Dichodontocis guangzhouensis, Li & Xu, 2024

Li, Nan & Xu, Ji-Shan, 2024, The first record of the genus Dichodontocis Kawanabe, 1994 (Coleoptera, Ciidae) from China, with the description of a new species and its larva, ZooKeys 1218, pp. 145-154 : 145-154

publication ID	https://doi.org/ 10.3897/zookeys.1218.130088
publication LSID	lsid:zoobank.org:pub:967D98C9-BE39-4DC2-8288-458993FEEDF0
DOI	https://doi.org/10.5281/zenodo.14193031
persistent identifier	https://treatment.plazi.org/id/B4A69A0A-6660-5CF5-A205-80DD5EA25E32
treatment provided by	ZooKeys by Pensoft
scientific name	Dichodontocis guangzhouensis
status	sp. nov.

Treatment

Dichodontocis guangzhouensis sp. nov.

Figs 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3

Type material.

Holotype: China • male, “ China: Guangdong, Guangzhou (广州), Huangpu District (黄埔区), Tianlu Lake Forest Park (天鹿湖森林公园), 23°12'N, 113°25'E, 303 m, 05.XI.2023, leg. Da-Rui Mo ” GoogleMaps . Paratypes: China • 3 males, 6 females, same data as the holotype GoogleMaps .

Diagnosis.

This new species is similar to D. uncinatus from southern Japan. From the illustration of the holotype ( Kawanabe 1994), the elytral setae appear to be more clearly seriate and ordered in that species than in D. guangzhouensis sp. nov., both anal veins of hind wings are absent, but in D. guangzhouensis sp. nov. the hind wings have apical color spots (Figs 1 D View Figure 1 , 3 D View Figure 3 ) and the impression of the anterior margin of pronotum of D. guangzhouensis appears broadly and deeply impressed and extends posteriorly, distinctly beyond the bases of the horn, while in D. uncinatus , from the illustration of the holotype ( Kawanabe 1994), the impression of the anterior margin of pronotum is only between the bases of the horn and much weaker than in D. guangzhouensis sp. nov.. The terminalia are somewhat different. In D. uncinatus , the eighth abdominal sternite has the posterior margin slightly emarginate at the middle, and the anterior margin strongly emarginate. In the new species, however, the eighth abdominal sternite with the posterior margin is broadly emarginate in the middle, anterior margin is not emarginate (Fig. 2 I View Figure 2 ) in the middle. The tegmen is broad at the base and gradually narrower near the end in D. uncinatus . In the new species, the tegmen is broad at the base, from base 1 / 5–4 / 5, the sides are nearly parallel, and gradually narrower near the end, slightly curving.

The new species is also similar to D. queenslandicus from northern Queensland. The size and dimensions of the two species are similar. But there are some differences between the two species. Head relatively and largely exposed, partially visible from above in D. queenslandicus . Head almost entirely exposed, visible from above in the new species. The impression of the anterior margin of the pronotum of D. guangzhouensis sp. nov. appears broadly and deeply impressed and extends posteriorly, distinctly beyond the bases of the horn, while in D. queenslandicus , from the illustration of the holotype ( Lawrence 2016), the impression of the anterior margin of pronotum is slightly weaker and more in front than in D. guangzhouensis sp. nov. The tegmen of D. queenslandicus is 4 times as long as wide, and the pens is 4 times as long as wide. The tegmen of the new species is 6.4 times as long as wide, pens 8.0 times as long as wide. The sternite VIII of the D. queenslandicus is the posterior margin slightly emarginate in the middle, the eighth abdominal sternite of the new species with the posterior margin is broadly emarginate in the middle, anterior margin is not emarginate (Fig. 2 I View Figure 2 ) in the middle.

Description of the adult.

With the characters of the genus. Male. Fully pigmented adult. Measurements in mm: TL 1.511, PL 0.678, PW 0.695, EL 0.833, EW 0.717, GD 0.636. Ratios: PL / PW 0.98, EL / EW 1.16, EL / PL 1.23, GD / EW 0.89, TL / EW 2.11.

Body (Fig. 1 C View Figure 1 ) elongate, convex, reddish brown to dark brown; dorsal setae, tarsi, antennae (except club), maxillary palpus and labial palpus are pale yellow; dorsal vestiture dual, consisting of long and short erect setae.

Head wider slightly than long, partially visible from above, with sparse punctures and dual setae, frontoclypeal strongly elevated forming a pair of broad-based, reflexed at each side subtriangular plates, behind eyes. Compound eyes are finely facetted and suboval, each bearing approximately 70 ommatidia; GW 0.17 mm. Antennae (Fig. 2 A View Figure 2 ) bearing 10 antennomeres with the following lengths (in mm): 0.07, 0.05, 0.04, 0.03, 0.02, 0.02, 0.02, 0.05, 0.05, 0.08. Mandibles are asymmetrical (misaligned), with well-developed, transversely ridged molae.

Pronotum (Fig. 1 C View Figure 1 ) is as long as broad and parallel-sided, which is slightly raised in the middle with shallow and fine punctures bearing short and long dual setae, erect. Punctures are separated by a distance equal to one to two diameters. Lateral margins (Fig. 1 B, C View Figure 1 ) are narrow, and not visible for their entire lengths from above. Anterior edge produced forward and upturned into two small lateral projections. The anterior edge deeply and broadly emarginate in the middle just like a horseshoe, and the impression of the anterior margin of the pronotum extends posteriorly, distinctly beyond the bases of the horn. Anterior angles (Fig. 1 B View Figure 1 ) obtuse. Posterior margin (Fig. 1 B View Figure 1 ) feebly bisinuous posterior angles rounded.

Scutellar shield developed, with a few punctures and setae; subtriangular, BW 0.13 mm.

Elytra (Fig. 1 C View Figure 1 ) 1.2 times as long as broad, 1.3 times as long as pronotum; punctures rough; setae dual short and long, inclined and suberect; sides subparallel in basal 2 / 3, then gradually convergent apical.

Hind wings (Fig. 1 D View Figure 1 ) are fully developed, nearly pellucid. The venation type is folding patterns. Strongly reduced venation patterns of the clavus, anal vein absent. A medial field with one vein and a small fleck, a medial embayment, a small support sclerite near the wing apex; with a distinct cubitoanal strut and radiomedial loop. The hind wings are 3.3 times as long as broad, the widest part is in the middle, shrinking to the sides.

Protibia (Fig. 2 B, C View Figure 2 ) expanded to the apex, outer apical angle with 2 acute teeth and dentate along the outer edge which are shorter near the base and gradually becoming longer towards the apex. Meso-and metatibia (Fig. 2 G, H, J, K View Figure 2 ) expanded forming a rounded lobe lined with socketed spines.

Prosternum (Fig. 1 A View Figure 1 ) is weakly biconcave and subcarinate; the prosternal process is flaked and slender somewhat slightly broadened near the apex, slightly higher than the procoxae (best seen in lateral view).

Metaventrite (Fig. 1 A View Figure 1 ) is convex but slightly emarginate in the middle, with sparse punctuation and bristles; discrimen nearly one-fourth length of ventrite. Abdominal ventrites (Fig. 1 A View Figure 1 ) with fine setae and shallow puncture, the surface between them microreticulate; the first abdominal ventrite is 2.2 times as long as 2 nd, the ventrites bearing a small, circular, not obvious and marginally pubescent fovea. The length of the ventrites (in mm) is as follows: 0.202, 0.093, 0.077, 0.072, 0.078.

Aedeagus 4.9 times as long as ventrite 5. Tegmen (Fig. 2 D, E View Figure 2 ) is slender 6.4 times as long as the widest, widest at the base and gradually narrower near the apex with the basal end subacute like a hook; narrowed gradually from base to apex; apex slightly bent. Penis (Fig. 2 E View Figure 2 ) is shorter and narrower than the tegmen, 8.0 times as long as the widest, with a subacute apex and moderately long, sides parallel from basal to four fifth, then just like the rhombus near the end. The basal piece is weakly sclerotized, much longer than a broad, like a narrow horseshoe. The sternite VIII (Fig. 2 I View Figure 2 ) with the posterior margin broadly emarginate in the middle, with several short hairs on each side, anterior margin not emarginate. The tergite VIII (Fig. 2 I View Figure 2 ) with the posterior margin not emarginate in the middle, anterior margin strongly emarginate.

Female (Fig. 3 View Figure 3 ). Similar to male, except for the following points: frontoclypeal without strongly subtriangular plates; pronotum with anterior edge broadly rounded, without projections; first abdominal ventrites without a sex patch. The eighth abdominal sternite of females is different from males. The posterior margin is not emarginate in the middle which is flat and the anterior margin is strongly emarginate in the female. Female genitalia (Fig. 3 E, F View Figure 3 ) is as long as wide, widest at the middle; paraprocts (Fig. 3 E View Figure 3 ) is 0.85 times as long as gonocoxites.

Measurements. Males (n = 3, including the holotype; mm): TL 1.48–1.51 (1.50 ± 0.02); PL 0.66–0.68 (0.67 ± 0.01); PW 0.70–0.71 (0.70 ± 0.01); EL 0.83–0.84 (0.87 ± 0.01); EW 0.70–0.72 (0.71 ± 0.01); GD 0.63–0.64 (0.64 ± 0.01).

Females (n = 6; mm): TL 1.18–1.48 (1.33 ± 0.10); PL 0.46–0.60 (0.55 ± 0.06); PW 0.51–0.65 (0.59 ± 0.06); EL 0.72–0.90 (0.78 ± 0.07); EW 0.58–0.70 (0.65 ± 0.44); GD 0.56–0.74 (0.67 ± 0.08).

Distribution.

Tianlu Lake Forest Park, Guangzhou, Guangdong, China.

Host fungi.

Unidentified Polyporaceae (Fig. 6 View Figure 6 ).

Etymology.

The specific name guangzhouensis is taken from the type locality, Guangzhou.

Description of larva.

Figs 4 View Figure 4 , 5 View Figure 5 . Larva material. “ China: Guangdong, Guangzhou (广州), Huangpu District (黄埔区), Tianlu Lake Forest Park (天鹿湖森林公园), 23 ° 12 ' N, 113 ° 25 ' E, 303 m, 05. XI. 2023, leg. Da-Rui Mo ”. We are sure that the polypore basidiomes contain only one species of insect, after rearing the larvae in the laboratory, it was found that they developed into adults of the new species successfully; however, their stadiums were not accurately recorded.

This description is based on a later instar larva (Fig. 4 View Figure 4 ); 1.69 mm long, 0.35 mm broad, head-capsule of 0.31 mm wide. The body is opal and translucent except for the head, pretarsus (claw) and pygidium, which are light yellow to dark brown.

Body elongate, more or less parallel-sided, subcylindrical, slightly curved ventrally. Surfaces are relatively smooth except for the mouth frame and tips of urogomphi, rarely with light tergal plates on most segments, smooth with vestiture of scattered long and short setae.

Head subspherical, protracted and moderately to strongly declined (hypognathous); posterior edge not emarginate. The epicranial stem (Fig. 5 D View Figure 5 ) is long with median endocarina (Fig. 5 D View Figure 5 ) beneath it; frontal arms (Fig. 5 D View Figure 5 ) are Y-shaped, with five stemmata on each side.

Antennal (Fig. 5 H View Figure 5 ) insertion is a well-developed and concealed maxillary articulatory membrane. Antennae are very short with 2 segments which have a sensorium on the first segment and a long seta on the apical antennomere. The 1 st segment is wider and shorter than the 2 nd.

Mandibles (Fig. 5 B, C View Figure 5 ) are large, robust, asymmetrical, and bidentate (one is large and the other is small), with a simple and transversely cutting edge.

Ventral mouthparts (Fig. 5 A View Figure 5 ) retracted; stipes longer than wide; maxillary articulating area (Fig. 5 A View Figure 5 ) reduced; galea (Fig. 5 A, E, F View Figure 5 ) rounded; lacinia (Fig. 5 E View Figure 5 ) represented by a short, truncate, subapical, lobe on the dorsal surface (ventral side not visible); palp (Fig. 5 A View Figure 5 ) 3 - segmented.

Labium (Fig. 5 A View Figure 5 ) with submentum, mentum, bearing short ligula and 2 - segmented palps. Hypopharyngeal sclerome absent.

Hypostomal rods absent; ventral epicranial ridges present.

Gula (Fig. 5 A View Figure 5 ) is wider than long, fused to the submentum.

Thoracic terga without transverse carinae or rows of asperities. Prothorax (Fig. 4 View Figure 4 ) is only slightly larger than meso- or metathorax.

Prosternum without special armature. Thoracic legs (Fig. 5 J View Figure 5 ) are short and broad, subequal; 5 - segmented with pretarsus (claw), bearing a few setae; coxae relatively close together.

The length of the abdomen is more than twice as long as thorax; terga and sterna without patches.

Terga IX (Fig. 5 K, L View Figure 5 ) is slightly transverse and longer and has variously modified, with concave and heavily sclerotized disc and with a pair of upturned urogomphi whose color is deepened from brown to black. There are 4–6 dark-colored, small protrusions between the urogomphi. There are also five protrusions on each side of the terga. Segment X (Fig. 5 K View Figure 5 ) is transverse, posteroventrally oriented. It is only about ½ as long as terga IX; anal opening transverse. Spiracles are annular.

Measurements. Later instar larva (n = 5, mm): TL 1.33–1.75 (1.61 ± 0.17); Wide 0.31–0.35 (0.34 ± 0.02).

Comments.

Currently, there are only three species of Dichodontocis known in the world. The type species, D. uncinatus is distributed in southwestern Japan (Yakushima island). Dichodontocis queenslandicus occurs in a rainforest in Australia (Queensland). The new species is known from Guangzhou (Tianlu Lake Forest Park), China. As they are distributed in hot, rainy environments, more Dichodontocis species may eventually be found in tropical areas of Asia and Australia.