Dima xiaolongi Ruan, Kundrata & Qiu, 2018

Ruan, Yongying, Kundrata, Robin, Sormova, Eliska, Qiu, Lu, Zhang, Mengna & Jiang, Shihong, 2018, Description of two new species of Dima Charpentier, 1825 from China (Coleoptera: Elateridae: Dendrometrinae), Zootaxa 4526 (4), pp. 589-599 : 594-597

Dima xiaolongi Ruan, Kundrata & Qiu sp. nov.

( Figs. 4–6 )

Type locality: China, Hunan Prov., Bao-jing .

Etymology: This species is named after the collector of the holotype, Mr. Xiaolong Wang.

Distribution: China (Hunan Province).

Diagnosis: This species is rather distinct in Dima species by the following combination of characters: pronotum strongly convex from lateral view; mesoventrite and mesanepisternum with relatively small procoxal rests; elytral base narrowed; punctures on elytra conspicuously enlarged, interstria VI forming a prominent ridge; male genitalia with median lobe robust, much longer than parameres, with numerous minute spines on the ventral surface.

D. xiaolongi Ruan, Kundrata & Qiu sp. nov. resembles the most D. tianmuensis from Zhejiang, China ( Qiu et al. 2018). Both species share similar habitus, coloration, general shape of pronotum and mesoventrite, and ventrally serrate median lobe. However, D. xiaolongi Ruan, Kundrata & Qiu sp. nov. has denser pronotal punctation, longer posterior pronotal angles, more transverse metacoxal plate, median lobe relatively longer with respect to paramere, without basal struts, and differently shaped hook-like structures on paramere ( Figs 4 A–D, 5C– D).

D. xiaolongi Ruan, Kundrata & Qiu sp. nov. also resembles D. guizhouensis Ruan, Kundrata & Qiu sp. nov. in the relatively long elytra with ridge-like interstria VI. However, it can be easily distinguished from the latter by the chestnut brown coloration and divergent posterior pronotal angles.

Description (male, holotype): Body elongate-oval, obviously constricted near posterior angles of pronotum and base of elytra; pronotum strongly convex from lateral view. Head, antennae, scutellar shield, and ventral surface of pro- and mesothorax chestnut brown; pronotum chestnut brown, with anterior margin brown and posterior angles yellowish brown; elytra chestnut brown, with lateral margins and suture yellowish to reddish brown; legs yellow, somewhat yellowish brown near knee joint; abdominal ventrites yellowish brown. Surface of body clothed with golden, semi-erect pubescence; two types of pubescence present throughout the body (i.e., long hairs and shorter ones), more conspicuous on elytra (elytra with longer hairs light brown and shorter ones golden).

Body length: 6.90 mm. Body width (measured across the widest area of elytra): 2.75 mm. Width (measured across the widest area) of pronotum: 2.17 mm. Pronotum width to length (measured along midline, excluding posterior angles) ratio: 1.30. Ratio of pronotum width (measured in widest place) to distance between posterior angles: 1.18. Elytron length to width ratio: 3.45. Length of elytron to length of pronotum (measured along middle) ratio: 2.83. Width of elytra at base (measured at lateral sides near humeri) to maximum width of elytra ratio: 0.70.

Head ( Figs. 5 A–B, 6A–B) flattened, prognathous; chestnut brown, frontal carina above antennae yellowish brown. Surface of frons and vertex uneven, longitudinally impressed along middle, covered with sparse, small and partly irregular punctures; Anterior end of frons obviously bends downwards. Frontal carina absent in middle, sharp and prominently raised at sides above antennal insertions. Surface of carina smooth and shiny, lacking punctures on lateral sides above antennae. Mandible extending anteriorly; maxillary palpus moderately long, apical palpomere wide and long, hatchet-shaped. Antenna long, extending beyond middle of elytra; first antennomere extremely robust, second small, remaining antennomeres slender and elongate, last antennomere narrowly rounded at apex. Distance between eyes to transverse diameter of eye ratio: 3.35. Length of antenna to that of body ratio: 0.85. Proportions of antennomere lengths as follows: 100: 53: 83: 88: 98: 96: 95: 93: 97: 91: 120.

Pronotum ( Fig. 5D ) strongly convex from lateral view; lateral sides evenly convex before posterior angles, strongly constricted at base of posterior angles; posterior angles acute at apex, prominently divergent. Anterior angles weak, somewhat sharp from dorsal view, producing antero-laterally. Pronotal surface covered with small and close punctures, intervals between punctures about 2–3 times as the diameter of a puncture. Punctures dense on disc and anterior margin, sparse near lateral margins, nearly absent near hind margin. Basal margin sinuate, simple, without any groove or indentation. Prosternal process with length about twice as long as proxocal diameter, abruptly narrowed near apex ( Fig. 6D ). Scutellar shield ( Fig. 5E ) elliptic, widest near middle, width to length ratio: 1.24; disc very slightly convex; surface smooth, with punctures barely visible. Mesoventrite ( Fig. 6 C–E) with straight lateral sides; anterior extension slightly protruding forward, apex moderately emarginate at middle; procoxal rests on anterior edge relatively small; mesosternal cavity elongate, shallow, widened basally. Mesanepisternum with relatively small lateral extensions of procoxal rests. Ventral surface covered with dense and coarse punctures with interspaces smooth. Hind wings and humeral calli absent. Elytra narrow and long, widest near middle; sides convex, apex not truncate. Elytral surface with prominent longitudinal carinae. Circular and enlarged punctures present along elytral striae, much stronger and larger in lateral sides than medially. Interstriae slightly convex, covered with minute and distant punctures. Interstria VI narrow, forming prominent ridge; sides of elytra strongly bent downwards behind ridge. Legs long and slender. Ratio of lengths of metatarsomeres I–IV: 1.00: 0.64: 0.50: 0.50. Apex of tarsomeres III and IV with prominent lobe.

Abdominal tergite IX semi-oval, apical margin strongly incised at middle, v-shaped; tergite X small, hidden beneath tergite IX, semi-oval, with apical margin more or less straight ( Fig. 5F ). Abdominal sternite X ( Fig. 5G ) elongate, distal portion covered with setae; distal end wide, straight at middle, with rounded sides. Male genitalia ( Fig. 4 B–D) trilobate; median lobe considerably longer than parameres, without basal struts; its ventral surface with multiple minute spines. Paramere slender, slightly sinuate along length, apex acute, lateral (outer) side forming a sharp hook near distal fourth. Phallobase small, short, u-shaped.

Type material: Holotype: ♂ ( IZCAS), labels: 1) Hunan Prov., Bao-jing, Mao-gou-zhen, Xiaolong Wang leg., 2017. V.28; 2 ) Holotype Dima xiaolongi n. sp. Des. Ruan, Kundrata & Qiu 2018.

Figures

FIGURE 4. Dima xiaolongi Ruan, Kundrata & Qiu sp. nov. (holotype). A: habitus, dorsal view. B: male genitalia, dorsal view. C: male genitalia, lateral view. D: male genitalia, ventral view. E: habitus, lateral view. F: habitus, ventral view.

FIGURE 5. Dima xiaolongi Ruan, Kundrata & Qiu sp. nov. (holotype). A: head, dorsal view. B: mouthparts, fronto-ventral view, showing apical maxillary palpus. C: left metacoxal plate, ventral view. D: pronotum, dorsal view. E: scutellar shield, dorsal view. F: abdominal tergites IX– X, dorsal view. G: abdominal sternite IX, dorsal view.

FIGURE 6. Dima xiaolongi Ruan, Kundrata & Qiu sp. nov. A: head, fronto-dorsal view (holotype). B: head, fronto-lateral view (holotype). C: prosternal process and mesoventrite, lateral view (holotype). D: mesoventrite, ventral view (holotype). E: part of mesoventrite, ventral-lateral view (holotype).