Temnostethus mirificus, Yamada & Yasunaga, 2021

Yamada, Kazutaka & Yasunaga, Tomohide, 2021, The tribe Anthocorini in Japan (Hemiptera: Anthocoridae): descriptions of new species, review of distribution and bionomics, Acta Entomologica Musei Nationalis Pragae 61 (2), pp. 375-426 : 381-382

Temnostethus mirificus sp. nov.

( Figs 1C–D , 2B,D , 3E–H , 18 )

Type locality. Japan, Aichi Prefecture, Toyota-shi, Odo-cho, riverbed of Yahagi-gawa River.

Type material. Hඈඅඈඍඒඉൾ: J ( Figs 1C–D ), ‘[JAPAN:AICHI] \ Toyota, Odo \ (Yahagi Riv.) \ 15-June-2012 \ M. YAZAKI leg.’ [printed], [a card with locality data in Chinese script, printed]; mounted on a triangular card, in intact condition ( TKPM). Pൺඋൺඍඒඉൾඌ: JAPAN: HඈඇඌHඎ: Tochigi Pref.: 1 ♀, Sano-shi, Mt. Karasawa, 26.vi.2020, S. Maehara ( TKPM). Chiba Pref.:1J 1♀, Matsudo-shi, Sendabori, 4.x.2014,N.Muro ( TKPM). Aichi Pref.: 1 ♀, same locality as holotype, 17.vi.2007, M. Yazaki ( TKPM); 4 JJ (one in Fig. 2D , one in Figs 3E–G ) 6 ♀♀ (one in Fig. 2B , one in Fig. 3H ), same data as holotype ( TKPM, TYCN); 3 JJ 2 ♀♀, same locality as holotype, 18.vi.2013, M. Yazaki.

Differential diagnosis. Recognized by the following combination of characters: body ( Figs 1C–D ) always brachypterous, generally blackish brown; labium roughly reaching abdominal sternum III; hemelytra ( Fig. 1C ) mostly dark brown to blackish brown, with anterior half of corium brown to light brown; claval suture vestigial; costal fracture and membrane completely absent; hind wing greatly reduced; paramere ( Figs 2D , 3E–G ) slender, straight or very slightly curved but curved at apex, with longitudinal groove in form of shallow depression; apex of paramere reaching to approximately halfway along the outer margin of pygophore. Distinctive among Temnostethus species in having only the brachypterous form characterized by the vestigial claval suture and the lack of a membrane. The morphology of the hemelytra clearly distinguishes the new species from other congeners. In general appearance, the new species is most similar to the brachypterous form of T. gracilis , but it is distinguished from the latter by the primarily dark brown to blackish-brown hemelytra (in T. gracilis , brownish with pale band on anterior portion of corium), the yellowish-brown tibiae being apically tinged with fuscous (in T. gracilis , entirely pale yellow), and the paramere being slender and straight or very slightly curved (in T. gracilis , stout, and moderately curved).

Description. Coloration. Body ( Figs 1C–D ) generally blackish brown. Head ( Fig. 1C ) blackish brown to dark orangish brown; clypeus sometimes yellowish brown; eyes and ocelli reddish black; margin of ocellus red to reddish brown. Antennal segment I uniformly blackish brown; segment II yellowish brown on basal 2/3, fuscous distally; segments III and IV fuscous ( Figs 1C–D ). Labium ( Fig. 1D ) yellowish brown to dark brown. Pronotum and scutellum ( Fig. 1C ) entirely blackish brown. Hemelytra ( Fig. 1C ) mostly dark brown to blackish brown; anterior half of corium brown to light brown. Legs ( Fig. 1C ) yellowish brown; coxae, trochanters, and femora darker brown; tibiae apically tinged with fuscous. Venter of thorax and abdomen ( Fig. 1D ) uniformly blackish brown. Pygophore blackish brown with pale yellow paramere ( Figs 1C–D ). Ovipositor and area around ovipositor brown to light brown.

Structure. Body ( Figs 1C–D ) oblong oval, shiny on dorsal and ventral surfaces. Head ( Fig. 1C ) cylindrical, impunctate, slightly longer than width across eyes, sparsely covered with suberect, yellowish setae; three pairs of long, erect trichobothria on the dorsal surface of the head, one on anterior clypeus, one in front of eye, and one between eye and ocellus; anteocular region approximately twice as long as length of eye in dorsal view; vertex approximately 2.7 times as wide as width of eye in dorsal view in male, 4.0–4.5 times as wide as width of eye in female; postocular region weakly constricted, demarcated by transverse shallow furrow; neck long, smooth, highly polished; eye not exceeding level of dorsal and ventral surface of head in lateral view. Antennae ( Figs 1C–D ) densely covered with short, decumbent, yellowish setae interspersed with long, erect setae, of which the longest are as long as or slightly shorter than width of corresponding segment; segment I not reaching apex of head, sparsely covered with short setae; segment II gradually thickened toward apex, male thicker than female, approximately 1.2 times as long as head width across eyes; segment III 0.52–0.55 as long as segment II; segment IV longer than segment III. Labium ( Fig. 1D ) reaching to approximately abdominal sternum III, sparsely covered with short, suberect setae; segment III medially constricted in ventral view, moderately curved in lateral view, approximately twice as long as or longer than segment II; segment IV approximately 0.5 times as long as segment III.

Pronotum ( Fig. 1C ) flattened, with a pair of long, erect trichobothria on midline of collar; anterior margin weakly concave, slightly shorter than mesal length; lateral margin sinuate, anteriorly rounded; lateral carina strongly expanded anteriad; collar short, transversely rugose, with scattered, yellowish setae; callus not swollen, impunctate; posterior lobe behind callus sparsely covered with suberect, yellowish setae and punctures; posterior margin concave, wider than twice the anterior margin. Scutellum ( Fig. 1C ) sub-equilateral, slightly wider at base than long, deeply depressed posteriad; anterior half smooth, posterior half strongly rugose. Hemelytra ( Fig. 1C ) attaining abdominal tergum III, sparsely covered with suberect, yellowish setae, and with punctures on posterior part of corium and along inner margin of clavus; costal margin and medial fracture strongly convex; claval suture vestigial (weakly demarcated by shallow groove); costal fracture and membrane completely absent; hind wing greatly reduced. Ostiolar peritreme ( Fig. 2B ) broad, very slightly curved anteriorly at apex, continued by a fine carina that reaches anterior margin of metapleuron; outer margin of ostiolar peritreme weakly raised above level of surrounding evaporatorium. Legs covered with sparse suberect, yellowish setae; fossula spongiosa present, but very small on apex of protibiae, indistinct on meso- and metatibiae.

Abdomen ( Figs 1C–D ) covered with recumbent, yellowish setae; dorsal laterotergites not fused with mediotergites on abdominal segment II.

Male genitalia ( Figs 2D , 3E–G ): Pygophore ( Fig. 3E ) broadly cone-shaped, somewhat flattened, covered with 5–7 long, stout setae intermixed with short, suberect setae along outer margin and on posteroventral surface, of which the longest setae are approximately half length of pygophore; mid-dorsal surface with suberect setae; paramere ( Figs 2D , 3F–G ) slender, straight or very slightly curved but curved at apex, strongly bent at the base, with longitudinal groove in the form of shallow depression; apex of paramere reaching to approximately halfway along outer margin of pygophore.

Female genitalia ( Fig. 3H ): Copulatory tube fused on middle of intersegmental membrane between sterna VII and VIII, approximately 0.15 mm in length, basally thickened, and gradually narrowed toward apex, with weak rugosities at basal 1/3; sperm pouch large; trunk of conductive tissue not pronounced (or possibly dissolved).

Measurements [mm;JJ (n = 5) / ♀♀ (n = 9), holotype in parentheses]. Body length 2.25–2.45 (2.45) / 2.30–2.70; head length (excl. neck) 0.42–0.46 (0.45) / 0.44–0.48; head width across eyes 0.41–0.44 (0.44) / 0.39–0.45; vertex width 0.24–0.26 (0.26) / 0.26–0.29; length of antennal segments I – 0.14–0.15 (0.15) / 0.13–0.15, II – 0.51–0.56 (0.56) / 0.45–0.51, III – 0.26–0.30 (0.30) / 0.25–0.28, and IV – 0.31–0.34 (0.33) / 0.30–0.34; length of labial segments II – 0.32–0.35 (0.32) / 0.34–0.40, III – 0.63 (unmeasurable) / 0.68–0.75, and IV – 0.30 (unmeasurable) / 0.31–0.34; anterior pronotal width 0.34–0.36 (0.36) / 0.34–0.38; mesal pronotal length 0.36–0.38 (0.37) / 0.35–0.40; basal pronotal width 0.70–0.79 (0.75) / 0.70–0.83; length of hemelytron 0.54–0.66 (0.60) / 0.48–0.67; maximum width across hemelytra 0.90–1.02 (0.97) / 0.90–1.05.

Etymology. From Latin, mirificus (= strange, amazing), referring to the vestigial wings of the new species, which represent an unknown morphological condition among its congeners; an adjective.

Bionomics. Temnostethus mirificus sp. nov. is associated with lichens on the trunk surface of deciduous broadleaf trees, similar to the habitat of its congeners. This new species was collected from only three localities in the Tochigi, Chiba and Aichi Prefectures, Honshu. In Tochigi, one female specimen was collected from the trunk of Quercus species covered with lichens and/or mosses (Satoshi Maehara, pers. comm.). The Aichi population of T. mirificus was found along the riverbank of the Yahagi- -gawa River in a low mountainous area (Mitsuhiko Yazaki, pers. comm.). The Chiba population was discovered in an urban park, where its habitat appears to be restricted to a few broad-leaved trees (Noriyuki Muro, pers. comm.). This area, prior to its conversion into a park, used to be a paddy field at the bottom of a valley surrounded by deciduous forests. Presumably, T. mirificus may prefer the border areas around mountain foothills and the rural areas of low mountains; however at present, we have insufficient data to determine whether or not the Chiba population is native. Regarding the species’ phenology, according to Muro’s observations, active adults (walking or mating) and active nymphs (walking) were present for six months between the middle of June to early December. Consequently, univoltine or bivoltine life cycles are assumed for this species; however, no detailed information is available on the overwintering stage.

Distribution. Japan: Honshu: Tochigi, Chiba, Aichi. This species is endemic to Japan, representing only three populations known to date from Tochigi, Chiba, and Aichi Prefectures ( Fig. 18 ).

Figures

Fig. 1. Habitus, dorsal (A, C, E) and lateral (B, D, F) views. A–B – Temnostethus distans Kerzhner, 1973, female; C–D – T. mirificus sp. nov., holotype, male; E–F – Elatophilus nipponensis Hiura, 1966, male. Scale bars: 1.0 mm.

Fig. 2. Scanning electron micrographs of diagnostic characters of Japanese anthocorids. A – Temnostethus distans Kerzhner, 1973, female; B, D – T. mirificus sp. nov., female (B) and male (D), paratypes; C – Elatophilus nipponensis Hiura, 1966, female. A–C – ostiolar peritreme and evaporatorium, left lateroventral view; D – pygophore with paramere, lateral view. Abbreviations: eva ‒ evaporatorium; mf ‒ median furrow; op ‒ ostiolar peritreme; prm ‒ paramere; pyg ‒ pygophore.

Fig. 3. Male (A–C, E–G, I–K) and female (D, H, L) genitalia. A–D –Temnostethus distans Kerzhner, 1973; E–H – T. mirificus sp. nov., paratype; I–L – Elatophilus nipponensis Hiura, 1966.A, E, I – pygophore with paramere (ejaculatory bulb omitted), dorsal view; B–C, F–G, J–K – paramere, two different views; D, H, L – copulatory tube and sperm pouch (D, L, sperm pouch broken off), dorsal view. Abbreviations: ct ‒ copulatory tube; prm ‒ paramere; pyg ‒ pygophore; sp ‒ sperm pouch. Scale bars: 0.1 mm.

Fig. 18. Distribution of Temnostethus distans Kerzhner, 1973 (circles), T. mirificus sp. nov. (triangles), and Elatophilus nipponensis Hiura, 1966 (squares) in Japan. Filled symbols represent records based on specimens examined by us, open symbols represent literature records.