Sweltsa sp.

Rehman, Abdur, Huo, Qing-Bo & Du, Yu-Zhou, 2022, A new species and new species group of Sweltsa Ricker, 1943 (Plecoptera: Chloroperlidae), Zootaxa 5154 (1), pp. 60-70 : 64-67

Sweltsa sp. AZH-1

( Figs. 5–8 )

Adult habitus: Triocellate. General color green, pale yellow in ethanol. Head pale with black circular spot, compound eyes dark, ocellar margins with black rings ( Fig. 5A ). Antennae pale, but distal flagella become brown. The pronotum disk bears a dark black medial stripe ( Fig. 5A ). Mesonotum and metanotum medially bear a dark brown U-shaped mark with a dark medial stripe ( Fig. 6A ). Wings membrane transparent, legs pale. Abdominal tergum 1 with anterior and lateral margins brown, terga 2–4 with a wide rectangular median stripe, terga 5–8 with triangular median stripe; stripe of tergum 8 covering an anterior one-third of the segment. Terga 2–8 each with a pair of distinct pale median spots ( Fig. 6A ). Cerci pale consist of nine segments and are covered with long brown setae.

Male: Body length 9.5–10.5 mm, forewing length 8.0– 8.5 mm, hindwing length 7.0– 7.5 mm (n = 2). Tergum 9 is slightly sclerotized, anteriorly with two connected median brown elliptical stripes, transverse ridge absent ( Fig. 5B ). In ventral aspect, tergum 9 forming a trapezoidal subgenital plate, posterior margins truncate ( Fig. 5D ). Tergum 10 with sclerotized transverse bands, the medial portion between the bands greatly enlarged in a shield-like basal anchor, the anchor much longer than wide and with a typical membranous groove ( Fig. 5B ). Epiproct narrow and long, rod-like in the dorsal aspect, sub-apically slightly widened with a rounded tip; apex smooth, bearing a sclerotized cap ( Fig. 7A ); the cap is inflated upward in lateral aspects. Most of the dorsal and ventral surface is covered with brown appressed setae and mostly parallel-sided in outline and subapically widened laterally ( Figs. 7A–D ).

Female: Body length 10.0 mm, forewing length 8.5 mm, hindwing length 7.5 mm (n = 1). Habitus is generally similar to the male, but the ocellar area and frons are darker than the male ( Fig. 8A ). Abdominal tergum stripes are the same as males except for tergum 8 with median brown elliptical stripe; lateral dark patches also present anteriorly on segments 2–4 ( Fig. 6B ). The posterior margin of sternum 8 bears a rounded subgenital plate in ventral view, reaching near the half of the sternum 9 and weakly sclerotized. The subgenital plate posteromedially bears long hairs; the posterior tip of the plate is not rounded and possesses a minute notch in the middle ( Figs. 8C–D ).

Nymph and egg: Unknown

Material examined: 2 males, 1 female, China, Sichuan Province, Anzihe Nature Reserve, Shaoyaogou , 2016- VI-20, N 30. 8097, E 103.2194, 1598 m, Leg. Zhi-Teng Chen .

Distribution: China (Sichuan Province).

Remarks: These specimens are most similar to S. wui Stark & Sivec 2009 . An additional study, especially examining the type specimens of S. wui , is needed for specific placement because S. wui and our specimens were both collected from Sichuan Province and are closely similar. However, we noted some morphological differences from S. wui as follows. In our specimens, the head bears a black circular spot ( Fig 5A ), while the S. wui has a triangular spot (fig. 1 in Stark & Sivec, 2009). The epiproct of our specimens are longer, narrower, and subapically slightly widened than the previous description (compare our Fig. 7A–D with figs. 2–7 in Stark & Sivec, 2009). A distinct dark medial stripe in the U-shape pattern of mesonotae and metanotae is also missing in the S. wui description. In Stark & Sivec (2009), they described the only male of S. wui and indicated that it could be placed in another genus. We also noted that the drawing and SEM plates provided for S. wui , specifically in the shape of epiproct, have few variations. To clarify this confusion, we tried our best to check the type specimens to avoid confusion in identifying our specimens as the lowest possible taxa. Unfortunately, we did not check the types as they are present out of China.

Consequently, highlighting the above morphological differences in our new specimen, we tentatively consider this as Sweltsa sp. for the time being, because both samples were collected from the same province. In addition, there is no female record available for S. wui and our female specimen subgenital plate is rounded and bears long hairs medially ( Fig. 8D ) and is closely similar to S. colorata Zhiltzova & Levanidova, 1978 . The subgenital plate of S. colorata is subtriangular, the apex is truncate, and covered with a patch of hairs (fig. 507 in Teslenko & Zhiltzova 2009) which easily distinguish these two females. Nevertheless, what is needed is to examine the type materials of S.wui and conduct more surveys in Sichuan Province to collect a large number of specimens for further morphological and molecular studies.

Figures

FIGURE 5. Sweltsa sp. AZH-1, male. A: head and pronotum; B: terminalia, dorsal view; C: terminalia, lateral view; D: terminalia, ventral view.

FIGURE 6. Sweltsa sp. AZH-1. A: male abdomen, dorsal view; B: female abdomen, dorsal view.

FIGURE 7. Sweltsa sp. AZH-1, male. A and C: epiproct, dorsal view; B and D: epiproct, lateral view.

FIGURE 8. Sweltsa sp. AZH-1, female. A: head and pronotum; B: terminalia, dorsal view; C: terminalia, ventral view; D: subgenital plate.