Scolytus jiulianshanensis Zhang, Li & Smith, 2021

Zhang, Ling, Li, You, Smith, Sarah M. & Wang, Jianguo, 2021, Scolytus jiulianshanensis, a new species of bark beetle (Coleoptera: Curculionidae: Scolytinae) from elm in China, Zootaxa 5057 (2), pp. 295-300 : 296-299

Scolytus jiulianshanensis Zhang, Li & Smith sp. nov.

http://zoobank.org/ urn:lsid:zoobank.org:act:EB8EBFE2-A128-4AA5-B864-8F34C5A4A911

Diagnosis (male). Scolytus jiulianshanensis is distinguished from all other Oriental Scolytus species by ventrite 2 nearly perpendicular to ventrite 1, basal margin of ventrite 2 slightly impressed, apical margin of ventrite 1 strongly thickened, forming a lip along the base of ventrite 2, apical margins of ventrite 3 and 4 each armed with a short and broad median tubercle and elytra subquadrate. The species can be distinguished from all other Scolytus by the lack of tubercles or spines on ventrite 2, apical margin of ventrite 1 strongly produced, forming carinate lip along basal margin of ventrite 2, apical margins of ventrite 3 and 4 each armed with a broad median tubercle, ventrite 5 without callosities or setal patches, elytral apex subquadrate and by the banded elytra.

Diagnosis (female). The species is distinguished from all other Oriental Scolytus by ventrite 2 perpendicular to ventrite 1, ventrite 2 lacking tubercles, spines or long median hairs, ventrite 5 without callosities, frons densely and deeply aciculate, without a median carina, elytral at least 1.2× as long as wide, pronotal base without a median triangular projection, ventrite 5 with a weak median longitudinal impression near apex and by the banded elytra.

Type material. Holotype (♂): China, Jiangxi Province, Ganzhou City, Longnan, Jiulianshan National Nature Reserve , N 24.55194°, E 114.435°, 491.7m, 1 July 2020; L. Zhang, S.-C. Lai & Y.-F. Cao leg. [IOZ(E)225773; National Zoological Museum of China, Institute of Zoology, Chinese Academy of Sciences, Beijing, China]

Allotype (♀): the same data as the holotype. [IOZ(E)225774; National Zoological Museum of China, Institute of Zoology, Chinese Academy of Sciences , Beijing, China]

Paratypes (8♂, 8♀): the same data as the holotype. (1♂, 1♀, Sun Yat-sen University, Guangdong, China; 1♂, 1♀, KIZ0121455-0121456 , Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming , China; 1♂, 1♀, same collection data except 16 October 2019, National Museum of Natural History , Washington D.C., USA; 1♂, 1♀, National Museum of Natural Science , Taichung, Taiwan; 1♂, 1♀, The Natural History Museum , London , United Kingdom; 1♂, 1♀, Research Institute of Forest Insect Diversity , Namyangju , South Korea; 1♂, 1♀, Zoological Institute , Russian Academy of Sciences , St. Petersburg, Russia; 1♂, 1♀, National Institute of Agro-Environmental Sciences , Tsukuba , Ibaraki, Japan.)

Description. ( Fig. 1 A-F). Male, total length 3.9–4.3 mm long (mean=4.04; n=10), 2.11–2.29 times as long as wide. Head, pronotum, elytra and abdominal venter black except the anterior margins of pronotum and posterior quarter of elytra banded with yellow-brown; legs and antennae yellow-brown.

Head. Epistoma weakly emarginate; epistomal process absent; median area above mandibles bearing dense patch of long, yellow, hair-like setae. Frons concave appearing flattened when viewed laterally; surface moderately, finely, longitudinally aciculate-punctate; aciculations converging at epistoma; punctures small, coarse; moderately covered by long, fine, yellow, erect, hair-like setae between apices of eyes, setae on lateral and dorsal margins longer, thicker, incurved. Antennal scape flattened, elongate; club irregularly ovoid, about twice as long as wide, setose with partial septum, two sharply arcuate sutures visible.

Pronotum about as long as wide; apical margin broadly rounded; sides distinctly arcuate, strongly constricted near apex, forming weak transverse impression near apical margin; surface smooth, shining, punctures on disc fine, shallow, moderately abundant, larger and more abundant laterally and on apical constriction; apical and anterolateral margins bearing sparse, erect, yellow, hair-like setae; base weakly bisinuate.

Scutellum triangular, deeply set in the scutellar impression.

Elytra 1.05–1.18 times as long as wide, 1.00–1.05 times as long as pronotum; sides sub-parallel in basal half, narrowing to subquadrate, smooth apex. Disc smooth, shining; striae moderately impressed, twice width of interstriae, punctures uniseriate, smaller than those of striae, punctures bearing short recumbent yellow setae, slightly longer than size of a puncture; all interstriae uniseriate except interstriae 2 biseriate in basal half. Declivity bearing sparse, long, erect yellow setae. Metepimeron greater than half-length of metanepisternum.

Venter. Apical margin of ventrite 1 strongly produced, forming carinate lip along basal margin of ventrite 2. Ventrite 2 nearly perpendicular to ventrite 1; surface smooth, shining, finely punctate; punctures small, coarse; surface basal margin of ventrite 2 appearing impressed; setae moderately abundant, erect, short. Apical margins of ventrite 3 armed with a triangular median tubercle, apical margins of ventrite 4 armed with a trapezoid median denticle. Ventrite 5 carinate ridge closer to apical margin of segment; length of ventrite 5 equal to combined lengths of ventrites 3 and 4; setal patch absent; median depression present.

Genitalia. ( Figs. 2 ). Aedeagus 0.8 mm long, stout, weakly sclerotized. Penis apodemes as long as penis body. Apical half of penis body bearing a triangle median lobe. Gastric spiculum about 0.6mm long, curving and without fork.

Female. ( Figs. 1 G-L). 3.5–4.2 mm long (mean=3.92; n=10); 2.10–2.33 times as long as wide. Similar to male except frons convex when viewed laterally, setae sparser, shorter, less than width of eye; apical margin of ventrite 1 weakly elevated above base of ventrite 2; ventrites 3 and 4 without median tubercles.

Host. Ulmus sp.

Distribution. The species is known only from the type locality in Jiulianshan National Nature Reserve in Jiangxi, China.

Etymology. The species name makes reference to the locality of the holotype, Jiulianshan Mountain.

Sequence Data. DNA was extracted from a specimen collected from same log (GenBank: COⅠ, Accession No. LC591987 ).

Biology. The species was first discovered in a dead elm tree in October 2019. The diameter at breast height of the elm tree was about 20cm. A small series consisting of a few larvae, pupae and adults were collected by bark dissection. To obtain more samples, we made a second trip to the same locality from June to July 2020. More adults were collected in a nearby dead elm tree. No observations were made of attack on a living tree. Galleries were observed ( Fig. 3 ) and consisted of a single longitudinal egg gallery (3.4–4.0 cm long) with a large nuptial chamber. The egg gallery strongly scores the sapwood. We observed 97 to 108 larval galleries in each egg gallery. Larval mines lightly score the sapwood and radiate perpendicular to the egg gallery. Larval galleries (4.6–5.2 cm long) later meander often at an oblique angle to the grain of wood, forming a fan shaped pattern that is typical for the genus ( Smith & Cognato, 2014).

Remarks. The male is considered to be a member of group II ( Michalski 1973) which consists of species that lack processes on ventrite 2 but have tubercles or spines on the posterior margins of ventrites 3 and 4 and the female is considered to be a member of group III which consists of species without spines or tubercles on the ventrites. There are no effective identification keys to species in China. The most complete by Yin et al. (1984) includes only eight of the 10 species reported from mainland China. In this key, this species would fail at couplet 20 because of the absence of tubercles on the apical margins of ventrites 3 and 4 of the female.

Figures

FIGURE 1 Scolytus jiulianshanensis. A) dorsal male habitus; B) lateral male habitus; C) male frons; D) male frons oblique; E) male venter; F) male venter oblique; G) dorsal female habitus; H) lateral female habitus; I) female frons; J) female frons oblique; K) female venter; L) female venter oblique.

FIGURE 2 Scolytus jiulianshanensis, male genitalia. A) Dorsal view; B) Lateral view; C) Gastric spiculum.

FIGURE 3 Galleries of Scolytus jiulianshanensis on Ulmus sp. found at the locality Jiulianshan Mountain (July 1, 2020)