fig. 4 C View Figure 4 ). Tentorial index approx. 0.43, malar index approx. 0.63. Fore wing venation as in female (Fig. 4 H View Figure 4 ). Fore wing marginal setae distinctly longer than those on surface; pterostigma widely triangular, 2.8 × as long as its width and 1.9 × as long as R 1 vein (= metacarpus) (Fig. 4 H View Figure 4 ). Petiole (Fig. 3 F View Figure 3 ) 2.9 × its width at spiracles. Aedeagus oval (Fig. 4 G View Figure 4 ) with 10–15 setae laterally. Body slightly darker than in female, head and thorax light brown, antenna brown, mouthparts yellow. Wings slightly transluscent. Legs brown with light yellow patches at ventral and tip of segments. Petiole and propodeum yellow. Coxae and trochanters yellow, remaining parts of legs light brown to brown. Metasoma light brown to brown. Body length: 1.5 mm.

Distribution.

Aphidius brethes sp. nov. was collected in Argentina and currently it is its only known distribution.

Aphid host.

Unknown, collected by Malaise traps within field crops.

Etymology.

The new species takes its name by Juan Brèthes, an Argentine scientist, naturalist, entomologist who has described several aphid parasitoid species.