Eurystylus Stål

Yasunaga, Tomohide, Nakatani, Yukinobu & Chérot, Frédéric, 2017, Review of the mirine plant bug genus Eurystylus Stål from Japan and Taiwan (Hemiptera: Heteroptera: Miridae: Mirinae), with descriptions of two new species, a new synonymy and a new combinatio, Zootaxa 4227 (3), pp. 301-324: 305-306

publication ID

https://doi.org/10.11646/zootaxa.4227.3.1

publication LSID

lsid:zoobank.org:pub:62ABB516-62B1-46AF-A235-3AD772358A8A

persistent identifier

http://treatment.plazi.org/id/038987D6-FFAA-6E3D-FF2B-FF35E1B1FAE2

treatment provided by

Plazi

scientific name

Eurystylus Stål
status

 

Genus Eurystylus Stål 

Eurystylus Stål, 1871: 671  (n. gen.), type species: Eurystylus costalis Stål, 1871: 671  ( Fig. 2View FIGURE 2 F; habitus images of the holotype available on http://www2.nrm.se/en/het_nrm/c/ eurystylus  _ costalis  .html), monotypic; Schuh, 1995: 766 (cat.); Kerzhner & Josifov, 1999: 99 (cat.); Yasunaga, 2001: 233 (diag.); Zheng et al., 2004: 271 (diag., key to Chinese spp.); Schuh (2002– 2014) online catalog.

Diagnosis. Eurystylus  is distinguished from other genera of the tribe Mirini  by the following characters (whereas some of these characters are shared with the assumed related taxa, Eocalocoris Miyamoto & Yasunaga  [EC], Eurystylopsis Poppius  [EP], Heteropantilius Zheng & Liu  [HP] or Miyamotoa Yasunaga  [MY]): Body remarkably thick, box like [HP, EC, EP], generally matte or shagreened [EP]; dorsum impunctate [HP, EC, MY], with at least two types of vestiture [EP]; head weakly porrect and relatively horizontal or prognathous [HP, EC, EP, MY]; lateral margin of frons, bordering to antennal tubercle and inner margin of eye, with a fuscous, velvety mark that is usually visible even in species with darkened head ( Figs. 1View FIGURE 1 H, 2E, F); antenna, shorter than body, with segment I tumid, obviously flattened, segment II clavate (its apical part more than twice as thick as base), and segments III and IV short and filiform [HP, EC, EP, MY]; pronotum often with a pair of dark spots on disk, sometimes forming eyeshape, so-called ‘head bugs’ (as in Figs. 2View FIGURE 2 A, E; 3E); collar thickened, broader than base of antennal segment II; scutellum tumid, long, with its lateral margin length greater than basal width; each femur more or less flattened [EP]; metatibia not much longer than metafemur; male genital segment (pygophore) noticeably shortened; abdominal sterna VIII and IX in female narrow; left paramere usually strongly constricted at base of widened and flattened (often flap-like) hypophysis ( Fig. 4View FIGURE 4); endosoma with well-developed membranous lobes [EC, MY], with one to four lobal sclerites ( Fig. 5View FIGURE 5, FL, ML, PL, TL); seminal duct strongly constricted distally ( Fig. 5View FIGURE 5 C); secondary gonopore thick-rimmed, with triangular or heart-shaped aperture [EC, HP, MY]; and female bursa copulatrix with a confluent ventral labiate plate [EC, EP]. The final-instar nymph is unique in having the generally pale, ovoid, thick body with several pairs of eye-like, or ocellate spots on dorsum ( Fig. 2View FIGURE 2 B –D).

Distribution. Known from the Old World, mainly subtropical and tropical zones; most species occurring in the Ethiopian and Oriental regions; only a few members known from the Australian Region and Pacific Islands.

Biology. As evidenced by many Eurystylus  species that are collected on inflorescences, floral nectar and pollen are considered to be their major diets ( Yasunaga, 2001). Most congeners are presumed to be herbivorous and polyphagous. The immature forms of more than seven species (including some undetermined or undescribed ones from tropical Asia) were confirmed to inhabit inflorescences of various dicots (see Table 1). The adults of the species shown in Table 1 (except for E. jingfui  ) were observed to suck on flower buds, petals and/or pedicels (cf. Fig. 1View FIGURE 1 G).

In the Afrotropical Region, Eurystylus oldi Poppius  is frequently documented as a major pest of sorghums, Sorghum bicolor  (L.) Moench ( Poaceae  ) in particular, and some Eurystylus  species in South Africa were documented to feed on both male and female flowers of a castor, Ricinus communis  L. ( Euphorbiaceae  ), causing them to shrivel and die; in some cases, entire stems die (Wheeler, 2001). In Asia, no Eurystylus  member has ever been reported as an agricultural pest, even though some species actually inhabit inflorescences of economic fruit trees, and ornamental or medicinal plants (e.g., chestnuts, oranges, mangos, aralias, lilacs; Table 1). The population densities of Asian species are usually not significant, and any harmful gregarious feeding is currently not recognized.

One generation per year is assumed for Eurystylus  species inhabiting temperate and colder climate zones, whereas those in tropics, subtropics or warm temperate zone appear to have a bivoltine or multivoltine life cycle.

Discussion. Eurystylus  is easily separable from related genera by the flattened antennal segment I, a pair of fuscous, velvety spots at lateral corner on the frons, thicker collar, elongate scutellum, and shortened genital segments (male pygophore and female segments VIII and IX). These characters will distinguish Eurystylus  from taxa possessing similar facies (e.g., tumid box-like body, clavate antennal segment II), such as Eurystylopsis  known from Nepal, Taiwan and continental China, Eocalocoris  from southwestern Japan, Heteropantilius  from China and Taiwan, and Miyamotoa  originally described from the Amami Island-Group of the Ryukyus  . However, these genera equally have more smooth dorsum, cylindrical antennal segment I, nearly equilateral scutellum, and conventional mirine paramere shape, in addition to their own unique characters or autapomorphy (for further information, see Yasunaga, 1990, 1995; Yasunaga & Takai, 1994; Zheng et al., 2004). The below key equivocally distinguishes the five related genera.

Within the four genera mentioned in above generic diagnosis, Eurystylopsis  is assumed to be most closely related to Eurystylus  , because these two genera share seven diagnostic characters, as well as the largely matte dorsal surface, and similar coloration, vestiture pattern ( Fig. 9View FIGURE 9 A –B), and shape of the metathoracic scent efferent system ( Fig. 8View FIGURE 8 G –H). The phylogenetic relationship of Eurystylus  to other mirine genera will need to be further elucidated. However the shared characters of above-mentioned genera imply that at least the four genera may be originated from a same lineage; Miyamotoa  is separated from the other genera in having the reduced M-vein that represents unusual character state in the tribe Mirini  .

On the other hand, a few more superficially similar taxa appear to exist in the Old World. For instance in the Australian Region, the poorly known Pseudeurystylus clavicornis Poppius, 1915  ( Fig. 9View FIGURE 9 F), the sole representative of the monotypic genus Pseudeurystylus Poppius, 1915  , also shares similar color and vestiture patterns, clavate second antennal segment, tumid body and pronotum, and thick pronotal collar. However, Pseudeurystylus  can be distinguished easily from all above mentioned taxa by the four ivory-white, callose stripes on the pronotal lateral margin and propleuron, the pronotal collar thicker than the base of antennal segment II at middle but not laterally (the collar has the almost similar thickness throughout in Eurystylus  ) and the pronotal callosities developed and nearly contiguous to the collar. In the Ethiopian Region where more than twelve Eurystylus  species occur, Stonedahl (1995) considered the possible relationship between Eurystylus  and Volumnus Stål, 1866  (including Yambio Linnavuori, 1975), mainly based on dorsal pilosity, thick and relatively short antennal segments III and IV and the presence of “a small, plate-like process on the base of maxillary plates, ventral to antennal fossae” ( Stonedahl, 1995). However, as pointed out by Stonedahl for the vestiture (op. cit.), these character states are not considered unique, being observed in other mirine genera; the genital structures of Volumnus  are also different from those of Eurystylus  . A relationship between Eurystylus  and Volumnus  appears only superficial. To demonstrate a satisfactory phylogenetic position and sister taxa of Eurystylus  , comprehensive work treating all the Old World members is required.

In Japan and Taiwan, three species, Eurystylus coelestialium  , E. luteus  , and E. sauteri  , have been reported. However, our attempts to identify the specimens from these areas revealed that the Japanese and Taiwanese populations which have been assigned to E. luteus  should belong to E. sauteri  , and all previous records of E. sauteri  from SW Japan and Taiwan were incorrect (see below Discussion for E. ryukyus  and E. sauteri  ). Judging from the overall similarities (as in Figs. 3View FIGURE 3 A –G, 4B –I) and distribution patterns ( Fig. 7View FIGURE 7), it is highly probable that luteus  (described by Hsiao from Anhui, China in 1941) and sauteri  (by Poppius from Taiwan in 1915) are conspecific. The holotype of luteus  is unfortunately female, but the male endosomal illustrations based on Chinese materials ( Zheng & Chen, 1991; Zheng et al., 2004) doubtlessly coincide with those found in Japan and Taiwan ( Fig. 4View FIGURE 4 D –I). We therefore refrain from using luteus  for relevant Japanese and Taiwanese specimens, to avoid further taxonomic confusion.

Kingdom

Plantae

Loc

Eurystylus Stål

Yasunaga, Tomohide, Nakatani, Yukinobu & Chérot, Frédéric 2017
2017
Loc

Eurystylus Stål, 1871 : 671

Zheng 2004: 271
Yasunaga 2001: 233
Kerzhner 1999: 99
Schuh 1995: 766
Stal 1871: 671
Stal 1871: 671
1995