Suwallia decolorata Zhiltzova & Levanidova, 1978

Li, Weihai, Murányi, Dávid & Shi, Li, 2015, New species records of Suwallia Ricker, 1943 (Plecoptera: Chloroperlidae) from China, with description of the nymph of S. decolorata Zhiltzova & Levanidova, 1978, Zootaxa 3994 (4), pp. 556-564 : 557-561

Suwallia decolorata Zhiltzova & Levanidova, 1978

( Figs. 1 a, 2–4)

Suwallia decolorata Zhiltzova & Levanidova, 1978 : Zhiltzova & Levanidova 1978. Novie Vidi Zivotnih, Akademia Nauk SSSR Trudy Zoologiceskogo Instituta, 61: 16; Alexander & Stewart 1999. Transactions of the American Entomological Society, 125: 199; Teslenko & Zhiltzova 2009. Key to the Stoneflies (Insecta, Plecoptera ) of Russia and Adjacent Countries: 85.

Material examined. 82♂, 107♀, 205 nymphs (78♂, 102♀, 198 nymphs in HIST 4♂, 5♀, 7 nymphs in HNHM): CHINA: Inner Mongolia Autonomous Region, Genhe City, Hanma National Nature Reserve, Central Protection Station at bridge of Bonuo River, 1.viii.2014, leg. Li Shi, Mingrun Tian, Yuxuan Zhu, Xuefeng Gao and Chao Chen.

Description of the Chinese specimens. Male ( Figs. 1 a, 2). Forewing length 7.4–7.7 mm. Head pale without markings or stigmata. Pronotum pale yellow with brown anterior and lateral bands ( Fig. 2 a). Median abdominal stripe trapezoid-shaped on each tergum ending at posterior margin of tergum 8 ( Figs. 1 a, 2b).

Terminalia ( Figs. 2 ). Tergum 9 slightly produced at posterior margin, with a shallow medial concavity and partially overhanging anterior portion of tergum 10. Tergum 10 with slender medial triangular sclerite. Hemitergal processes finger-shaped typical for genus, covered with fine hairs. Epiproct small and hairy ( Figs. 2 b–d). Aedeagus in lateral view before eversion with a prominent hook-shaped sclerite ( Fig. 2 d), armature of triangular spines forming a T-shaped structure consisting of an anterior transverse bar and a wide, elongate longitudinal bar; the anterior bar straight or curved in a shallow V ( Figs. 2 c, 2f). Basoventral lobe large and subquadrate with tiny spinules, spines located on posterolateral corners larger.

Female: Forewing length 9.8–10.2 mm. Median abdominal stripe ending at tergum 7. Subgential plate large and broad, the basal portion attaching to sternum 8 wide, then narrowing posteriorly to semicircular portion, apex reaching to the posterior margin of sternum 9. Paraprocts small and triangular.

Mature larva ( Figs. 3–4 ): Body length not including antennae and cerci, 8.8–9.3 mm. General color brownish yellow to brown. Head brown, M-line indistinct, compound eyes set in line with the ocelli ( Figs. 3 a, 3c). Lacinia with single terminal tooth, about ¼ Χ as long as total length of outer margin, with ca. 30 inner marginal bristles, those on the apical ½ stouter ( Fig. 4 a). Right mandible with only inner marginal row of medial bristles ( Fig. 4 b).

Pronotum with anterior and posterior marginal setae: setae more prominent and dense at corners, setal row interrupted medially at anterior margin; a single mesolateral seta present on each lateral side above the coxa of foreleg ( Figs. 3 a, 3c). Legs with fine posterior hair fringe on both femora and tarsi, femora covered by long, appressed hairs ( Fig. 4 c). Wingpads typical of family and without distinct pattern; posterior margin diverging from body axis and outer margins slightly convex ( Fig. 3 c). Mesosternal Y-ridge with long stem, arms reaching posterior corners of furcal pits; all thoracic sterna with distinct and dense chloride cells ( Fig. 4 d).

Abdominal sterna 8 and 9 with median gaps in posterior hair fringe. Cerci with 15 segments. Segments 1–5 wider than long, following segments longer than wide and increasing in length, tapering; apical setae on median and apical segments erect and nearly as long as the segment.

Diagnosis and Remarks. Alexander & Stewart (1999) mentioned that in this species the head and body are usually unpigmented, but occasionally with a faint, median abdominal stripe. However, the illustration of this species by Alexander & Stewart (1999) indicated unpigmented abdominal terga. A diagnostic feature of this species is the membranous aedeagus bearing a T-shaped sclerotized spinose patch. Our specimens show a more distinctive body pattern and the anterior bar of sclerotized T-shaped aedeagal armature appears as a shallow Vshaped structure on some specimens.

We originally considered our material to represent a new species because of these distinct differences in body color and aedeagal armature. After Dr. Teslenko provided us her unpublished photos indicating similar features of Russian populations of this species, we considered our specimens to represent S. decolorata exhibiting similar variation of body coloration and aedeagal armature. Dr. Teslenko did mention that aedeagal variation may be associated with body coloration in the Russian populations (V. Teslenko, personal communication). However, in our specimens, the body coloration appears consistent, but the anterior aedeagal transverse bar varies as with the Russian specimens.

The larvae are typical of the genus in the setation of the pronotum and cercal hairs ( Stewart & Stark 2002). However, the mandible lacks the ventral rows of bristles usually found in other Chloroperlinae genera ( Stewart & Stark 2002). Among the Asian species of Suwallia , only the larva of S. teleckojensis was been described ( Zhitzova & Teslenko 1997). Compared to that species, the cerci of S. decolorata bear much longer apical setae.

Figures

FIGURE 1. Dorsal view of male habitus—a: Suwallia decolorata Zhiltzova & Levanidova, 1978; b: Suwallia talalajensis Zhiltzova, 1976.

FIGURE 2. Male of Suwallia decolorata Zhiltzova & Levanidova, 1978 — a: Head and pronotum, dorsal view; b: Terminalia before eversion, dorsal view; c: Terminalia with extruded aedeagus, dorsal view; d: Terminalia before eversion, lateral view; e: Extruded aedeagus, lateral view; f: Variation of everted aedeagal armature, dorsal view.

FIGURE 3. Larva of Suwallia decolorata Zhiltzova & Levanidova, 1978 — a: Head and pronotum, dorsal view; b: Right cercus, lateral view; c: Habitus, dorsal view.

FIGURE 4. Larva of Suwallia decolorata Zhiltzova & Levanidova, 1978 — a: Right lacinia, dorsal view; b: Right mandible, ventral view; c: Right foreleg, dorsal view. c: Mesosternum, ventral view.