Zherikhinia matobai sp. nov.

[Japanese name: Matoba-chibi-zômushi]

(Figs. 1–3)

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Diagnosis. This species can be distinguished from the related species Z. distylia by the following external characteristics: body length smaller than 1.8 mm; pronotum and elytra glossy, with few hairs; pronotum with serrated line bordering base; femora each with two teeth, one tooth large, the second one very small, grain-like, distal. Aedeagus constricted at about the midlength. Temones about 1/3 as long as the aedeagal body.

Description. Male. Measurements (n=5): TL 1.56–1.72 (holotype 1.72; mean 1.64); LP 0.44–0.58 (0.58; 0.49); WP 0.67–0.73 (0.67; 0.7); LE 1.12–1.2 (1.14; 1.15); WE 0.8-0.91 (0.86; 0.86); LR 0.62–0.67 (0.62; 0.64).

Derm reddish to dark reddish-brown, on head, extreme apex of rostrum, pronotum, apical segments of antennae, lateral parts of elytra, anterior parts of femora, claws, meso-, and meta-thorax; cream yellow to reddish-brown on dorsal side of elytra, legs, rostrum, but almost always with first elytral interval with dark reddish-brown line. Vestiture of white to yellowish hair-like scales, fasciate on pronotum and elytra, meso-, and metathorax.

Forehead between eyes with two rows of scales, almost touching in middle. Rostrum about 1.3 times as long as pronotum, with five longitudinal dorsal carinae, one of them (median) weak. Antennae inserted at apical third of rostrum; funicles 5-segmented, 1st segment longer than 2nd, 4th segment asymmetrical and a little longer than 3rd, 5th segment subequal to 3rd; club little longer than funicle, length of 1st and 2nd segments combined subequal to length of 3rd segment.

Prothorax about 0.7 times as long as wide, with serrated line bordering base of pronotum. Elytra about 1.3 times as long as wide, widest just behind humeri, base densely minutely crenulate; interstriae very smooth, shallow between bases of scales.

Abdomen with suture between ventrites IV and V visible, functional; ventrite V with a pair of round projections at apex.

Profemora each with two teeth on inner arc, one tooth large, the second grain-like, very small; protibia straight, mucro short, slender.

Tegmen with parameroid lobes united, not emarginate at apex, lacking median notch; each parameroid lobe with marginal row of eight long setae; posteguim with two longitudinal reinforcements, bidentate to bifid. Aedeagus with pedon symmetrical, sightly downcurved at tip, constricted at about midlength. Tectum less than half-width of pedon, slender, inflated at apex. Temones about 1/3 times as long as penis. Endphallus with denticles in median part. Internal sac at orifice with two curved sclerites. Flagellum about 2.0 times as long as temones, reaching middle of penis. Spiculum gastrale with pair of lobes shaped like double-edged ax, slightly asymmetrical.

Female. Measurements (n=5; in mm); TL 1.66–1.77 (mean 1.71); LP 0.5–0.56 (0.53); WP 0.73–0.78 (0.75); LE 1.12–1.25 (1.18); WE 0.9–0.95 (0.92); LR 0.76–0.86 (0.8). Almost all external structures similar to those of male except the following: rostrum about 1.5 times as long as pronotum (about 0.53 mm); antennae inserted at mid-length of rostrum. Abdomen with ventrite V without a pair of round projections; suture between ventrites IV and V weak but visible (Fig. 13). Ovipositor with gonocoxites about 2 times as long as spiculum ventrale; tergite VIII with short robust setae along front margin; coxite with a few oscula at tip; styli cylindrical, much smaller than coxite. Spiculum ventrale with basal plate weakly sclerotized, with thin rod-like apodeme. Bursa copulatrix simple, not developed. Spermathecal duct relatively long, at base with spiral structures, not convoluted near spermatheca. Spermatheca C-curved, robust.

Variation. This species has the following three variations in the elytral pattern: yellow, brown, blackish-brown types (figs. 22–24). The specimens collected from Okinawa-jima Island were of the yellow type. The brown type was collected mainly from Ishigaki-jima and Iriomote-jima Island, and a few specimens were collected from Kume-jima Island. A few specimens of the blackish-brown type were collected from the Okinawa-hontô and Iriomote-jima Islands. However, the number of specimens examined is too small to discuss any patterns in the variation and it is necessary to collect additional specimens for further studies.

Type material. Holotype: male, Maesetake, Ishigaki-jima Is., Okinawa Pref., Japan, 15.III.2015, I. Matoba leg (KUM). Paratypes: [Japan: Ryukyu Archipelago] 2 males, Kume-jima Is., Okinawa Pref., 29.III.1996, I. Matoba leg. (MAT); 1 male, Yarabutake, Ishigaki-jima Is., Okinawa Pref., 29.III.1999, I. Matoba leg. (KUM); 1 male, Mt. Ôtake, Kume-jima Is., Okinawa Pref., 20. IV.2021, R. Nakamura leg. (KUM); 1 male, Darumayama park, Kume-jima Is., Okinawa Pref., 20. IV.2021, R. Nakamura leg. (KUM); 2 females, Komi, Iriomote-jima Is., Okinawa Pref., 28.XII.2004, I. Matoba leg. (MAT); 1 female, Kume-jima Is., Okinawa Pref., 29.III.1996, I. Matoba leg. (MTA); 1 female, Mt. Yonahatake, Okinawa-jima Is., Okinawa Pref., 23. IV.2000, I. Matoba leg. (KUM); 1 female, Ushiku forest, Iriomote-jima Is., Okinawa Pref., 11.III.1964, S. Kimoto leg. (KUM); 1 female, Darumayama Park, Kume-jima Is., Okinawa Pref., 20. IV.2021, R. Nakamura leg. (KUM).

Etymology. The specific name is in honor of Mr. Isao Matoba who collected the type specimens of this new species.

Distribution. Japan (Ryukyu Archipelago: Okinawa-jima, Kume-jima, Ishigaki-jima and Iriomote-jima Islands).

Biology. Details of the biology are unknown although many adults were collected on Castanopsis sieboldii (Makino) (Fagaceae), which is a potential host plant.

Comments. Alonso-Zarazaga (1990) compared Zherikhinia (= Psix Alonso-Zarazaga, 1989) with Meregallia Alonso-Zarazaga, 1990 when he established the latter genus. They share the plesiomorphic characteristics of the10th stria complete, the lack of crenulation on the 8th interstria, the strongly carinate rostrum and the strongly clavate and toothed femora. Furthermore, both genera share one apomorphy: dorsal eyes which touch along the midline (Alonso-Zarazaga, 1990). Later, Kantoh & Kojima (2011) mentioned that species of Zherikhinia differ from those of Meregallia in the following additional apomorphic characteristics: the female rostrum with five longitudinal dorsal carinae (only four in Meregallia); the 8 th crenulation absent (present in Meregallia); the tegminal basal plate on the parameroid lobe with 6–8 setae (about 20 setae in Meregallia); the spermathecal duct convoluted near the bursa copulatrix (convoluted near the spermatheca in Meregallia). However, Lyal & Curran (2003), in a paper overlooked by Kantoh & Kojima (2011), described the longitudinal dorsal carina of the rostrum and the presence of the 8 th crenulation, otherwise, they did not describe the convoluted spermathecal duct and the several tegminal parameroid setae.

The new species Zherikhinia matobai lacks the diagnostic characteristic of Zherikhinia sensu Kantoh & Kojima (2011) of the spermathecal duct not convoluted near the bursa copulatrix (table 1). The description of Zherikhinia was based on the type species only, therefore the definition of this genus, which now encompasses this second species, may need to be revised after more species are found.