Termitotrox icarus, Kakizoe & Liang & Myint & Maruyama, 2020

Kakizoe, Showtaro, Liang, Wei-Ren, Myint, Khin Mar & Maruyama, Munetoshi, 2020, Termitotrox icarus sp. nov. (Coleoptera: Scarabaeidae): a new termitophilous beetle from Myanmar with observations of carrying behavior by host termites, Acta Entomologica Musei Nationalis Pragae 60 (2), pp. 427-436 : 429-433

Termitotrox icarus sp. nov.

( Figs 3–13 , 17 , 21, 22 )

Type material. HOLOTYPE: ♂ (deposited in NSMT collection), Myanmar, Nay Pyi Taw, Zeya Thiri Township , (alt. 120 m), 19.77°N, 96.31°E, 28–29 VII 2019, S. Kakizoe, W.-R. Liang, and K. M. Myint leg. (from the nests of Odontotermes proformosanus ) . PA*©ATYPE S: 20♂♂ 20 ♀♀, and 1256 unsexed specimens: MYANMAR: NAY PY] TAW: same data as holotype T 13 unsexed specimens: same data as holotype but 27.vii.2019 and collected from different termite colony of same termite species than the 28–29.vii.2019 series. Paratypes will be distributed to CMN, FRINM, KUM, MNHN, NCHU, NHMUK, NMPC, NSMT, and SKC.

Diagnosis. This species is similar to T. cupido and T. venus in having wing-shaped trichomes on the elytral base, but it is easily distinguished from these species because of the following combination of characters: a) the more elongate habitus shape in dorsal view, b) the basomedian section of pronotum not protruding backwards, c) a pair of distinct costae on the pronotal basomedian section are strongly developed, d) a median costa on anterior pronotal margin is strongly developed, e) the elytral striae narrower than interstriae, e) the lack of trichomes at the base of elytral sutural stria, and f) a size intermediate between the two aforementioned species (1.5–1.9 mm) vs. 1.2 mm in T. cupido and 2.4 mm in T. venus .

Description. Male (holotype). General color ( Figs 3–8 ) uniformly reddish-brown, matt, body length 1.75 mm. Head ( Figs 3–7 ). Surface generally evenly convex, clypeofrontal suture imbricate apart from a slight callosity in the middle (at high magnification). Lateral margins of head entirely, finely marginate. Clypeal outline evenly rounded over entire length. Clypeofrontal border at suture strongly grooved except for a callosity, straight to genal tip. Clypeofrons reddish brown, glabrous, distinctly, moderately punctate, with few small deep elongate punctures. Vertex with 10 elongate deep punctures (in dorsal view). Genae obtusely angular (in dorsal view)T genal surface depressed, distinctly imbricate. Antennae ( Fig. 4 ) yellowish-brown, 9-segmented, including the 3-segmented club. Compound eyes absent. Maxillae small, longer than wide T galeae toothed distally T basistipites and palpifer with long setae on lateral side. Maxillary palpus 4-segmented and well developed T segment I small, bent outwards T segment II about 3 times as long as segment I T segment III small, about 2 times as long as segment I, slightly bent inwards T segment IV large, approximately 1.5 times as long as segment II T numerous digitiform sensillae present on ventrolateral side of proximal half of segment IV. Mandibles asymmetrical, pointed apically, numerous serrate ridges on molar surface. Epipharynx ( Fig. 9 ) with anterior margin almost straight, epitorma almost indistinct, pedia almost glabrous, chaetoparinae and adelochaetae very strong and elongate. Pronotum ( Figs 3, 5, 7 ). Prothorax dark brown, as wide as elytra, sides (in dorsal view) almost straight over anterior 2/3. Anterolateral lobes obtusely angular (in dorsal view), edge slightly projecting downward (forming side of anterolateral propectoral cavity). Pronotal sides steeply declivous. Posterolateral sections of pronotum rounded. Base of pronotum evenly rounded, immarginate T basolateral area with few narrow ridges and grooves. Pronotal surface glabrous except for costae. Costae densely punctate, microsetose, intercostal sulci distinctly wrinkled. Central depression deep T surface winkled. Pronotal pattern of longitudinal costae as follows: median costa at anterior margin broad, becoming indistinct around anterior 1/4T basomedian section narrow, surface winkled, strongly concave, with a pair of distinct costae. Central depression posterolaterally delimited by extra grooves along paramedian costae. Paramedian costae narrow, distinct, posteriorly interrupted by deep sulcus. Sublateral costae anteriorly broad, distinct, tapering posteriad to about 1/5 of pronotal length, reaching paramedian costa. Lateral costae anteriorly broad, distinct, extending from anterolateral lobe caudad, tapering to base of pronotum. Marginal costae anteriorly broad, evenly curved, tapering to base of pronotum. Elytra ( Figs 3, 5, 7 , 10). Elytra, elongate, strongly convex dorsally, as high as pronotum, reddish brown, with 9 interstriae and intervening striae, and with short trichomes at base of interstriae 4–6 forming wing-shaped patches. Humeral and apical elytral calli absent T apicosutural angle nearly rectangular, slightly protruding. Epipleuron wide. Elytral striae distinct, deeply impressed, with transverse weak costae forming quadrate cells present from base to apex. Discal interstrial costae generally broadly rounded (in cross-section), surface with dense, scattered micropunctations, microsetose. Elytral pattern of interstrial costae as follows: interstria 1 (next to suture) narrow, almost rectilinear T interstria 2 tapering in front, stopping at basal 1/5T interstria 3 complete, slightly narrow at middle, weakly protruding in front T interstria 4 complete, narrow T interstriae 5 and 6 complete, strongly developed T interstria 7 complete, basally broad, strongly developed T interstria 8 complete, strongly developed T interstriae 9 and 10 apparently fused together. Apterous ( Fig. 8 ). Scutellum notably small, invisible in dorsal view. Prosternum ( Figs 4, 6 ). Anterolateral part of propectus deeply excavate. Preprosternal apophysis notably small, invisible in ventral view. Propectus glabrous, dark brown. Posterolateral areas of propectus narrow, with two distinct grooves in each area. Postprosternal surface reddish brown, glabrous, imbricate flattened. Mesoventrite ( Figs 4, 6 ). Surface reddish brown, glabrous, imbricate, flattened, moderately micropunctate. Mesoventrite with distinct trapezoidal shaped groove bordering mesocoxae T anterior side distinct, slightly curved T lateral sides notably broad, slightly curved T posterior side between posterior edges of mesocoxae distinct, straight, not completely reaching mesocoxae. Metaventrite ( Figs 4, 6 ). Metaventrite reddish brown, glabrous, imbricate, flattened, moderately micropunctate, with fine median and perimarginal grooves all around. Abdomen ( Figs 4, 6 , 11 ). Venter with 5 fairly sclerotized abdominal ventrites, all reddish brown, glabrous, imbricate, moderately micropunctate T abdominal ventrites 2 and 3 with series of distinct, short, elongate punctures along base at middle T abdominal ventrite 4 without series of distinct elongate punctures at middle T abdominal ventrite 5 with series of distinct, short, elongate punctures along base over entire length in anterior half. Pygidium reddish brown, glabrous, generally convex, moderately micropunctate T base broadly marginate. Propygidium ( Fig. 12 ) with basal longitudinal groove. Legs ( Figs 3–7 ). Procoxae protuberant. Profemora brown, underside glabrous, imbricate, moderately micropunctate T outline broadly elliptical, emarginate distally. Protibiae pale brown, broad, sparsely and shortly setose, microsculpture poorly pronounced T shape strongly complanate with 2 external denticles, no basal serration T apex oblique-sinuate, transverse, with distinct apico-internal spine T internal side strongly dilated from slender base. Protarsi pentamerous, two times longer than width of tibial apex, slender, yellowish brown T segment 1 inserted in fine groove, as long as segments 2–4 combined. Anterior claws normal, symmetrical. Mesocoxae dark brown, widely separated, slightly divergent anteriad. Mesofemora reddish brown, broadly elliptic in outline, distally emarginate, surface moderately micropunctate, glabrous, imbricate. Mesotibiae reddish brown, with several setae, broad, abruptly dilated near base, nearly parallel-sided from apex, edges entire T tibial apex slightly emarginate, with pair of acuminate apico-internal spurs, external one long, slightly curved, internal one short, straight T upper side of mesotibia with fine longitudinal ridge near outer edge, few weak costae at basal half, underside with two fine sinuate ridges from base to apico-internal section T with long setae around apical half. Metatibiae similar to mesotibia, but shorter and gently dilated apically, with apex shallowly emarginate. Meso- and metatarsi reddish brown, compacted-complanate, segments 1–4 short. Length of outer apical spur of metatibia 1/4 length of metatibia, reaching base of tarsal segment 5. Middle and hind claws normal, symmetrical. Aedeagus ( Fig. 13 ) symmetrical, length of aedeagus 0.71 mm (40.5M of body lengh). Phallobase elongate, cylindrical. Parameres short, almost half-length of basal piece. Apophyses of parameres long, almost same length of phallobase. Median lobe weakly sclerotized apically, with long apophyses (temones) almost same length of phallobase T anterior angle acute.

Female. Secondary sexual dimorphism not appreciable.

Measurements (N = 18). Body length 1.51–1.88 (1.69±0.100)T maximum width of head 0.56–0.68 (0.64±0.030)T median dorsal length of pronotum 0.66–0.76 (0.71±0.030), maximum width 0.73–0.85 (0.78±0.032)T sutural length of elytra 0.73–0.95 (0.81±0.052), maximum width 0.73–0.85 (0.79±0.036).

Etymology. In Greek mythology, Icarus was the son of Daedalus. He is famous for having approached the sun with wings made of feathers and wax, which melted and gradually became smaller, thus eventually causing his falling into the sea. The name refers to the smaller elytral wing-shaped trichomes compared to the other known species of the genus having wing-shaped trichomes (i.e., Termitotrox cupido and T. venus ). Noun in apposition.

Symbiotic host. Odontotermes proformosanus Ahmad, 1965 (identified by Dr. Yoko Takematsu).

Remarks. In some female specimens, we observed a single giant egg ( Figs 21 and 22 ). We randomly chose 20 females and dissected them, 17 of them had one single egg while the others did not bear any egg.

Collecting circumstances. We found more than 1000 T. icarus sp. nov. individuals in the fungus garden chambers of Odontotermes proformosanus . We found T. icarus sp. nov. individuals from two colonies of Odontotermes proformosanus . Almost all individuals (>99M) were collected from a single colony. The colonies were located on the edge of a small secondary forest, and the soil was laterite. Collection season (July) was the rainy season. We carefully examined the walls of the fungus garden chambers and the inside of the fungus garden combs, but we did not find Termitotrox eggs, larvae, or pupae. We recorded the location from which adult Termitotrox beetles were collected in the 44 fungus garden chambers surveyed on July 29, 2019. The analysis yielded no significant difference in the mean number of individuals collected “on the chamber wall” and “inside the fungus garden” (Wilcoxon signed rank test, V = 446, P = 0.1558, Fig. 20 ).

Behavioral observations. In laboratory-based observations, we recorded multiple instances of host termite minor workers carrying T. icarus sp. nov. individuals with their mandibles ( Figs 18 and 19 , and S1). The beetle constantly exposed its antennae and legs and frequently moved its legs. In each instance, the carrying period was about 5 minutes. This behavior was also observed multiple times in the field. However, nutrient exchange (trophallaxis) between the termite and beetle was not observed during either field or laboratory observations.

Distribution. Central Myanmar.

Figures

Figs 3–8. Habitus of Termitotrox icarus sp. nov. (holotype and paratypes). 3 – holotype male, dorsal viewT 4 – paratype male, ventral viewT 5 – paratype female, dorsal viewT 6 – ditto, ventral viewT 7 – holotype male, antero-lateral viewT 8 – paratype male, dorsal view (elytra removed). Scale bar = 1.0 mm.

Figs 9–13. Body parts of Termitotrox icarus sp. nov. (paratype male). 9 – epipharynx, ventral viewT 10 – elytra, dorsal viewT 11 – abdomen, ventral viewT 12 – pygidium, postero-lateral viewT 13 – aedeagus, dorsal view. Scale bars: 0.05 mm (Fig. 9)T 0.20 mm (Fig. 10)T 0.10 mm (Figs 11–13).

Figs 14–17. Habitat of Termitotrox icarus sp. nov. 14–15 – termite mound of host termite Odontotermes proformosanus Ahmad, 1965T 16 – a fungus garden chamber of host termiteT 17 – alive specimen of Termitotrox icarus sp. nov. walking on the wall of fungus garden chamber.

Figs 21–22. Single large egg in a female Termitotrox icarus sp. nov. (21 – dorsal viewT 22 – lateral view).

Fig. 20. The number of Termitotrox icarus sp. nov. found on the wall of chamber or inside the fungus garden comb. There was no significant difference in the number of individuals between the two locations (Wil- coxon signed rank test, V = 446, P = 0.1558).

Figs 18–19. Carrying behavior by host termite Odontotermes proformosanus Ahmad, 1965 to Termitotrox icarus sp. nov. (observed in laboratory).