Aristobia reticulator (Fabricius, 1781)

Agarwala, B. K. & Bhattacharjee, P. P., 2015, Redescription of Aristobia reticulator (F., 1781) (Coleoptera: Cerambycidae: Lamiinae), with a Taxonomic Note and Record of a New Food Plant for Adults in Northeastern India, The Coleopterists Bulletin 69 (2), pp. 205-212 : 206-210

Aristobia reticulator (F., 1781)

( Figs. 2–8 )

Lamia reticulator F., 1781 (type location: unknown in “ India Orientalis ”, lectotype, female): Zimsen 1964 .

Cerambyx testudo Voet, 1778 (synonym) (nomen nudum; type location: unknown in “ British India ”).

Celosterna clathrator Thomson, 1865 (synonym) (type location: Sylhet in Bangladesh). Aristobia clathrator: Thomson 1868 .

Aristobia reticulator (F., 1781): Lacordaire 1869.

Aristobia testudo ( Voet, 1778) : Aurivillius 1922; Beeson 1941; Breuning 1943; Hua 2002; Mukhopadhyay and Halder 2004; Weigel 2006.

Aristobia reticulatrix (F., 1781): Löbl and Smetana 2010.

Material Examined. 1♀, 07.x.2006, coll. O. Hemchandra, host plant – Cajanus cajan (L.) ( Fabaceae ), Barapani (25°42′18.7″ N and 91°58′11.8″ E, 910 m), Meghalaya, India; 1♂ and 2 ♀, 18.viii.2013, colls. P. P. Bhattacharjee and D. K. Sinha, host plant - Microcos paniculata L. ( Malvaceae ), Kaimaicherra (23°49′14.8″ N and 91°26′30.6″ E, 80 m), Dhalai district, north Tripura, India; 3 ♂ and 1♀, 20.xi.2013, coll. J. M. Barman and D. K. Sinha, 3 ♂, 12.xii.2013, colls. P. P. Bhattacharjee and D.K. Sinha, host plant – M. paniculata, Ichanchandranagar (23°45′20.79″ N and 91°15′30.31″ E, 16 m), west Tripura, India ( Fig. 1 ).

Diagnosis. The species is treated under the genus Aristobia Thomson, 1868 chiefly for having the antennal insertions strongly elevated and divergent, antennae with the third segment and often some of following segments with tufts of hairs or bristles at their apices, and the third segment longer than the fourth segment ( Aurivillius 1922; Beeson 1941; Breuning 1943; Gressitt 1951). The nearest taxonomic relative of the species is A. approximator ( Thomson, 1865) , which is characterized by the presence of a strong tuft of hairs at the apical half of the third antennal segment only in both sexes, whereas A. reticulator possesses tufts of hairs on the apices of the third, fourth, and most often on fifth segments; these tufts are most prominent on the third segment, less so on the fourth segment, and feebly so, if present, on the fifth segment ( Hua 2002; Jiroux et al. 2014).

Distribution. India (Assam, Manipur, Meghalaya, Sikkim, Tripura), Bangladesh, China, Laos, Myanmar, Nepal, Thailand, Vietnam ( Fig. 1 ).

Redescription of Male. n = 7. Body subcylindrical, 20.97–26.34 mm long, 7.57–9.52 mm maximum width in subapical region of elytra ( Table 1); dorsal surface clothed with thick orange or yellow pubescence with black reticulations ( Fig. 2a ). Head: Front of head ( Fig. 3 ) gently sloping from base to apex, highly sclerotized, black, with prominent median suture that runs through frons and clypeus, both glossy black and clothed with thin pubescence; labrum shield-like, broadly hinged to clypeus by yellow, gelatin-like clypeolabral membrane; mandibles strong with broad bases attached to clypeus, incisor smooth, curved and pointed, maxillary and labial palps 3-segmented, black, with apical segment longest, bearing sparse, white setae and round tips; gena similar to clypeus and frons in texture and color; vertex ( Fig. 4 ) with distinct median suture and elevated, deeply notched, divergent antennal sockets, with inverted trident-shape and orange pubescence with black bands in between, compound eyes elliptical below antennal sockets but broader and longer facing frons; antennae 11-segmented ( Fig. 5 ), without tubercles, 27.31–31.88 mm long and, on average, 1.24 times longer than the body, orange in color except scape, 2 nd segment and apices of 3 rd, 4 th, and 5 th segments dark, 3 rd segment covered with yellow bristles except on apical 2/5 which is covered with large tufts of deep brown bristles, 4 th and 5 th segments similar to 3 rd segment except tufts of deep brown bristles in the apical regions smaller and feebly so on inner side of 5 th segments (in some preserved specimens, these segments bear scars which represent accidental erosion of yellow bristles during handling in study); scape 3.50–4.32 mm long; 2 nd segment

208 THE COLEOPTERISTS BULLETIN 69(2), 2015

shortest, 0.74–0.98 mm long; 3 rd segment longest, 4.52–5.52 mm long; 4 th segment 3.89–4.46 mm long, shorter than 3 rd segment, 5 th (2.92–3.51 mm long) to 10 th (1.45–1.77 mm long) gradually shorter, apical segment (2.09–2.72 mm long) longer than previous ones ( Table 1). Thorax: Pronotum ( Fig. 4 ) wider than long, 3.96–5.62 mm long, 6.51–8.23 mm wide in the middle, thinly pubescent throughout, with 2 well-defined, longitudinal, black vittae converging anteriorly to vertex and posteriorly around scutellum, vittae widest medially, extending laterally into extensive area of orange pubescence terminating at pronotal tubercles with blunt apices; pronotal disc somewhat convex in middle but slightly depressed above and below, with a few sparse and shallow punctures, devoid of a spine, without a carina, maximum width narrower than maximum width of elytra; scutellum triangular with rounded apex, orangeyellow; pro- and metacoxal cavities open, midcoxal cavity covered with conspicuous black protuberance with its circular base covered with whitish hairs and a distal rounded apex ( Fig. 6 ), proepisternum broad, somewhat tongue-shaped, proepimeron thinner than proepisternum, compressed between coxae above and collar region below, encircling procoxa on each side; mesepisternum and mesepimeron broader than long, placed laterad of mesosternum; metepisternum and metepimeron elongated, placed side by side laterad of metasternum. Legs: Black, pubescent ( Figs. 2a , 4a ); midtibial groove absent, hind legs longer than mid- and forelegs; tarsi 4-segmented, dorsal surface black, convex and pubescent, ventral surface faint yellowish grey, flat and incrassate, 3 rd segment deeply bilobed, last segment elongated, with deep furrow on ventral side and pair of terminal, pointed, curved, and divaricate claws ( Fig. 7a–c ). Elytra: Emarginate apically, convex, 15.29–18.86 mm long, clothed with a reticulation of orange or yellow and black pubescence, usually distinguishable as 7 (n = 5), seldom 6 (n = 1) or eight (n = 1) orange spots of irregular shapes and various sizes on the inner margins and an equal number on the outer margins present linearly in anterior-posterior direction on each elytron, one or sometimes 2 additional smaller spots present medially between inner and outer spots in the apical half, some of the spots variously but not completely fused, not all spots symmetrical in their disposition on elytra ( Fig. 2a ). Abdomen: Completely covered dorsally by elytra, ventral surface shiny black, sparsely setose, with 5 distinct sternites ( Fig. 8 ), 1 st sternite longer than next 4 sternites, median region strongly projected between hind coxae; membranous joint between 1 st and 2 nd sternites very thin and flat, those between 2 nd and 3 rd, 3 rd and 4 th, and 4 th and 5 th sternites with curved lines, characteristic of the male, which become progressively prominent posteriorly ( Fig. 8 ).

Redescription of Female. n = 4. Body color and shape generally similar to that of male; 30.22–33.76 mm long, 11.00– 12.60 mm maximum width in the subapical region of elytra ( Table 2) ( Fig. 2b ). Head: Frons ( Fig. 3 ) black, hairy, with distinct median suture; antenna 11-segmented, 34.05–37.72 mm long and, on average, 1.12 times longer than body length, with tuft of black bristles on apices of 3 rd, 4 th, and 5 th segments, scape about 4.80–5.06 mm long, 2 nd segment shortest, 0.94– 1.45 mm long, 3 rd segment longest, 6.12–6.89 mm long, bearing prominent scars by lack of pubescence, other apical segments uniformly pubescent or hairy, 4 th segment 4.78–5.46 mm, shorter than 3 rd, 5 th (3.70–4.19 mm long) to 10 th (1.58–1.94 mm long) segments gradually shorter, apical segment (2.22–2.53 mm long) longer than previous ones ( Figs. 2b , 5 ). Thorax: Pronotum ( Fig. 4 ) larger than that of males, 5.32–6.17 mm long, 9.65–10.67 mm wide, with 2 longitudinal black vittae alternating with orange or yellow pubescence, vittae widest in middle, extending laterally into extensive areas with orange pubescence terminating in pronotal tubercles as in males, pronotal margins, midcoxal cavities, episterna, and epimera as in males; midtibial groove absent, hind legs longer than mid- and fore legs ( Table 2); tarsi 4-segmented, 3 rd segment deeply bilobed, last segment elongated, with a pair of divergent claws ( Fig. 7a–c ). Elytra: Length 22.49–24.96 mm, clothed with a reticulation of orange or yellow and black pubescence, distinguishable as 8 (n = 2) or seldom 7 or 9 (n = 1 each) orange or yellow semiround to roundish spots on inner margins and an equal number on the outer margins, these disposed linearly in anterior-posterior direction on each elytron, 1–2 additional linear rows of spots present medially between inner and outer spots on apical half of elytra, some spots variously or completely fused, not all spots symmetrical in their disposition ( Fig. 2b ). Abdomen: Ventral surface shiny black, thinly covered with black pubescence, with 5 sternites, membranous joint between 1 st and 2 nd sternites very thin, those between succeeding sternites with flat lines which become progressively prominent except the last joint with curved lines ( Fig. 8 ). In other characters, similar to males.

Adults were repeatedly found feeding on the bark of M. paniculata in western Tripura districts of northeastern India, including branches infested by termites that also feed on the bark. This is a new adult food plant record for this beetle in its distribution range from Asia-Pacific region.

Taxonomic Note. Described originally as Lamia reticulator by Fabricius in 1781 from ‘ India Orientalis’, this beetle was later described as Cerambyx testudo by Voet in 1778 from an unknown location in British India. Until recently, two species collected from locations in China, India, Laos, Myanmar, Nepal, and Vietnam were treated under the genus Aristobia , chiefly in having the antennal insertions strongly divergent and the antennae with the third segment, and often some of following segments, with tufts of hairs or bristles at their apices ( Aurivillius 1922; Beeson 1941; Breuning 1943; Gressitt 1951; Hua, 2002; Mukhopadhyay and Halder 2004). Jiroux et al. (2014), while reviewing the tribe Monochamini , examined the original specimens and illustrations of L. reticulator and C. testudo and another species, Celostoma clathrator , from Bangladesh and found that the three species share the essential morphological characters: body shape and size; reticulation and life color pattern of head, antennae, thorax, abdomen and legs; pronotum with two median, longitudinal, black pubescent bands; and antennae 11-segmented with tufts of hairs on the apices of the third and fourth segments and sometimes the fifth segment. Following the rules of the International Commission of Zoological Nomenclature (ICZN: article 11 read with 13), Jiroux et al. (2014) retained Lamia reticulator as the oldest valid name, treated C. testudo as a nomen nudum and C. clathrator as a synonym. They treated these under the name Aristobia reticulator with India as the type locality (unknown collection location) and considered the original material of Lamia reticulator as the lectotype deposited at the British Natural History Museum, London.

Figures

Fig. 2. Aristobia reticulator, habitus. a) Male, b) Female.

Fig. 3. Aristobia reticulator, head, anterior view.

Figs. 4–5. Aristobia reticulator. 4) Vertex and pronotum; 5) Antenna with an enlarged view of third segment.

Fig. 6. Aristobia reticulator, thorax, ventral view showing coxal cavities, episterna, and epimera.

Fig. 7. Aristobia reticulator, protarsal segments. a) Dorsal view, b) Ventral view, c) Lateral view.

Fig. 8. Aristobia reticulator, abdominal sternites, male and female.

Fig. 1. Map showing distribution range of Aristobia reticulator in the Asian-Pacific region and known localities in the states of northeastern India.