Aegosoma xentoc, Do, Cuong & Drumont, Alain, 2014

Do, Cuong & Drumont, Alain, 2014, Description of a new species of Aegosoma Audinet-Serville, 1832 from Vietnam (Coleoptera: Cerambycidae: Prioninae), Zootaxa 3793 (2), pp. 291-296 : 291-296

Aegosoma xentoc new species

( Figs 1–11 )

Material examined. Holotype: ♂ Bidoup National Park, Lam Dong Province, Vietnam, March 2013, deposited in the Vietnam National Museum of Nature, Hanoi, Vietnam. Paratypes: 1♂ 1♀ same data as holotype deposited in Cuong Do Collection 19♂♂, 5♀♀, same data as holotype deposited in Xung Le Collection; 1 ♂ Khanh Khoa border, Lam Dong Province, Vietnam, 1625m, 19.IV.2010, leg. A. Prokofiev, housed in Alain Drumont Collection.

Etymology. The species name is the name for longhorn beetles in Vietnamese.

Description. Male (based on Holotype). Body moderately large, elongated, red brown in color and covered with short yellow hairs ( Figs 1–2 ).

Head longer than wide, cylindrical, uniformly covered with small granules, somewhat expanded laterally at the midpoint from eye to base; labrum with an apical tuft of yellow setae; mandible red brown with inner edge very sharp and shiny black; curved inward at distal 1/3; right mandible with a lateral carina at basal 1/3 made by a concave area. Underside of head round and granulated.

Front strongly concave at middle, apical edge divided into three lobes, surface of middle concave part somewhat less granular than two lateral parts. Eyes with upper lobe smaller than lower lobe.

Antennae long with 11 segments, length of segments I–VIII about equal to body length (not including mandible), densely granulated on segments I to IV and smoother on segments V to XI. Scape large and robust, length about 2 times its width. Segment III long, about 1/3 length of entire antenna and equal to combined length of segments IV–VII; inner side with a distinct groove; somewhat curved at distal 1/3. Segment IV straight and more slender than segment III and about 1.3 times the length of segment V; and inner groove visible. Segments V–XI smoother and clearly different: segment V about 1.25 times segment VI, segment VI as long as segment XI and about 1.3 times segment VII, segments VII, VIII, IX and X about equal in length. Segments V–IX nearly straight but segment X curved inward at middle. Segment XI flattened and somewhat curved inward. The inner groove not found in segments V–XI.

Pronotum about half as long as wide at base, widest at base and narrowest at apex. Lateral sides rounded, posterior edge forms three lobes, width of the middle as much as 2 times that of each lateral lobe. Dorsal surface of pronotum convex at two points, forming two dorsal lobes.

Scutellum with apical edge as long as its length and with round posterior edge.

Elytra flattened, elongate, about 5 times as long as wide; apex rounded with a small spine. Elytron with two very distinct and raised costae that run along the elytron and fuse at distal quarter to form a single costa.

Legs flattened, slender, femur nearly as long as tibia. Tarsi of the three pairs of legs are similar in shape, with segment 1 longest; segment 2 shortest, as long as about half of width; segment 3 as long as wide; claw segment as long as segments 1+2+3.

Aedaegus. ( Figs 5–8 ) Penis with curved, obtuse apex and two long flattened branches. Tegmen with a deep cleft at middle, forming two branches ending with apical tufts of hairs. Length of tegmen about 4.5 times that of each branch. Lateral side of branches parallel for distal half and expanded basely.

Female ( Figs 3–4 ): Similar to male but larger in size but antennae shorter than body and more slender. The ovipositor ( Figs 9–11 ) with two apical coxite lobes slightly separated laterally. The coxite lobes narrow at base and expand apically, dorsal side with tufts of hair at apical quarter. Each coxite lobe bears a cup-shaped stylus; in ventral view, a row of hairs runs around inner side of stylus.

Variation observed in the paratypes: There is no obvious variation among paratypes except the size variation.

Measurements:

Male holotype length (without mandible): 51 mm

Male holotype wide (measure at widest point): 14 mm

Variation in size of males: length 35.5–54.5 mm, wide 12–18 mm

Variation in size of females: length 44.5–54 mm, wide 15–17 mm

Habitat: The new species was found in low disturbed forests with elevation from 1200m to 1600m, most of the time the area is cloudy, cold and wet. High humidity condition often gained from the sea nearly all months of the year ( Fig. 12 ).

Diagnosis. Based on the male antenna, members of Aegosoma can be divided into 4 main groups, as follows:

• Group 1 contains a single species, A. kusamai . Male of this species differs significantly from all other species in length of antenna, which is very long, exceeding apical end of elytra by segment V. Segment IV of antenna extremely developed and longer than segments VI–XI combined.

• Group 2 includes two members: A. cuneicornis and A. kasurai , with antenna of male remarkably short, shorter than the length of the body. Segment IV of the antenna short, nearly equal to segment V.

• Group 3 includes six species: A. guerryi , A. sinicum , A. ornaticolle , A. hainanensis , A. ivanovi , and A. scabricorne . As for Group 1, the male antenna is longer than the body. Segment IV of antenna shorter than that of A. kusamai in Group 1 but longer than that of two species in Group 2. This group is similar to group 4, with segment IV of antenna about the length of segments V and VI combined.

• Group 4 includes A. annulicornis , A. giganteum , A. musaamani , A. ossea , and A. pallida . They are similar to members in Group 3 in general structure, but their bodies and antennae are light in color. Males of Group 4 have slender antennae; segments III and IV of antenna not thick and robust as in members of Group 3.

The new species, A. xentoc , differs from all species in the four groups above and requires the creation of a new group. Unlike the members of Group 2, the male antennae are longer than body. Unlike A. kusamai of Group 1, only by segments VII–VIII does the antenna extend beyond the elytra in A. xentoc . The length of antennal segment IV of male A. xentoc also is shorter than that of A. kusamai , shorter than combined length of segments V and VI.

Figures

FIGURES 12. Photo of habitat of Aegosoma xentoc, a cold and cloudy day on Hon Giao summit (Bidoup National Park), photo by Ngo Van Huyen (a ranger of Bidoup National Park)

FIGURES 1 – 4. Aegosoma xentoc: 1. ♂, dorsal view; 2. ♂, ventral view; 3. ♀, dorsal view; 4. ♀, ventral view.

FIGURES 5 – 8. Male genitalia of Aegosoma xentoc: 5. penis, ventral view; 6. penis, lateral view; 7 tegmen, ventral view; 8 tegmen and apical part of penis.

FIGURES 9 – 11. Ovipositor: 9. ventral view; 10 coxite lobe and stylus, ventral view; 11 coxite lobe and stylus, dorsal view