Agathidium (Agathidium) pilulum, Švec, 2022

Švec, Zdeněk, 2022, Leiodidae (Coleoptera) of the Hainan Island with new faunistic records from China and with notes on the unique body modifications in the genus Agathidium, Acta Entomologica Musei Nationalis Pragae (Acta. Ent. Mus. Natl. Pragae) 62 (1), pp. 155-164 : 157-158

Agathidium (Agathidium) pilulum sp. nov.

( Figs 1–4 , 13 )

Type locality. China, Hainan Island, Limushan Mts, 19°10.5–10.9′N, 109°44–45′E, 650– 900 m.

Type material. Hඈඅඈඍඒඉൾ: J, “ CHINA: Hainan isl. [MF 19] / Limushan Mts, mountains / above first admin.centre / 19°10.5–10.9′N 109°44–45′E/ 650-900 m, 6.v.2011, Fikáček // sifting small accumula- / tions of moist leaf litter along / and on the trail in secondary / forest partly with Cyathea and / bamboo” ( NMPC). Pൺඋൺඍඒඉൾඌ: 5 JJ 2 ♀♀, same data as holotype ( NMPC, ZSPC).

Description. Length of body in holotype 1.9 mm, head 0.3 mm, pronotum 0.7 mm, elytra 0.9 mm, antenna 0.6 mm, aedeagus 0.74 mm. Maximum width of head 0.8 mm, pronotum 1.2 mm, elytra 1.2 mm.

Body short oval. Pronotum chestnut, elytra dark chestnut with feebly expressed reddish narrow strip along suture, head lighter than pronotum. Legs and antennae yellow-red with A9 and A10 a little darker. Ventral surface yellow-brown. Dorsum punctured, without microsculpture. Sutural striae absent; femoral lines developed, supraocular carina raised anteriorly.

Head. Maximum width of head far before posterior margin of eyes. Eyes parabola slice-shaped. Supraocular carina low posteriorly, raised anteriorly. Subocular line not developed. Clypeus straight, feebly emarginate, clypeal line lacking ( Fig. 13 ). Antennomere 3 distinctly longer than A2 (A3/A2 = 1.5). Ratio of lengths of A2–A11 (A2 = 1.0): 1.0-1.5-0.8-0.6-0.5-0.5-0.6-1.3-1.1-2.0. Ratio of widths of A2–A11 (A2 = 1.0): 1.0-0.5-0.7-0.8-1.0-1.2- 1.3-1.7-1.8-1.8. Ratio of W/L of A2–A11: 0.8-0.3-0.7- 1.0-1.5-1.8-1.6-1.0-1.2-0.7. Surface of head smooth with very fine very sparse punctures separated by more than 10 times their own diameters.

Pronotum. Lateral outline with shortly rounded angle in lateral view (as in Fig. 3 ). Puncturation sparse and fine, similar to that on head with punctures separated by about 10 or even more times their own diameter.

Elytra widest at lateral angles, then evenly roundly narrowed posteriorly. Elytral margin straight behind lateral angles in lateral view ( Fig. 3 ). Lateral elytral channel as narrow behind lateral angles as in basal part. Puncturation similar to that on head but punctures a little stronger, separated by about 6–10 or more times their own diameter. Sutural striae not developed.

Legs. Tarsi slim, all tibiae slim, metafemora simple, without specific characters. Tarsal formula: 5-5- 4 in male.

Mesoventrite. Posterior part subconcave. Anterior part raised with longitudinal carina. Lateral lines not developed.

Metaventrite moderately developed. Femoral lines developed, shortened for half of their possible length. Fovea located in middle of posterior margin of metaventrite equipped with bush of erect setae.

Membranous wings developed.

Genitalia. Basal part of median lobe narrow ring-shaped of type C. Shape of median lobe apex resembles skittle pin in dorsal view. Apical part of median lobe first contracted, emarginated laterally, then feebly widened. Operculum egg-shaped. Parameres narrowed apically; each with two short and fine setae (aedeagus as in Figs 1, 2 ).

Variation and sexual dimorphism. Length of body is 1.8–2.0 mm in the type series. The ratio of A3/A2 varies between 1.3–1.6. Tarsal formula 5-4- 4 in female. Spermatheca with pear-shaped basal part and simply bowed distal thin part ( Fig. 4 ). Length of spermatheca 0.13 mm. Differential diagnosis. Agathidium (Agathidium) pilulum sp. nov. as well as the species it is compared with bellow habitually belong to the A. madurense species group sensu AඇGൾඅංඇං (1993) due to raised anterior part of the supraocular carina. The new species stands closest to A. (Agathidium) occultum Angelini & De Marzo, 1998 from China, Yunnan (AඇGൾඅංඇං & Dൾ Mൺඋඓඈ 1998b) as both species are similar in the shape of body that is broadly oval, in the shape of straight, feebly emarginated clypeus, in the eyes that are parabola slice-shaped and in the raised anterolateral bead of head. Colour of the antenna is yellow-red with A9 and A10 a little darker in both species. Both compared species possess A3 distinctly longer than A2 and also slim tibiae. Sutural stria is missing in both species. Agathidium pilulum sp. nov. differs from A. occultum in the specific shape of its median lobe that is simply cylindrical with broadly rounded tip in A. occultum . Agathidium pilulum sp. nov. can be also compared to A. (A.) alesi Angelini & De Marzo, 1998 from Taiwan (AඇGൾඅංඇං & Dൾ Mൺඋඓඈ 1998a), that also belongs to the A. madurense species group, having similar skittle pin-shaped apical part of the median lobe. The new species differs from A. alesi in distinctly smaller body (1.8–2.0 mm), while the length of body is 3.0– 4.1 mm in A. alesi . Antenna is bicolored in A. pilulum sp. nov., antenna in A. alesi is unicolorous, light. Posterior femora are straight on their hind margin, while the same are toothed in A. alesi . Moreover, the apex of the tegmen is distinctly bent upwards and paramera is shorter in A. alesi compared with A. pilulum sp. nov. Spermatheca is similar in its shape in all the compared species; basal part of spermatheca is pear-shaped in A. pilulum sp. nov. while the same is subcylindrical in A. occultum and A. alesi . Etymology. The name of the new species draws the attention to the globular shape of the apex of the median lobe. Therefore the name is derived from the Latin word pilula (= globule in English). Noun in apposition.

Figures

Figs 1–8. 1, 2, 6, 7 – aedeagus laterally and tip of aedeagus dorsally. 3, 5 – lateral view of body. 4, 8 – spermatheca. 1–4 – Agathidium (Agathidium) pilulum sp. nov.; 5–8 – Agathidium (Macroceble) cornigerum sp. nov. Scale bars in Figs 1, 2, 4, 6, 7, 8 = 0.1 mm; 3, 5 = 0.5 mm.

Figs 13–16. 13, 15, 16 – head dorsally; 14 – head laterally. 13 – Agathidium (Agathidium) pilulum sp. nov.; 14, 16 – Agathidium (Macroceble) cornigerum sp. nov.; 15 – Agathidium (Macroceble) apiforme sp. nov.