Loricula Curtis, 1833

Yasunaga, Tomohide, Yamada, Kazutaka & Ohno, Tomohide, 2020, A new species of the genus Loricula Curtis from central Honshu, Japan (Heteroptera: Microphysidae), Zootaxa 4759 (1), pp. 98-106 : 99-101

Genus Loricula Curtis

Loricula Curtis, 1833: 197 , type species by monotypy: L. pselaphiformis Curtis, 1833: 197 ; Henry, 1988: 250 (cat.); Péricart, 1996: 79 (cat.); Yasunaga, 2001: 111 (diag.); Aukema et al., 2013: 75 (cat.); Yasunaga & Yamada, 2017: 1211 (diag.): Yasunaga et al., 2018: 168 (diag.); Aukema, 2018 (online cat.).

Diagnosis: East Asian species of the genus Loricula are recognized primarily by: Moderate to large size (1.5–3.0 mm in total length but females much shorter than 2.4–3.0 mm in macropterous males); basic coloration brownish, partly or sometimes largely reddish; always sexually dimorphic; male adult always macropterous whereas female rounded, either coleopteroid ( Figs. 2 , 3A ), micropterous ( Fig. 4K ) or staphylinoidy; antennal segment II usually longer than IV; female pronotum trapezoid or campanulate, with more or less projected posterior angle (except for micropterous form with truncate pronotum); scent gland with narrow evaporative area ( Fig. 3F ); male forewing membrane with corial process (cf. Yasunaga & Yamada, 2017; Yasunaga et al. 2018); and male parameres more or less asymmetrical. Further diagnostic characters were provided by Yasunaga & Yamada (2017).

Distribution. Palearctic and Nearctic regions (mostly temperate and cold temperate climate zones; Nearctic populations are considered to have been introduced) ( Yasunaga & Yamada 2017).

Discussion. Loricula species are dominantly recorded from the western Palearctic Region ( Yasunaga & Yamada, 2017). Because of its tiny size, restricted distribution and obscure habits, this genus has hardly been studied. The male adults resemble anthocorids, whereas the females have remarkable wing polymorphism. Following a category of heteropteran wing forms suggested by Henry (2012) and Schuh & Slater (1995), most of the female adults of Japanese Loricula species are coleopteroid (only L. nikko is micropterous). In Japan, five congeners are now known. However, two species, L. mikawa sp. nov. and L. nikko , are currently represented only by females.

As suggested by Yasunaga & Yamada (2017), the females of Loricula species appear to complete its whole life cycle in the litter at the forest floor and, therefore, it is usually difficult to collect the female specimens in good number. The females were observed to crawl up on the low vegetation (mostly ferns, cf. Fig. 1D ), mossy stones or fungous rotten logs probably for contact with the males during a limited breeding season (from June to July in Japan mainland). Incidentally, the female adults of L. mikawa sp. nov. were found on tree trunks ( Fig. 1C ) at night.

Careful observation using a tabletop SEM documented significant interspecific differences on the surface structures of the forewing (hemelytron) between four species ( Fig. 5 ). Variation in the pattern of granulate microstructures is noted for L. pilosella and L. yakushima —densely distributed, L. miyamotoi —sparsely distributed, and L. mikawa sp. nov. —absent.

Although little is known about biology and immature forms of microphysid bugs, the eggs are remarkably large-sized as in Fig. 6I , comparing with those of other heteropterans (cf. Yasunaga & Yamada, 2017; Yasunaga et al., 2018).

Figures

FIGURE 1. Habitat (A, B) and habitus image of female adult (C) for Loricula mikawa sp. nov. (A–C) and L. miyamotoi Yasunaga & Yamada (D). A & B. Secondary evergreen broadleaf forest in Toyoda City where L. mikawa occurs. C. L. mikawa, female. D. Well-preserved deciduous forest, habitat of L. miyamotoi (Yamanashi Prefecture, Japan). D: Image courtesy of T. Ishikawa.

FIGURE 2. Habitus images of Japanese Loricula species (adult females). A–C. L. mikawa sp. nov. (A: dorsal view, B: ventral view, C: right lateral view). D. L. miyamotoi Yasunaga & Yamada, dorsal view. E. L. yakushima Yasunaga & Yamada, dorsal view.

FIGURE 3. Scanning electron micrographs for female of Loricula mikawa sp. nov. A. Dorsal habitus. B. Head, dorsal view. C. Anterior body, ventral view. D. Apex of labium, ventral view. E. Vestiture pattern on ventral surface of hemelytron. F. Scent efferent system. G. Protarsus and grooming comb. H. Mestatarsus. I. Apex of abdomen, ventral view.

FIGURE 4. Scanning electron micrographs for Japanese Loricula species (adult females). A–C. L. mikawa sp. nov. D–F. L. miyamotoi. G, H. L. pilosella. I, J. L. yakushima. K, L. L. nikko. A, D, G, I & K. Anterior body, dorsal view. B, E & L. Ditto, left lateral view. C, F, H & J. Posterolateral process of pronotum.

FIGURE 5. Scanning electron micrographs for dorsal surface structure of female forewing (hemelytron). A. L. mikawa sp. nov. B. L. miyamotoi. C. L. pilosella. D. L. yakushima.

FIGURE 6. Compound microscopic images showing detailed morphology for L. mikawa sp. nov., female. A. Head and pronotum, dorsal view. B. Antenna. C. Labium. D. Thorax, ventral surface. E. Forewing base. F. Abdomen, ventral view. G. Apodemal process. H. Genital segments, ventral view. I. Three eggs found in abdomen (F).