Polyxenus hangzhoensis Ishii & Liang, 1990

Polyxenus hangzhoensis Ishii & Liang, 1990 View in CoL

Fig. 4 View Figure 4

Material examined.

China • 3 ♂ 4 ♀; Anhui, Chuzhou, Langya Mountain ; 32 ° 27 ' 67 " N, 118°30'01"E; 12 Mar. 2024; Y. D. Wang leg.; GenBank: PQ 142930; CBF CZCZS 1 .

Diagnosis.

Five ommatidia in each eye. Number of trichomes: posterior vertex, 47–48; collum, 54–55; collum’s lateral protuberance, 4–5; tergite II, 56–62; tergite III, 60–64. Four dorso-medial trichomes on the head, posterior vertex comprising 2 complete rows of trichomes with no medial gap. Antennal article VI with 2 thick basiconic sensilla, 1 setiform sensillum, and 6 thin basiconic sensilla. Antennal article VII with 2 thick basiconic sensilla, 1 setiform sensillum, 4 thin basiconic sensilla, and 1 conical sensillum.

Description.

Female. With 13 pairs of legs. Measurements: Body length 2.08 mm, caudal bundle 0.25 mm.

Head (Fig. 4 A View Figure 4 ): Eye consisting of 5 ommatidia. Trichomes on the posterior vertex are arranged in 2 rows with no medial gap: the anterior row consists of 26 trichomes, and the posterior row comprises 20 trichomes. Additionally, 4 trichomes are arranged transversely in a dorso-medial position (Fig. 4 A View Figure 4 ). The head features two types of trichomes (Fig. 4 J View Figure 4 ). Three trichobothria are positioned in an equilateral triangle, with the trichobothrium furthest from the ommatidia being slightly smaller than the other two (Fig. 4 A View Figure 4 ). The gnathochilarium possesses lateral palps that are 2.2 times the length of the medial palp. Lateral palps with 9 sensilla, medial palp with 17 sensilla (Fig. 4 F View Figure 4 ). The anterior margin of the labrum is granulated and armed with 5 + 5 lamellar teeth. The clypeo-labrum is equipped with 8 setae (Fig. 4 E View Figure 4 ).

Antennae: Long antennae with proportions of antennal articles as depicted in Fig. 4 G View Figure 4 . Antennal article VIII with 4 sensory cones, antennal article VI with 2 thick basiconic sensilla (anterior, a, and posterior, p); 1 setiform sensillum (s) between a and p, 6 thin basiconic sensilla behind p (Fig. 4 I View Figure 4 ). Antennal article VII with 2 thick basiconic sensilla (a and p), 1 setiform sensillum (s) between a and p, 4 thin basiconic sensilla in front of p, and 1 conical sensillum (c) behind a (Fig. 4 H View Figure 4 ).

Trunk: Tergal trichomes, including those on the collum, are arranged in a circular pattern. Collum with 54 trichomes, lateral protuberance of collum with 5 trichomes in a row (Fig. 4 B View Figure 4 ). Tergite II with 56 trichomes (Fig. 4 C View Figure 4 ). Tergite III with 60 trichomes (Fig. 4 D View Figure 4 ). Tergites II – X have the same pattern of trichome insertions.

Legs (Fig. 4 K View Figure 4 ): Coxa I with no seta, coxa II with 2 setae, coxae III – XIII with no seta, prefemur and femur with one seta (Fig. 4 M View Figure 4 ), trochanter, post-femur, and tarsus I with no seta. The spine on tarsus II is far shorter than the setae on the prefemur and femur (Fig. 4 L View Figure 4 ). There is a very small seta on the tibia (Fig. 4 N View Figure 4 ). The telotarsus consists of an anterior process with an enlarged base, nearly equaling the length of the claw. Both a lamella process and a small posterior process are present (Fig. 4 O View Figure 4 ).

Telson: The telson possesses 54 (27 + 27) dorso-medial trichomes in the caudal penicil (Fig. 4 Q View Figure 4 ), arranged in two bundles separated by a gap. The caudal bundles consist of two types of trichomes, with the hooked trichomes having an apical lobed hook typical of Polyxenus (Fig. 4 P View Figure 4 ).

Male. With 13 pairs of legs. Measurements: body length 1.9 mm, caudal bundle 0.22 mm. Posterior vertex with 48 trichomes, Collum with 55 trichomes, and tergites II and III with 62 and 64 trichomes. Coxa I with 1 seta, coxa II with 2 setae, coxae III – XIII with no seta. The caudal penicil comprises 48 (24 + 24) dorso-medial trichomes.

Distribution.

China (Zhejiang, Anhui).

Remarks.

This species closely resembles Polyxenus shinoharai Ishii, 1983 but differs in the number of trichomes present: the posterior vertex has 47 or 48 (40 or 41 in P. shinoharai ), the collum with 54 or 55 (41 or 42), the lateral protuberance of the collum bears 4 or 5 (3), tergite II exhibits 56–62 (41 or 43), and tergite III displays 60–64 (42 or 46), antennal article VI with 6 thin basiconic sensilla (7 in P. shinoharai ).