Horniolus minutus, Szawaryn & Větrovec, 2020

Szawaryn, Karol & Větrovec, Jaroslav, 2020, A new species of Horniolus Weise with remarks on the systematic position of the genus (Coleoptera: Coccinellidae), Zootaxa 4861 (4), pp. 573-580 : 574-576

Horniolus minutus sp. nov.

Figs. 1 A–C, 2A–D, 3A–F

urn:lsid:zoobank.org:act:D688D63B-D556-453F-AD64-4DDB0A2DE9CC

Diagnosis. This species is similar in elytral maculation to H. hainanensis Chen & Ren , H. sororius Poorani , H. amamensis Miyatake and H. kyushuensis Miyatake , but H. hainanensis differs from H. minutus by having incomplete abdominal postcoxal lines, H. sororius by differently shaped male genitalia, and from the remaining two species H. minutus can be separated by the coarse punctation of the meso-, meta- and abdominal ventrites and the region on ventrite 1 surrounded by the abdominal postcoxal lines, and by the distinctly truncate posterior margin of ventrite 5. In general shape, the male genitalia of H. minutus resemble those of H. guimeti (Mulsant) and H. nigripes Miyatake , but both species have the penis guide subtriangularly shaped, not broadened in apical part as in the new species. From other species of Horniolus the new species can be separated by its elongate, parallel sided, and flattened, not spherical, body in lateral view.

Description. TL: 2.07 mm, TW: 1.19 mm, BH: 0.73 mm, TL/TW: 1.74, PL/PW: 0.47, EL/EW: 1.23, PW/EW: 0.81.

Body elongate, parallel sided, flattened, dorsum covered with black pubescence ( Figs. 1A, C ). Head reddish dark brown ( Figs. 1A , 2C ). Antennae and mouthparts light brown ( Fig. 2A ). Pronotum dark brown, scutellar shield black. Elytra black with four yellowish spots, first pair transverse, with undulated borders, parallel to elytral base, situated at anterior third of elytra; second pair smaller, located in apical part of elytra, not reaching suture and lateral margins ( Figs. 1A, C ). Ventrum dark brown. Legs light brown ( Fig. 1B ).

Head with fine frontal punctures, slightly larger than eye facets, 1.0–2.0 diameters apart. Clypeus short, expand- ed laterally, forming an eye canthus, slightly emarginate anteriorly, with complete border at anterior margin, covering antennal insertions from above ( Fig. 2C ). Labrum transverse, broadly rounded. Eyes finely faceted, interocular distance 0.6 times head width, with distinct interocular setae. Antenna consisting of 11 antennomeres, scape large, swollen, pedicel cylindrical, antennomeres 3–10 transverse, antennomere 11 small, transverse, shorter and narrower than antennomere 10, antennomeres 7–11 forming indistinct club. Terminal maxillary palpomere stout, securiform, weakly broadening apically, apical margin strongly obliquely truncate. Prementum truncate apically; mentum trapezoidal, emarginate anteriorly with lateral lobes, broadest in anterior part; submentum small, indistinct. Gula broad and long, with short gular sutures at base ( Fig. 2A ).

Pronotum transverse with anterior and lateral margins distinctly bordered, posterior margin without border. Lateral edges with a row of long stiff setae. Pronotal punctures same size as those on frons, 1.0–2.0 diameters apart. Prosternal carinae inverted Y-shaped with stem about ⅓ as long as arms, arms broadly separated, surface between arms smooth. Scutellar shield large, sub-triangular.

Surface of elytra with punctures larger than those on pronotum, separated by 1.0–2.0 diameters. Elytra elongate, parallel sided, with elytral epipleuron incomplete, reaching posterior margin of ventrite 1. Mesoventrite transverse, about twice as broad as its length, with anterior border distinctly raised and emarginate medially. Metaventrite large, metaventral postcoxcal lines rounded and complete laterally, joined medially, forming a transverse line ( Fig. 2B ). Discrimen visible in posterior half.

Legs stout with transverse trochanters, trochanters grooved for reception of apices of tibiae, trochantero-femoral joint oblique, femora broad, swollen, tibiae broadened with surfaces to accommodate tarsi in repose, without apical spurs; tarsi tetramerous, tarsomeres 1 and 2 lobed.

Abdominal postcoxal lines strongly recurved and complete laterally ( Fig. 2D ), reaching 4/5 length of abdominal ventrite 1. Ventrite 1 long, almost as long as ventrites 2–4 combined, ventrites 2–5 subequal in length. Abdominal ventrite 5 truncate apically in male ( Fig. 3A ), ventrite 6 slightly protruding apically ( Fig. 2D ), slightly emarginate ( Fig. 3B ), tergite VIII rounded. Genital segment as in Fig. 3C .

Male genitalia. Penis stout, evenly curved ( Fig. 3F ); penis capsule with long inner arm, outer arm reduced; apex of penis as in Fig. 3F . Tegmen with penis guide slightly shorter than parameres, distinctly broadened in apical third ( Figs. 3D, E ), then tapering gradually to blunt apex.

Female not known.

Type material. Holotype: male, THAILAND: 100 km NE of Bangkok Khao Yai N.P., leg. F. Pavel, 13– 15.12.2002. ( NMPC).

Distribution. Thailand. Known only from the holotype.

Etymology. The specific epithet refers to the small size of the newly described species.

Figures

FIGURE 1. Habitus of Horniolus species. A) H. minutus sp. nov., dorsal; B) H. minutus sp. nov., ventral; C) H. minutus sp. nov., lateral; D) H. hisamatsui Miyatake; E) H. vietnamicus Miyatake; F) H. sonduongensis Hoàng.

FIGURE 2. Horniolus minutus sp. nov. A) Head with mouthparts and prothorax, ventral; B) meso- and metaventrite; C) head, frontal; D) abdomen, ventral.

FIGURE 3. Abdomen and male terminalia and genitalia. Horniolus minutus sp. nov.: A) abdomen; B) adominal segment VIII; C) male genital segment; D) tegmen, lateral; E) tegmen, inner; F) penis, lateral. H. hisamatsui Miyatake: G) tegmen, lateral; H) tegmen, inner view; I) penis, lateral; J) abdomen. H. vietnamicus Miyatake: K) abdomen; L) tegmen, lateral; M) inner view; N) penis, lateral.