Schiodtella formosana Takano & Yanagihara 1939

Schiodtella formosana (Takano & Yanagihara, 1939)

(Figs. 17–30, 37–39)

Neostibaropus formosanus Takano and Yanagihara, 1939: 135, pl. 4, fig. 19. Type locality: Taiwan.

Diagnosis. Head strongly wrinkled in dorsum (Figs. 18, 19); eyes very small (Figs. 18, 19); ocular index 13.5–16. Scutellum short and rounded, almost as long as wide (Fig.17). Peritreme lacking apical process (Fig. 20). Tarsi absent from all legs (Figs. 22–25, 37–39). Median arm of basal plate of penis shorter than lateral arms (Fig. 26); conjunctival appendage strongly protruding from phallotreme and recurved downwards in rest (Fig. 27).

Description. Male: ― total length 4.25–4.65; total width 2.8–3.0; body 2.35–2.5 high; head 0.95–1.0 long, 0.92–0.95 wide; length of antennal segments I 0.2, II 0.3–0.32, III 0.2–0.22, IV 0.35–0.38; length of rostral segments I 0.4, II 0.45, III 0.3–0.32, IV 0.32; pronotum 1.44–1.52 long, 2.36–2.7 wide; scutellum 1.85–1.95 long, 1.8–1.95 wide; hemelytron 2.8–2.86 long.

Body yellowish brown to brown; dorsum of head and anterior part of pronotum blackish. Eyes reddish; ocelli orange to reddish. Antennae and rostrum yellowish brown. Hemelytral membranes hyaline. Legs yellowish brown; apical half of protibia and corbicle of metatibia blackish.

Total length about 1.5 times as long as total width, 1.8 times as long as body height. Head (Figs. 18, 19) slightly longer than wide, strongly wrinkled in dorsum; clypeus (Fig. 18) slightly shorter than paraclypei; paraclypeus (Figs. 18, 19) fringed with 7–10 peg-bearing tubercles, and with several setae anteroventrally; primary setae III–V (Figs. 18, 19) peg-like, thinner than secondary ones. Eyes (Figs. 18, 19) very small, weakly prominent; ocular index 13.5–16; ocellar index 6.5; interocellar index 3.3–3.5. Antenna covered with thin, sparse setae in segments I and II, and dense setae in III and IV; approximate proportion of segments I to IV 1.0: 1.5: 1.0: 1.8. Rostrum surpassing procoxae; approximate proportion of segments I to IV 1.3: 1.5: 1.0: 1.0. Pronotum (Fig. 17) distinctly wrinkled in anteromedial part and posterior half, mixed with punctures in posteromedial part, and with 14–19 setae on lateral margin and 1 seta behind callus (Fig. 16), on each side. Scutellum (Fig. 17) short, rounded apically, almost as long as wide, entirely wrinkled. Thoracic pleura smooth except evaporatoria; peritreme without apical process (Fig. 20). Hemelytron (Fig. 17) short, not reaching tip of abdomen; corium (Fig. 17) indistinctly covered with fine punctures and wrinkles, and with 6 or 7 setae on costal margin; clavus (Fig. 17) with 1 seta basally. Protibia (Fig. 22) covered with setae between proximal 2/5 and distal 1/5 of anterior side, and with 5 spines on tibial edge. Setae of mesotibia gradually becoming longer and stouter toward tibial apex in anterior and dorsal sides (Fig. 23). Hind leg (Figs. 24, 25) considerably stout; setae on tibia gradually becoming longer and stouter toward corbicle; corbicle bearing stout spines, with 1 rough, longitudinal line of spines. Tarsi absent from all legs. Abdominal sternites III to VII moderately covered with setae of various length and thickness, especially in lateral part. Genital capsule with medial process on apicoventral margin. Penis (Figs. 26, 27) with strongly sclerotized and pigmented theca; median arm of basal plate shorter than lateral arms (Fig. 26); conjunctival appendage strongly protruding from phallotreme and recurved downwards in rest (Fig. 27). Paramere (Figs. 28–30) somewhat elongate, moderately covered with setae; hypophysis sharpened (Figs. 28–30).

Female: — not available in this study.

Material examined. 23, Chiwei, Chishan, Kaohsiung Hsien, Taiwan, 4.II.1934, M. Yanagihara leg. (ELKU).

Distribution. Taiwan is the definite locality of this species at present, because previous distributional records are most probably erroneous for mainland China and Japan.

Remarks. The most remarkable characteristic of Sc. formosana is the absence of tarsi from all legs, which easily distinguishes this species from the other members of Schiodtella. Regarding the peculiarity of this characteristic for its taxonomic value, Takano and Yanagihara (1939) appear to have established the new genus Neostibaropus to accommodate the simultaneously described species N. formosanus (= Sc. formosana). Actually, the lack of tarsi is considered a notable feature worthy of establishing a new genus for not only this species but also any other species of Scaptocorini. However, Sc. formosana has several important characteristics which are common to other congeners of Schiodtella, such as the four-segmented antennae, the peg-bearing tubercles fringed along the margin of the paraclypeus, and the abdomen with a 1+1 trichobothrial formula on the sternites III to VII, as documented by Lis (1999) and Lis and Hohol-Kilinkiewicz (2001). In addition to these characteristics, the penis structure may be sufficiently distinct for this species to be included in Schiodtella. Every species of this genus possesses the conjunctival appendage on the venter of the endosoma of the penis. The appendage serially varies from externally invisible as in Sc. secunda (Lis 1991b) to large and long as in Sc. japonica sp. nov. through medium-sized as in Sc. laevicollis (Montandon 1897) and Sc. subglabra (Breddin 1900). The appendage of Sc. formosana is large and long, being most similar to Sc. japonica sp. nov. among the congeners of Schiodtella. The range of variation in the appendage, then, also allows Sc. formosana to remain in Schiodtella. Perhaps Sc. formosana is more closely related to Sc. japonica sp. nov. than the other species of Schiodtella.

The absence of tarsi from all legs is also observed in the Afrotropical Afroropus bocagei (de Carvalho 1969) and the Neotropical Atarsocoris giselleae (= A. macroptera). However, Sc. formosana is separable from these two species by the paraclypeus fringed with peg-bearing tubercles.