Trichiorhyssemus immaturus Minkina, 2022

Minkina, Łukasz, 2022, Studies on subfamily Aphodiinae (Coleoptera: Scarabaeoidea: Scarabaeidae) with description of three new species from the genera Agrilinus Mulsant & Rey, 1869 Gilletianus Balthasar, 1933 and Trichiorhyssemus Clouët, 1901, Zootaxa 5162 (3), pp. 223-242 : 234-236

Trichiorhyssemus immaturus Minkina , new species

( Figs 13–14 , 27–29 , 34–35 )

Type locality. China, Prov. Hebei, Yongnian .

Type material. Holotype (♀): “ China, Prov. Hebei / Yongnian / vi.-xi.1995 / leg. Shuigiang Li ”.

Description of the holotype, female. Dorsum ( Fig. 27 ). Body length of holotype 2.9 mm, distinctly convex, elongate, paralel-sided, somewhat oval, almost wholy mat, distinctly macrosetose on head (sparsely), pronotum (quite densely) and elytra (densely); reddish-brown with legs and antennae, and border parts of body somewhat lighter.

Head ( Fig. 13 ) relatively large, quite subhexagonal, distinctly convex, strongly processed foreward, very distinctly mat in basal 1/3, moderately mat in apical 2/3, with distinct microreticulation. Clypeus gently bordered, distinctly, widely sinuate anteriorly, with sides subangulate, latter very widely rounded till the border with genae, clypeal border without macrosetae. Genae distinctly produced outward to form a straight line at the clypeal border; clypeus with very distinct, straight, long macrosetation. Granules on clypeus rather regularly distributed, not so coarse, dense in basal half, relatively sparse in apical half. Clypeus in basal part covered by granules with erect short and relatively thin macrosetae. There are no oblique ridges.

Epipharynx ( Fig. 34 ) transverse, with sides rounded, anterior margin truncate, somewhat outwardly produced on each side of corypha. Corypha with only few very short celtes, visible above of anterior margin. Acanthopariae, acropariae, prophobae, adelochaetae without chaetae; chaetopariae with dense belt of very thick, very long chaetae which almost reach epitorma; chaetopediae with relatively sparse, thick and long chaetae. Epitorma somewhat transverse-ovaly-shaped. Tormae short.

Pronotum ( Fig. 14 ) distinctly convex, distinctly transverse, as wide as the base of elytra, widest in the middle, matt, with tops of granules and bottom of punctures shiny. Anterior angles widely rounded, sides very weakly sinuate before hind angles, base widely rounded before hind angles. Anteriorly not bordered, anterior angles distinctly, but rather not widely deplanate, sides not bordered, base bordered by a shallow groove. Sides and base with yellowish, very thick, druseform macrosetae on its border ( Fig. 39 ). First pronotal ridge broken into discrete granules. Second to fifth ridges very weakly developed, very low, on its surface there are relatively small and relatively sparsely developed granules and because of it all ridges at first glance looks like broken. First transverse furrow with very small, variable in size and shape granules. The rest of furrows with distinct, very dense, variable in shape punctures from which errect moderately thick, quite short, somewhat club-shaped macrosetae. Punctures largest in the middle of posterior longitudinal furrow.

Scutellum small, triangular, somewhat shiny, with very dense, very fine, quite deep punctures, without microreticulation.

Base of elytra weakly bordered. Elytra elongate, convex, parallel, intervals mat with distinct microreticulation, striae shiny, with distinct, moderately large humeral denticles; with ten striae and ten intervals. Striae deep, distinctly, quite densely punctate. Intervals not so distinctly convex, with two rows of granules. Internal row with smaller granules bearing very thick, quite long, somewhat club-shaped macrosetae. External row with much larger granules – however against the background of the genus are relatively small, highest in basal part, becoming much lower and smaller till the apex; in apical third granules becoming shallower than width of striae, or just disappears on some intervals. External intervals with relatively lower and smaller granules than internal.

Pygidium with similar punctation, with six erected, thin, long macrosetae.

Legs. Profemora anteriorly and basaly distinctly bordered, meso- and metafemora shallowly bordered only basaly; profemora mat with distinct microreticulation, meso- and metafemora shiny, with very weak microreticulation; femora coarsely and densely punctate, all punctures with eracted thick, moderately long, straight macrosetae. Protibiae distinctly tridentate laterally, proximally not serrulate; dorsal side smooth, shiny, with few very fine punctures; apical spur quite long, quite slender, weakly downwardly and inwardly bent, with acute apex. Metatibiae superior apical spur distinctly shorter than basimetatarsomere, latter as long as next two metatarsomeres combined. Claws short, thin, distinctly arcuate.

Macropterous.

Venter ( Fig. 28 ). Meso-metaventral plate shiny, convex, with distinct, quite deep, long, thin longitudinal line in the middle; surface with very fine, very sparse punctures; on sides with fuzzy, somewhat cross-liked structure. Abdominal ventrites mat, anteriorly weakly fluted, with distinct microreticulation, with blurred zig-zag lines nearby the middle; very finely, very densely punctate.

Etymology. Name of new species comes from latin: “immaturus, -a, -um” which means immature. Name “immature” is proposed because of presence of suppressed structures of pronotum and elytra.

Differential diagnosis. Because of the lack of an oblique ridge on its head the newly described species can be classified to the genus Neotrichiorhyssemus , however it can be easily distinguished from all known species of this genus by: much lower tubercles of elytral intervals, which becomes smaller and lower towards the apex and on the sides, much lower and less developed transverse furrows of pronotum which are observed rather like separate tubercles than continuous structure and much sparser and finer punctation of meso-metaventral plate. On the other hand within the genus Trichiorhyssemus there are three similar species: T. kitayamai Ochi, Kawahara & Kawai, 2001 , T. hatakei Ochi, Kawahara & Inagaki, 2019 and T. taiwanus Ochi, Masumoto & Lee, 2015 , because of structure and size of tubercles on elytral intervals. Despite of occurrence of oblique ridge on head among all of them identification is not so easy because that ridge in all of them can be very poorly visible or just reduced in some specimens. For separation all mentioned species refer Table 2 .

It is interesting is that, on the border of sides and base of pronotum newly described species has characteristic druseform macrosetae ( Fig. 35 ). This shape of macrosetae was not observed in any known Trichiorhyssemus and Neotrichiorhyssemus but may it be overlooked. Somewhat similar macrosetae was reported by Rakovič & Král (1997) in the genus Messyrhus Rakovič & Král, 1997 .

Figures

FIGURES 13–20. Heads and pronotum. 13, Trichiorhyssemus immaturus Minkina, new species, holotype, female, head; 14, T. immaturus Minkina, new species, holotype, female, pronotum; 15, Agrilinus matusiaki Minkina, new species, holotype, male, head; 16, Agrilinus inexspectatus (Balthasar, 1935), male, head; 17, Agrilinus striatus (Schmidt, 1910), male, head; 18, Carinaulus meghalayensis (Červenka, 2000), male, head; 19, Gilletianus miurai Minkina, new species, holotype, male, head; 20, Gilletianus sundainsulanus Ochi, Kon & Kawahara, 2014, male, head.

FIGURES 27–29. Trichiorhyssemus immaturus Minkina, new species. 27, habitus, holotype, female, dorsal view; 28, habitus, holotype, female, ventral view; 29, habitus, holotype, female, lateral view.

FIGURES 30–35. Details of the morphology. 30–32, Agrilinus matusiaki Minkina, new species, holotype, male: 30, aedeagus, lateral view; 31, aedeagus, dorsal view; 32, epipharynx.33, Gilletianus miurai Minkina, new species, holotype,male, epipharynx; 34, Trichiorhyssemus immaturus Minkina, new species, holotype, female, epipharynx; 35, T. immaturus Minkina, new species, holotype, female, druseform macrosetae on border of pronotum.

FIGURES 36–41. Aedeagi. 36–38, Gilletianus miurai Minkina, new species, holotype: 36, aedeagus, dorsal view; 37, aedeagus, lateral view; 38, apex of parameres, lateral view. 39–41, Gilletianus sundainsulanus Ochi, Kon & Kawahara, 2014: 39, aedeagus, lateral view; 40, aedeagus, dorsal view; 41, apex of parameres, lateral view.