Phorocardius minutus Ruan & Douglas, 2020

Ruan, Yongying, Douglas, Hume B., Qiu, Lu, Chen, Xiaoqin & Jiang, Shihong, 2020, Revision of Chinese Phorocardius species (Coleoptera, Elateridae, Cardiophorinae), ZooKeys 993, pp. 47-120 : 47

6. Phorocardius minutus Ruan & Douglas sp. nov. Figs 12 , 13 , 23F , 24F , 25F

Type locality.

Inner Mongolia: Da-yin-zi, Linxi County ("Ta-Yngtse, Linsisien").

Etymology.

This species is named for its small body size.

Distribution.

China (Inner Mongolia).

Differential diagnosis.

Body length 5-7 mm. Prothorax: procoxal cavities open; prosternal process gradually narrowed posterad to ventral apex in ventral view, with apex narrowly rounded. Pterothorax: scutellar shield with posterior apex narrowly rounded. Tarsal claw with ventral apex smaller than dorsal apex. Male genitalia: paramere with apex pointed and bent laterad and ventrad, without preapical lateral expansion or apical mesal callus. Female unknown.

Phorocardius minutus Ruan & Douglas, sp. nov. is distinct for its small body size, color, and more robust appendages compared to other Chinese species. Its partly yellow elytra resemble P. flavistriolatus Ruan & Douglas, sp. nov., and P. comptus ( Candèze, 1860).

This species can be differentiated from P. flavistriolatus Ruan & Douglas, sp. nov. by the following characters: in P. minutus Ruan & Douglas, sp. nov., aedeagus with paramere apex claw-like, produced laterally; males are less than 6.3 mm in body length; and body brown, elytra yellow, with suture and lateral-basal edges near epipleura brown; while in P. flavistriolatus Ruan & Douglas, sp. nov., aedeagus with apex of paramere not claw like or produced laterally; males are longer than 7 mm; body black-brown; and elytra black-brown with two longitudinal yellow stripes.

P. minutus Ruan & Douglas, sp. nov. can be differentiated from P. comptus by the following characters: in P. minutus Ruan & Douglas, sp. nov., males are less than 6.3 mm in body length; and body brown, elytra yellow, with suture and lateral-basal edges near epipleura brown; while in P. comptus , males are longer than 7 mm; and body black, elytra black with two longitudinal yellow stripes.

Description.

(Based on all type specimens) Dorsum matt. Head brown, with mouthparts red-brown to pale brown. Antennae pale brown. Pronotum brown, with posterior edge dark brown. Scutellar shield brown. Elytra yellow, with suture and lateral-basal edges near epipleura brown. Ventral surfaces brown, including hypomera. Epipleura brown. Legs pale brown to brown. Body with yellow pubescence.

Measurements.

(based on all type specimens) Male body length 5.2-6.3 mm, width 1.6-2.2 mm. Body length to width ratio 2.9-3.2. Pronotal width to length ratio 1.1-1.2. Pronotum slightly narrower than elytra, Pronotal width to body width ratio 0.86-0.87. Elytral length to pronotal length ratio 2.7-2.9; elytron length to width ratio 3.9-4.3.

Head. Frons and vertex with interspaces between punctures 1-3 × average puncture diameter. In frontal view, edge of frontal carina convex. Antenna with apex extending slightly over posterior angle of pronotum. Distance between eyes to width of eye ratio 4.1-4.5. Antenna length to body length ratio 0.40-0.45; proportions of antennomere length as follows: 100 (scape); 66-70; 98-100; 88-95; 97-107; 97-110; 108-112; 110-115; 109-120; 104-110; 139-142.

Prothorax. Pronotum in dorsal view (Fig. 13A ): sides convex from anterior to near posterior fourth, concave on posterior fourth, widest near mid-length; posterior angles with lateral sides slightly and evenly convex; surface with interspaces between punctures 1-2 × average puncture diameter. In ventral view, ventral surface of prosternal process with sides carinate at basal half (not carinate at apical half), gradually narrow from anterior to posterior end, with apex narrowly rounded. In lateral view, prosternal process with ventral surface curved strongly dorsad, posterior end weakly concave (Fig. 24F , upper arrow). Procoxal cavities open.

Pterothorax (Figs 24F , 25F ). Mesepisternum in ventral view with antero-mesal angle broadly rounded (Fig. 25F , upper (green) arrow). Projections on posterior edge of mesosternum absent in ventral view (Fig. 25F , lower (red) arrow) and lateral view (Fig. 24F , lower (red) arrow). Scutellar shield: short, width to length ratio 0.85-0.94; anterolateral edges evenly convex; posterior apex narrowly rounded. Elytra: upper edge of epipleura with minute serrations.

Legs. Femora and tibiae thick. Length ratio of metatarsomeres I-V (excluding claws): 100; 66-76; 60-63; 45-48; 110-120. Claw with ventral apex much smaller than dorsal apex.

Abdomen. Lateral edges of visible abdominal ventrites I-V with minute serrations.

Male genitalia. Slender in ventral and lateral views. Median lobe in ventral view gradually narrowed from base to rounded apex. Median lobe in lateral view gently curved ventrad, apex rounded. Paramere in ventral view: wide, width 2-2.5 × median lobe width (measured across the mid-length of paramere and median lobe respectively), widest near apical third, abruptly narrowed near apex; apex pointed, bent laterally; preapical lateral expansion and apical mesal callus absent. Paramere in lateral view: robust, almost straight from base to mid-length; bent ventrad from mid-length to apex; apex pointed and facing ventrad, claw-like, but not hooked.

Female. Unknown.

Type material.

Holotype. ♂ (IZCAS), labels: 1) Manchoukuo, Ta-Yngtse (大营子), Linsisien (林西县), leg. E. Bourgault, VII.1940; 2) Phorocardius comptus Cand. Det. Siqin Ge; 3) Holotype Phorocardius minutus sp. nov. Des. Ruan et al., 2019.

Paratypes (3♂). 1♂ (IZCAS), labels: 1) Inner Mongolia, Ke-you-zhong-qi (科右中旗), stock farm, 1995.VII.15 [in Chinese]; 2) leg. Mingzhi Yang [in Chinese]; 3) Cardiopnorine; 4) Elateridae ; 5) Paratype Phorocardius minutus sp. nov. Des. Ruan et al., 2019. • 1♂ (SZPT), labels: 1) Inner Mongolia, Da-qing-gou (大青沟), Xiao-qing-hu, 19.VII.2013, leg. Kai Shi [in Chinese]; 2) Paratype Phorocardius minutus sp. nov. Des. Ruan et al., 2019. • 1♂ (SZPT), labels: 1) Inner Mongolia, Da-qing-gou (大青沟), Xiao-qing-hu, sweeping, 20.VII.2013, leg. Kai Shi [in Chinese]; 2) Paratype Phorocardius minutus sp. nov. Des. Ruan et al., 2019.

Remarks.

The aedeagus of one paratype collected from 'Ke-you-zhong-qi, Inner mongolia’ is slightly different from that of the holotype by being slender in ventral and lateral views (Fig. 11I, J ). However, all external characters of this individual (e.g., body color, shape and length, punctures on head and pronotum) are identical with the Holotype. The slight differences in the shape of aedeagus are treated as intraspecific variation here.

Previously, the genus Phorocardius was only known from the Oriental Region. The discovery of P. minutus Ruan & Douglas, sp. nov. from the Palearctic Region indicates that the members of this genus can survive in areas with freezing winter temperatures (in Ke-you-zhong-qi, Inner Mongolia, the minimum temperature is approximately -20 °C in January). Examination of female genitalia or phylogenetic studies would be useful to see how closely this species is related to other Phorocardius . The thick tibiae and ascendant prosternal process of this species are similar to many fossorial elaterids ( Douglas 2011), including many species with flightless females. Females of this species are currently unknown.

Phorocardius minutus Ruan & Douglas, sp. nov. is like Diocarphus solitarius (Fleutiaux, 1931) in the ventral apex of the tarsal claw is much smaller than the dorsal apex. However, P. minutus can be easily separated from Diocarphus by its open procoxal cavities and the pronotum without pronotal lateral carina.

Based on specimen information, this species inhabits low elevation areas (ca. 0-500 m) in Inner Mongolia, north China. This area is arid with temperate grassland and shrubland and cold winters. Known only from the Palearctic Region.

Figures

Figure 11. Phorocardius manuleatus Candeze (1888). A pronotum and scutellar shield, dorsal view B head, frontal view C punctation on disc of pronotum D punctation on vertex of head E color variation between four individuals; insets 2, 4, 6, 8 are the ventral views of 1, 3, 5, 7 F aedeagus, in dorsal view and lateral view, arrows indicating apices of parameres.

Figure 12. Phorocardius minutus Ruan & Douglas, sp. nov. A holotype, habitus, dorsal view, arrow indicating claw B paratype, habitus, ventral view, arrow indicating hypomeral hind edges C antennae of holotype, showing triangular antennomeres III-IV D-F aedeagus of holotype D dorsal view E ventral view, arrows indicating apices of parameres F lateral view, arrow indicating apices of parameres G, H aedeagus of paratype collected from Da-qing-gou, Inner Mongolia, ventral and lateral views I, J aedeagus of paratype collected from Ke-you-zhong-qi, Inner Mongolia, ventral and lateral views, arrows indicating apices of parameres.

Figure 13. Phorocardius minutus Ruan & Douglas, sp. nov. A pronotum of holotype, dorsal view B head of holotype, dorsal-frontal view C posterior edge of pronotum of holotype, left side, dorsal view, arrows indicating sublateral incisions D scutellar shield of holotype, dorsal view E metacoxal plate of paratype, ventral view.

Figure 23. Shape of supraantennal carina of Chinese Phorocardius species. Arrows indicating supraantennal carina forked near eye. A P. alterlineatus Ruan & Douglas, sp. nov. B P. flavistriolatus Ruan & Douglas, sp. nov. C P. florentini. D P. magnus. E P. manuleatus. F P. minutus Ruan & Douglas, sp. nov. G P. rufiposterus Ruan & Douglas, sp. nov. H P. unguicularis. I P. yunnanensis Ruan & Douglas, sp. nov. J P. zhiweii Ruan, Douglas & Qiu, sp. nov. K head, frontal-lateral view, arrows indicating forked supraantennal carina.

Figure 24. Lateral view of prosternal process and mesosternum of Chinese Phorocardius species. Upper green arrows indicating shape of posterior end of prosternal process; lower red arrows indicating projections (absent or present) on posterior edge of mesosternum (i. e., on anteroventral angle of mesosternal fossa according to Douglas 2003). A P. alterlineatus Ruan & Douglas, sp. nov. B P. flavistriolatus Ruan & Douglas, sp. nov. C P. florentini. D P. magnus. E P. manuleatus. F P. minutus Ruan & Douglas, sp. nov. G P. rufiposterus Ruan & Douglas, sp. nov. H P. unguicularis. I P. yunnanensis Ruan & Douglas, sp. nov. J P. zhiweii Ruan, Douglas & Qiu, sp. nov.

Figure 25. Ventral view of pro- and mesothorax of Chinese Phorocardius species. Showing shape of ventral surface of prosternal process (upper, yellow dashed line), mesepisternum (middle, green arrow and dashed line) and projections on posterior edge of mesosternum (lower, red arrow and solid line) middle, green arrows indicating anterior-mesal angle of mesepisternum. A P. alterlineatus Ruan & Douglas, sp. nov. B P. flavistriolatus Ruan & Douglas, sp. nov. C P. florentini. D P. magnus. E P. manuleatus. F P. minutus Ruan & Douglas, sp. nov. G P. rufiposterus Ruan & Douglas, sp. nov. H P. unguicularis. I P. zhiweii Ruan, Douglas & Qiu, sp. nov.