Aegosoma vladzubovi Koshkin, Ivanov & Drumont, 2023

Koshkin, Evgeny S., Ivanov, Sergei N. & Drumont, Alain, 2023, Aegosoma vladzubovi sp. n., a new remarkable species from Central Vietnam (Coleoptera: Cerambycidae, Prioninae), Zootaxa 5319 (3), pp. 435-442 : 435-440

Aegosoma vladzubovi Koshkin, Ivanov & Drumont sp. n.

( Figs 1 , 3 A, B, C, D )

http://zoobank.org/ urn:lsid:zoobank.org:act:2EC2F6DF-7256-48F7-97DC-9B97F05652A6

Type material. Holotype ( Figs 1 A–D ): ♁, Vietnam, Quang Nam province, Tay Giang district, Axan [Mt.], 1300 m, VII.2019, leg. local collector (ex SIC, will be deposited in ZISP).

Paratypes ( Figs 1 E–H , 3 A–D ): 1 ♁, same data as holotype but IX.2019 (ex SIC, in EKC); 1 ♁, same data as holotype but V.2020 ( SIC); 1 ♀, Vietnam, Quang Nam province, Tay Giang district, Axan Mt. , 13.IV.2018, leg. local collector (ex VZC, will be deposited in ZISP); 1 ♁, same data but IV.2020 ( VZC) .

Description. Body length (measured from the tip of the mandible to the elytral apex): males: 44–58 mm (holotype: 45 mm), female: 62 mm. Body width: males: 12–16.3 mm (holotype: 12.5 mm), female: 20 mm. Habitus elongated, moderately depressed, rufous-orange and dark brown.

Male ( Figs 1 A–D , 3 A–D ). Head black, longer than wide, subcylindrical, densely covered with finely granules, between the eyes and directly behind them—in large, sparse granules. Gula densely and finely granulated over the entire surface, with large single granules, with erect pubescence from sparse rufous hairs. Mandibles large, black, shiny, strongly punctated in the external side except for apex; inner side of left mandible with a large tooth; right mandible with a small one. Jugular process shiny, approximately equal to lower eye lobe or slightly wider, the lower portion covered with large granules. Labrum with rufous setae. Clypeus densely granulated. Antennal tubercles small, their top part is shaped as a semicircular visor. The eyes are relatively small, kidney-shaped; the upper lobe is much less than the lower one. Median groove between eyes long, narrow and quite deep. Frons between antennal tubercles and vertex densely covered with rufous-orange lying pubescence. This pubescence behind the eyes gradually expands and weakens.

Antennae 11-segmented, unicolor black with bright shine almost the entire length, 1.13–1.22 times as long as body, segment III with internal smooth flat-concave area at the base. Scape is thick and subcylindrical, densely granulated. Segments III, IV and V thick, very long, roughly sculptured, with strong denticules at the inner side gradually decreasing towards the top of antenna. Segment III is the longest, segment IV is 1.1–1.3 times shorter than it. Segment V is 1.2–1.4 times shorter than segment IV. Segments VI – XI appear matte due to very fine punctation. Due to very fine punctation the apical tip of segment V looks matte over the entire surface; the apical tips of segments III and IV look matte only on the outside and below. Segment V almost reaching to the elytral apex. Segment IV is shorter than segment III. Segment V is approximately 1.5–1.7 times shorter than segment III. Segments VI–XI short. Segment VI is longer than segment VII, segments VIII–X are equal. Last segment is flattened and pointed at the apex.

Pronotum black or dark brown, transverse, trapezoidal shaped; ratio between maximum width and length is 1.55– 1.65. Anterior margin straight. Posterior margin convex at middle and forms two protruding angles. Lateral margins with two rounded coarse-grained prominences after noticeable anterior narrowing. The rest of disc is densely and finely granulated. The area at the angles of pronotum covered with very dense orange lying hairs forming four transverse spots. In some specimens the spots on each side of pronotum merge into one along the lateral margin. Central area of disc is sparsely covered with lying short light hairs.

Scutellum black, shiny, medium-sized, tongue-shaped, with a rough surface, covered with sparse short light hairs.

Elytra flattened, subparallel, long, 2.4–2.7 times longer than its width in humeral area, widest at 1/4 from the base, with well-defined sutural teeth at apices. Elytra rough, dark brown or dark gray with purple tint along second inner costa and along the sutural margin, covered with scattered granules reaching a high density in the area between first inner costae and the sutural margin and also on humeri. The rest of the elytra is densely covered with pubescence from short rufous-orange lying hairs. A large area with intense rufous-orange pubescence located at the base of elytra between scutellum and humeri, from there it continues as a less intense rufous narrow stripe along the first inner costa. A wide band from intense rufous pubescence runs along the elytron outer margin. The outer and sutural margins of the elytra are bordered with a rather wide dark line. The elytra look striped due to the alternation of rufous-orange and dark areas and bands. In one male, rufous-orange pubescence of varying intensity covers most of the elytral surface ( Fig. 3 C ). Elytron with four subparallel costae. Two inner costae are barely raised and underlined by a coarse alignment of granules, start from humeri, subparallel to each other in basal part and connected in 1/4 from apex elytra. Two outer costae shorter and almost inconspicuous. Elytral epipleuron narrow, gradually tapering towards apex, with a relief from a combination of transverse grooves along the outer margin and small granules along the inner margin.

Legs black, flattened, slender. Femur with very sparse and very short pubescence, tibia (except protibia) with sparse and short golden hairs. Pubescence of protibia dense along the lower margin and adjacent part of the inner side, becoming denser towards the apex. Pro- and mesofemur and pro- and mesotibia granulated (the fore ones—to a greater extent). Mesofemur smooth, sparsely and finely punctate at base, metafemur smooth, sparsely and finely punctured in basal half. Inner side of metafemour smooth and shiny, outer side with sparse and fine punctures. Metatibia granulated in the form of scales. Claws segment slightly longer or equal the combined three others segments.

Prosternum black, with sparse pubescence from short whitish setae. Prosternal process is long, gradually expanding towards the apex. Mesepisternum, outer margin of mesepimeron, metasternum and metapimeron densely covered with semi-lying orange-rufous hairs. Coxae with sparse and lighter pubescence. Abdominal sternites black-brown, glabrous, finely punctated and slightly covered with sparse short light setae. Last sternite with wide emargination, covered with rufous hairs at the apex.

Female ( Figs 1 E–H ). The female has the same morphological features as the male, differing in some details. Antenna shorter than body and reaching the last quarter of elytra; ratio between antenna and body lengths ca. 0.8. The granulation and denticulation of the antenna is less pronounced. Pronotum shorter than in males, more trapezoidal, ratio between maximum width and length is 2.1. The rufous-orange pubescence in the middle part of the elytra is less pronounced. A significant part of the elytra is glabrous and strongly granulated.

Diagnosis. Aegosoma vladzubovi sp. n. is characterized by long unicolor black antennae with strongly developed segments III, IV and V, while segment V slightly does not reach the apices of the elytra, and intense but irregular bright rufous-orange pubescence of the elytra, pronotum and head.

The new species is most similar to A. kusamai ( Komiya, 1999) ( Fig. 2 ) differing from it in the following features:

- irregular rufous-orange pubescence of elytra, more pronounced along the outer margin, at the base (except for sutural and humeral areas) and along first inner costa; the remaining areas of the elytra are dark, as they are almost without pubescence. Therefore, the elytral surface looks like it consists of alternating rufous-orange and dark longitudinal stripes (in A. kusamai , dense pubescence is yellow wax color and it evenly covers the elytral surface, dark glabrous areas are missing except in humeri);

- inner elytral costae are well defined (in A. kusamai only separate granules are visible due to dense pubescence);

- elytra slightly narrowed towards apex in males (in A. kusamai elytra distinctly tapered towards apex);

- pronotum slightly narrows at anterior margin, lateral margins are rounded after anterior narrowing; anterior margin without emargination; spots on pronotum are rufous-orange (in A. kusamai , pronotum is noticeably narrowed at anterior margin which has a small emargination; lateral margins almost straight after anterior narrowing; spots on pronotum are yellow wax color);

- shorter antennae in males with length about 1.13–1.22 times as long as body (in A. kusamai antennae longer, about 1.35–1.43 times as long as body);

- in males, antennal segment V straight or almost straight and does not extend beyond elytral apex (in A. kusamai , it is noticeably curved and extends beyond elytral apex);

- in males, antennal segments VI–XI are shorter and wider than those of A. kusamai ;

- in female, denticulation on the inner side of antennal segments III–V is more expressed (females of A. kusamai have fewer denticules and they are smaller);

- pubescence of mesepisternum, outer margin of mesepimeron, metasternum and metepimeron is denser and orange-rufous (in A. kusamai pubescence is sparser and lighter);

Also, Aegosoma vladzubovi sp. n. has some similarities with A. george , A. mientrung and A. dorei with which it occurs sympatrically.

A new species is similar to some specimens of A. george in length and antenna structure ( Figs 3 G, H ). At the same time A. vladzubovi sp. n. distinctly differs from A. george in the following main features:

- unicolor black antennae and legs (in males of A. george antennal segments I–V and legs are red);

- antennal segments IV and V are longer than those of A. george ;

- dense rufous-orange pubescence on elytra and pronotum which forms a characteristic pattern (in A. george elytra glabrous, less granulated, without any pubescence; pronotum is uniformly pubescent with very short pale hairs);

- less visible costae with separate granules (in A. george costae are strongly expressed as continuous lines).

A. vladzubovi sp. n. differs from A. mientrung and A. dorei in longer antennae, their different structure, intense and uneven rufous-orange pubescence on the elytra and pronotum (in A. mientrung and A. dorei elytra and pronotum are almost evenly covered with a barely visible pale pubescence) ( Figs 3 E, F ).

Distribution. Central Vietnam (currently only known from Axan Mount in A Xan commune, Quang Nam province).

Etymology. The new species is dedicated to amateur coleopterist Vladimir Yu. Zubov (Lesozavodsk, Primorsky Kray, Russia), who provided the first two specimens of this rare species for our study.

Discussion. Aegosoma vladzubovi sp. n. should be included into Aegosoma kusamai species-group which until recently consisted of a single species— A. kusamai ( Komiya, 1999) ( Do 2015) . Males of these species are characterized by very long antennae with long segments III, IV and V. At the same time, the new species has significant differences from A. kusamai in the coloration and pubescence of the elytra, morphology of the pronotum, antennae, and some other features. A. kusamai inhabits Southern Myanmar (Kayin State and Tanintharyi Region) and Northwestern Thailand (Chiang Mai and Mae Hong Son Provinces). The new species was found only in a limited area in Central Vietnam and inhabits mountain forests at altitude about 1300 m. The ranges of A. vladzubovi sp. n. and A. kusamai do not overlap. The gap in the distribution of these species is at least 1000 km in a straight line ( Fig. 4 ). In the vicinity of Axan Mount, A. vladzubovi sp. n. co-occurs with four other Aegosoma species: A. dorei , A. mientrung , A. george ( Phan et al. 2022; Ripaille et al. 2022) and A. doi . The latter species is reported for the first time for this area: 1 ♁, 2 ♀, C. Vietnam, Quang Nam province, Tay Giang district, Mt. Axan, 1300 m, III.2018 (SIC).

Figures

FIGURE 1. Aegosoma vladzubovi sp. n., habitus. A, B, C, D—holotype ♁, 45 mm, Vietnam, Quang Nam province, Tay Giang district, Axan [Mt.], 1300 m, VII.2019 (in ZISP); E, F, G, H—paratype, ♀, 62 mm, Vietnam, Quang Nam province, Tay Giang district, Axan Mt., 13.IV.2018 (in ZISP). A, E—dorsal view, B, F—ventral view, C, G—lateral view, D, H—frontal-dorsal view. (Photos by Evgeny Koshkin).

FIGURE 2. Aegosoma kusamai (Komiya 1999), habitus. A, B, C, D—♁, 52 mm, Thailand, Chiang Mai, Fang, VII.2014 (in ADC); E, F, G, H—♀, 45 mm, Thailand, Chiang Mai, Om Koi, VI.2014 (in ADC). A, E—dorsal view, B, F—ventral view, C, G—lateral view, D, H—frontal-dorsal view. (Photos by Noël Mal).

FIGURE 3. Aegosoma spp., habitus. A—A. vladzubovi sp. n., paratype ♁, 58 mm, Vietnam, Quang Nam province, Tay Giang district, Axan Mt., IV.2020 (in VZC); B—A. vladzubovi sp. n., paratype ♁, 44 mm, Vietnam, Quang Nam province, Tay Giang district, Axan [Mt.], 1300 m, IX.2019 (in EKC); C, D—A. vladzubovi sp. n., paratype ♁, 53 mm, same data as figure B but V.2020 (in SIC); E—A. dorei Drumont, Gouverneur, Tavakilian & Collard, 2018, ♁, 51 mm, Vietnam, Yen Bai province, Mu Cang Chai, 1700 m, V.2016 (in SIC); F—A. mientrung Ripaille, Phan & Drumont, 2022, ♁, 60 mm, Vietnam, Quang Nam province, Tay Giang district, Axan Mt., 1300 m, V.2018 (in SIC); G—A. george Do, 2015, ♁, 63 mm, Vietnam, Lam Dong province, Lac Duong district, Bidoup Nui Ba National Park, 25.IV.2016 (in EKC); H—A. george, ♀, 50.5 mm, Vietnam, Da Nang province, Ba Na Mt., 1450 m, V.2015 (in EKC).A–C, E–H—dorsal view, D—ventral view. (Photos A, B, G, H by Evgeny Koshkin, photos C, D, E, F by Sergei Ivanov).

FIGURE 4. Distribution records of Aegosoma vladzubovi sp. n. (red circle) and A. kusamai (blue circles; blue quadrate is presumable type locality—«Tenasserim»).