Xizangia qiuae Huang & Chen, 2022

Huang, Hao & Chen, Chang-Chin, 2022, Rediscovery of the myrmecophilous Lucanid genus Xizangia Zhang, 1988 from southwest China (Coleoptera: Scarabaeoidea: Lucanidae), Zootaxa 5116 (4), pp. 517-549 : 519-538

Xizangia qiuae Huang & Chen , new species

( Figs. 1–8 , 15–19 , 21–26 , 28–31 , 33–58 )

Type locality. China, Yunnan Province, Xishuangbanna Prefecture, Mengla County, Yiwu .

Type material. Holotype ( Figs. 15 , 22 ): CHINA: Yunnan Prov.: ♂, Xishuangbanna prefecture, Mengla County, Yiwu , 1600m, third instar larva collected in an ant nest on 1.II.2017 by Jian-Yue Qiu and Hao Xu and emerged in the laboratory on 30.IV. –28.V. 2017 (Mianyang Normal University, Mianyang, Sichuan) . Paratypes (9 ♂♂ & 14 ♀♀ in total): CHINA: Yunnan Prov.: 6 ♂♂ & 10 ♀♀, same data as for the holotype ; 3 ♂♂ & 3 ♀♀, same data as for the holotype, collected as adults (3 ♀♀ in Mianyang Normal University , 1 ♂ & 2 ♀♀ in coll. S. Kakizoe, 4 ♂♂ & 4 ♀♀ in coll. H. Huang, 4 ♂♂ & 4 ♀♀ in coll. C.-C. Chen). 1 ♀, Dehong prefecture, Longchuan, Mangdong, 1770m, 2.VI.2016, legit Yu-Tang Wang, using a flight intercept trap (in coll. C.-C. Chen).

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Holotype description.

Measurement. Body length, measured from the anterior margin of head to the posterior margin of elytra: 6.68 mm; body thickness: 1.35 mm; head width: 2.53 mm; pronotum width: 2.85 mm; elytra width: 2.90 mm; body thickness/body length: 0.20; elytra width/body length: 0.43.

Body rectangular, strongly compressed dorso-ventrally; color dark reddish brown. Head: Transverse, surface punctate and glabrous; clypeus oblong, defined posteriorly by a transversal depression and laterally by a pair of longitudinal depressions; anterior margin broadly rounded, not emarginated, at most with a pair of weak indentations at lateral corners of clypeus, and with mandibles invisible from above; ocular canthus very large, dilated. Labrum small, triangular in anterior view and trapezoidal in ventral view, completely fused with clypeus (without suture), raised from the ventral surface of clypeus, extending downwards to fix the inner sides of mandibles. Mandibles small and slender, sharply pointed at apex; left mandible with a ventral tooth, right mandible with a medial tooth raised from dorsal surface. Maxilla: galea very small and brush-like at apex, lacinia small and free at apex, without a hook, maxillary palpus with 4 palpomeres, with terminal palpomere 3 times as long as wide. Labium consisting of a ligula and separated palpus on anterior portion of dorsal surface of mentum; ligula stick-like, longer than wide, rounded at apex and not bilobed, extending ventrally between bases of palpal insertions; palpal insertions separated by the ventral extension of ligula which is as wide as basal palpifer; labial palpus with 3 palpomeres (not counting basal palpifer). Mentum in ventral view more or less trapezoidal, with both anterior and posterior margins concave; mentum in anterior view half-rounded with outer anterior margin convex; surface sparsely punctate, glabrous. Submentum expanded at anterior part, sparsely setose, not clearly separated from impunctate, glabrous gula. Eye twice as long as wide in dorsal view. Antenna with ten antennomeres; both antennomeres 1 and 2 geniculate; antennomeres 3–7 being gradually widened distally and without hairy sensorial areas, antennomeres 6 and 7 being more pointed at inner apex, antennomeres 5–7 with a pair of setae at inner apex; club distinctly formed by the last 3 antennomeres (8–10), antennomere 8 with a small hairy sensorial area at inner apex, antennomere 9 being mostly hairy except for distal marginal area, antennomere 10 being completely hairy on external surfaces (glabrous only at proximal side); 2 small, round holes present longitudinally (transversely in Penichrolucanus species) in the midline on top of antennomere 10. Pronotum: Transverse, slightly wider in posterior half than in anterior half, base convex, anterior margin almost straight; surface punctate and glabrous, each side with superficial longitudinal, curved wrinkles and with a small laterodiscal depression. Intercoxal process of prosternum narrow, convex dorsally, expanding posteriorly, with all margins not ridged, not high above mesosternum, and associated with a pair of additional tubercles at posterior corners. Mesocoxae separated by flat, clearly ridged anterior projection of metasternum. Metacoxae remote from mesocoxae, not intruded by posterior part of metasternum. Scutellum: Ogival. Elytra: Longer than head and prothorax combined, parallel-sided, with 6 thin striae, interstriae superficially punctate; intervals between striae very finely punctate.Abdomen with five visible abdominal ventrites; first projected anteriorly, forming an intercoxal process of hind legs, somewhat triangular in shape; all ventrites finely punctate and glabrous, with lateral wrinkles as in metasternum. Legs: Short; all tibiae straight, protibia with three continuous triangular teeth in addition to the well-developed apical fork, meso—and metatibiae with two spines on external margins; protarsus with tarsomeres 1–4 short, subequal in length, fused together, tarsomere 5 longer than others combined; meso—and metatarsi with 3 segments, and with last tarsomere more depressed than in protarsus; a pair of claws hidden in terminal cavity of last tarsomere, arolium absent.

Hindwing (terminology follows Kukalová-Peck & Lawrence 1993) 7.4 mm long; vein RP absent, vein MP 3 absent, vein RA 4 remote from costa of hindwing, vein RP 1 with basal part present but with apical part absent, vein AA 1+2 reaching vein CuA to form a close cell.

Last tergite without colourless stripe. Last sternite without colourless area, and with posterior margin in a smooth curve at middle. Paired pleurites of 9th abdominal segment large and close, contracted at medial part. Ventral plate of 9th abdominal segment expanded at terminal end, strongly sclerotized, without lateral processes, and with no longitudinal carinae. Male genitalia with a pair of struts articulating near the proximal end of median lobe and enclosed by basal piece; basal piece with no dorsal plates, and with ventral surface largely colourless and membranous at caudal part, forming a large triangular excavation on the pigmented part; median lobe with a dorsal crossbar at base and with lateral bridge between base of median lobe and dorsal crossbar; dorsal crossbar of median lobe with dorsal margin connected by membrane to an extra plate (not found in other Lucaninae tribes) extending proximally into basal piece; median lobe simple, oblong, depressed dorso-ventrally, even in width, extending proximally and rounded caudally in ventral view, with ventral surface evenly pigmented, and with dorsal surface membranous and not expansible; permanently everted internal sac depressed and nearly even in width throughout, neither contracted nor expanded at apex, and clothed with microsetae.

Male paratypes

Body length: 6.60–7.30 mm.

Variation.Anterior margin of head a little variable in the detailed shape. Meso—and metatibiae sometimes with additional one or two denticles.

Female paratypes ( Figs. 1–2 , 16–19 , 23–26 )

Body length: 6.70–7.50 mm.

Sexual dimorphism only found in length of ventral tooth of left mandible and length of last abdominal ventrite. Ventral tooth of left mandible longer than in male. Last ventrite more than 1.5 times longer than penultimate ventrite (less than 1.5 times as long as penultimate ventrite in male).

Hindwing as in male, with no difference in size, shape, and venation.

Female genitalia ( Figs. 41–42 ). Hemisternites well sclerotized and setose near apex, with styli sclerotized, non-setose, hawk-beak-like and pointed outwards; spermatheca tube-like and rounded at apex, pigmented at apical half but colourless at basal half; spermathecal duct not defined as the membranous tube connected to spermatheca expansible and better explained as bursa copulatrix; spermathecal gland and its duct originated from spermatheca near base, rather short.

The unique female specimen from Mangdong, SW. Yunnan, another locality, does not show any reliable difference from the specimens from Xishuangbanna, SC. Yunnan, the type locality.

Diagnosis. This new species is distinguishable from Xizangia cryptonychus ( Figs. 9–14 , 20 , 27 ) from Motuo, SE Tibet in female by having a shorter ventral tooth of left mandible ( Figs. 29–32 ), a shorter inner spur at apex of protibia ( Fig. 33 ), the shorter last tarsomeres in all legs ( Fig. 33 ), the fewer external spines in all tibiae, and the less convex intervals between striae on the elytra. It can be supposed that these differences should also be present in male as no sexual dimorphism of these characters is found in the known species of Penichrolucanini .

Only the two female type specimens are known for Xizangia cryptonychus , both deposited in Institute of Zoology, Chinese Academy of Science; the holotype remains untraceable (M.-Y. Lin & M. Bai, personal communications, 2018). The last abdominal segments of the only available female paratype are missing, most probably dissected by its author during the first research, therefore a comparison of genital structures between the two species is not possible at present.

Etymology. The new species is named in honor of Dr. Qiu Jian-Yue, one of the collectors of the new species.

Larval morphology ( Figs. 44–57 )

A detailed description of the third instar larva of Xizangia qiuae , new species is given below.

Antenna ( Figs. 48 , 53–54 ): Antenna 3-segmented (excluding antennifer). Basal antennomere subdivided, with an unpigmented ring near base, indicating it is formed by two segments, completely fused; it bearing very few sensory spots and small setae. Penultimate antennomere (antennomere 2) as long as and markedly wider than basal antennomere, with more sensory spots and small setae than basal antennomere, and with no large sensorium below last antennomere (antennomere 3). Last antennomere very small, with very few setae and sensory spots, and with no apical appendage. Epipharynx ( Fig. 56 ): Phoba divided into an anterior section (namely protophoba) and lateral sections (namely chaetoparia). Protophoba distinct and consisting of 11 short, blunt and densely arranged setae, and with about 3 sensory spots. Haptomerum hardly separated from protophoba, consisting of 2 sensory spots, without setae. Setae in chaetoparia very few and much sparser than in protophoba. Haptolachus consisting of 2 nesia, the median one being more elongate and bearing very small granules; all nesia without setae. Epitorma well sclerotized but very small and short. Pternotorma well developed and very long. Mandibles ( Fig. 55 ): Left mandible with 3 apical teeth at tip, a complicated mola at basal half, a ventral process at base and a minute inner tubercle along the inner edge between apical teeth and mola; apical teeth all blunt, with dorsal one shorter and ventral one longer; inner tubercle minute, not forming clear tooth; mola triangular in both dorsal and ventral views, somewhat square in inner lateral view, and with a deep furrow between dorsal and ventral surfaces. Right mandible with 2 apical teeth at tip, 2 simple molae at base and an inner tubercle between apical teeth and molae; apical teeth with dorsal one shorter and blunter than ventral one; inner tubercle minute; both basal and distal molae restricted to dorsal side, rather short; ventral process fully developed as in left mandible. Outer edge of both mandibles coarse and dentate, with very few minute setae. Mouthparts ( Fig. 57 ): Stipes without stridulatory teeth. Galea and lacinia separate and fixed to stipes. Galea with membranous subdivision. Lacinia single-pointed at apex. Maxillary palpus with 3 palpomeres excluding palpifer and with palpifer present. Ligula absent. Labial palpus with 2 palpomeres, rather straight and glabrous, without palpifer. Hypopharynx not markedly asymmetrical, with right dorsally pointed sclerotized projection visible in oblique view.

Prothorax ( Fig. 44 ): Pronotum without an anteriorly projecting lobe or an extensive pronotal plate. Precoxale and episternum hardly sclerotized. Mesocoxal stridulatory organ (pars stridens, Fig. 50 ): Pars stridens on posterior surface of mesocoxa consisting of a main carina and a field of minute, rounded granules, all about equal in size, without well developed granules outside of the main row. Metatrochanteral stridulatory organ (plectrum, Figs. 51–52 ): Plectrum on anterior surface of metatrochanter consisting of a single row of continuous granules which might be interrupted by a empty field; granules a little rounded or oblong, smaller in terminal part than in basal part. Tarsungulus: Tarsungulus of prothoracic leg ( Fig. 49 ) 2 times longer and more gradually attenuated at apex than that of mesothoracic ( Fig. 50 ) and metathoracic legs ( Fig. 51 ), flanked by 2 shorter setae arising from the same position on each side. Tarsungulus of mesothoracic and metathoracic legs strongly and abruptly attenuated at apex, flanked by 2 longer setae arising from the same position on each side.

Vestiture of thoracic and abdominal tergites ( Figs. 44–45 ): All tergites sparsely clad with small setae; spinules absent from thoracic tergites and abdominal tergites 1 and 7–10, very few on abdominal tergites 2–6. Vestiture of abdominal sternite 10 ( Fig. 46 ). Raster well developed as two lateral groups of posteromesally directed spinules. Anal sclerite. Dorsal lobe obsolete. Lateral lobes with very few setae.

Notes. In Emden (1935, 1951) and Lawrence (1981) works the number of inner teeth on the left mandible was used as a major character in larval classification, and a major split is based on the presence of at least one tooth along the inner edge of the left mandible between the two or three apical teeth and the mola, with the larvae possessing such inner teeth belonging to the subfamily Lucaninae (sensu Holloway 1968) whilst the group lacking inner teeth includes Aesalus Fabricius, 1801 , Sinodendron Hellwig, 1792 , Ceruchus MacLeay, 1819 , Nicagus LeConte, 1861 , Syndesus MacLeay, 1819 , Ceratognathus Westwood, 1838 , and the subfamily Lampriminae . However, Xizangia qiuae , new species shows only minute inner tubercle between apical teeth and mola, without distinct excision in front of the tubercle, which cannot be distinguished from that of Aesalus satoi Araya & Yoshitomi, 2003 ( Huang et al. 2009). Therefore, the presence or absence of inner teeth should not be used as a major character in classification of larval Lucanidae .

Xizangia qiuae , new species larva possesses the following distinct differences from Figulus foveicollis (Boisduval, 1835) (larva described in Emden 1951) and F. lilliputanus Westwood, 1855 (larva described in Lawrence 1981): antenna 3-segmented with basal antennomere subdivided by an unpigmented ring near base, not distinctly 4-segmented; left mandible without large inner tooth; haptomerum with very few sensory spots but without setae; chaetoparia with markedly sparser setae; haptolachus with left nesia present but with no right nesia; epitorma pointed, not obsolete; sternite 10 with distinct raster which is interrupted on median line by a smooth longitudinal strip; plectrum being a single row of the conjoined tubercles; par stridens with most part of main row of tubercles conjoined (as in Cardanus ), not separated, and without granules outside of main row; the two setae of the claw inserted side by side (as in Nigidius ), not behind each other.

Xizangia qiuae , new species larva differs from the one of Nigidius perforatus Harold, 1878 (larva described in Emden 1935, 1951, but with characters of antenna, epipharynx and mouthparts not clarified) by the following points: left mandible without large inner tooth; tergites 7–10 (as in Figulus and Cardanus ) without spinules; sternite 10 with raster interrupted on median line by a smooth longitudinal strip; plectrum being a single row of the conjoined tubercles; par stridens with most part of main row of tubercles conjoined, not separated, and without granules outside of main row; claw with a subapical sinuation (as in Figulus and Cardanus ), not evenly tapering.

Xizangia qiuae , new species larva is different from the one of Cardanus sp. (larva described in Emden, 1935, 1951, but with characters of antenna, epipharynx and mouthparts not clarified) by the following points: left mandible without large inner tooth; sternite 10 with distinct raster which is interrupted on median line by a smooth longitudinal strip; tibiotarsus about twice as long as wide (as in Figulus and Nigidius ), not extremely short; plectrum being a single row of the conjoined tubercles; par stridens without granules outside of main row; the two setae of the claw inserted side by side (as in Nigidius ), not behind each other.

As a conclusion, Xizangia differs from Figulus , Cardanus and Nigidius by having left mandible without large inner tooth, sternite 10 with raster interrupted on median line by a smooth longitudinal strip, plectrum being a single row of the conjoined tubercles, and par stridens without granules outside of main row. This may indicate that Penichrolucanini is separable from Figulini in systematics also by larval characters, but more species of both tribes need to be examined in future.

Pupa ( Fig. 58 ) as figured.

Biological notes ( Figs. 59–67 ). All adults and third instar larvae ( Figs. 64, 66 ) of Xizangia qiuae , new species were found in a large fallen wood ( Fig. 62 ), immediately below the bottom of an ant nest. The fallen wood was found in a tea field ( Fig. 60 ) in a tropical montane evergreen broad-leaved forest area ( Fig. 59 ) at 1600m. The ants were identified as Dolichoderus sp. ( Fig. 67 ) ( Hymenoptera : Formicidae : Dolichoderinae ), being close to Dolichoderus incisus Xu, 1995 (Type locality: Lincang, Yunnan). The nest of the Dolichoderus ant was located at the center of the log, consisting of layers of shells; most parts of the log were not decayed. Adults ( Fig. 65 ) and larvae (mostly in cocoon, see Fig. 66 ) of Xizangia qiuae , new species were gathered in the decayed part of the wood just below the ant nest, not inside the ant nest. The ants ( Figs. 61, 63 ) did not visit the part where Xizangia qiuae , new species lived but would attack Xizangia qiuae , new species if the wall between the ant nest and the Xizangia nest was broken. Also Aegus taurus Boileau, 1899 (Lucanidae) was found living together with Xizangia qiuae , new species in the decayed part of the wood.

According to Geiselhardt et al. (2007), the following Paussinae taxa have been recorded as the guests of the Dolichoderini ants ( Dolichoderinae ): Homopterus steinbachi Kolbe, 1920 , Arthropterus sp. , Paussus thomsonii Reiche, 1860 and Paussus cochlearius Westwood, 1838 ; only Homopterus steinbachi Kolbe 1920 in Neotropical Region is recorded as the guest of the Dolichoderus ants.

Figures

FIGURE 20. Xizangia cryptonychus Zhang, 1988, habitus in dorsal view (female paratype).

FIGURE 21. Xizangia qiuae Huang & Chen, new species, legs (F2).

FIGURES 22–26. Xizangia qiuae Huang & Chen, new species, habitus in ventral view (M1, F1, F2, F3 and F4).

FIGURE 27. Xizangia cryptonychus Zhang, 1988, habitus in ventral view (female paratype).

FIGURE 28. Xizangia qiuae Huang & Chen, new species, metatarsi in ventral view (F1).

FIGURES 29–31. Xizangia qiuae Huang & Chen, new species, mandibles in ventral view (F3, F2 and F1)

FIGURE 33. Diagnostic characters of Xizangia species: legs.

FIGURE 34. Xizangia qiuae Huang & Chen, new species, mandibles in dorsal, inner lateral and ventral views: left half — male mandibles; right half — female mandibles.

FIGURES 35–39. Xizangia qiuae Huang & Chen, new species, characters. 35, hindwing; 36, female antenna in various views; 37, maxilla and labium; 38, clypeus, labrum and mentum in anterior view; 39, clypeus, labrum and mentum in ventral view.

FIGURE 40. Xizangia qiuae Huang & Chen, new species, tarsi and claws.

FIGURES 41–42. Xizangia qiuae Huang & Chen, new species, female genitalia.

FIGURE 43. Xizangia qiuae Huang & Chen, new species, male genitalia (M1—holotype).

FIGURES 44–48. Xizangia qiuae Huang & Chen, new species, larva and its characters. 44, larva in lateral view; 45, larva in dorsal view; 46, tenth abdominal segment in ventral view to show raster; 47, head in frontal view; 48, left antenna in lateral view.

FIGURES 49–52. Xizangia qiuae Huang & Chen, new species, larva legs. 49, foreleg in lateral view; 50, midleg in lateral view, with pars stridens enlarged; 51, right hindleg in lateral view, with plectrum enlarged; 52, plectrum of left hindleg.

FIGURES 53–57. Xizangia qiuae Huang & Chen, new species, larva characters. 53, left antenna with apical antennomere enlarged; 54, right antenna with apical antennomere enlarged; 55, mandibles in dorsal, inner lateral and ventral views; 56, epipharynx in ventral view; 57, mouthpart.

FIGURE 58. Xizangia qiuae Huang & Chen, new species, pupa in dorsal, lateral and ventral views.

FIGURE 67. Habitus and characters of Dolichoderus species worker living with Xizangia qiuae Huang & Chen, new species.

FIGURES 1–2. Xizangia qiuae Huang & Chen, new species. 1, habitus in dorsal view; 2, habitus in ventral view (F4—female paratype from Mangdong).

FIGURES 3–8. Xizangia qiuae Huang & Chen, new species, habitus and details (F4). 3, entire body in lateral view; 4, top of last antennomere; 5, part of head in ventral view; 6, left antenna in ventral view; 7, intercoxal process of prosternum; 8, part of head in dorsal view.

FIGURES 15–19. Xizangia qiuae Huang & Chen, new species, habitus in dorsal view (M1—male holotype, F1—female paratype, F2—female paratype, F3—female paratype and F4 —female paratype).

FIGURES 9–14. Xizangia cryptonychus Zhang, 1988, habitus and details (female paratype). 9, entire body in lateral view; 10, top of last antennomere; 11, part of head in ventral view; 12, antenna; 13, intercoxal process of prosternum; 14, part of head in dorsal view.

FIGURE 32. Xizangia cryptonychus Zhang, 1988, mandibles in ventral view (female paratype).

FIGURES 59–66. Xizangia qiuae Huang & Chen, new species, biotope and field observations (photo by H. Xu). 59, biotope; 60 and 62, fallen wood in which the ant nest was found; 61 and 63, broken ant nest and ant workers; 64 and 66, larva of Xizangia qiuae in cocoon; 65, living adult of Xizangia qiuae found below ant nest.