Bifaciomiris Kim & Park & Jung 2020, gen. nov.
Creators: name: Kim, Junggon
name: Park, Haechul
name: Jung, Sunghoon
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hemiptera
Miridae
Bifaciomiris

description: Bifaciomiris Kim & Jung, gen. nov.
Diagnosis: Differs from most genera of Mirini by the following combination of characters: relatively small size (<4 mm); head two-colored with pale brown frons and entirely dark brown clypeus, mandibular plate and maxillary plate; vertex with shallow longitudinal sulcus and shallow carina posteriorly; frons glossy, covered with sparse golden setation; single compound eye narrower than vertex width, suture delimiting mandibular and maxillary plate not reaching inferior margin of eye; second antennal segment entirely dark, fourth antennal segment longer than third segment; labrum shorter than 1/2 first labial segment; apex of labium exceeding hind coxae, basal part of first labial segment dark brown; pronotum entirely yellowish brown with reflection of dark coloration under pronotum, with weak punctuations; scutellum entirely dark brown and flattened, dark coloration reaching to dark inner part of clavus, with weak punctuations; dark patterns in postero-lateral part and in posterior part of corium, patterns connecting each other; cuneus with dark marking in anterior part; tibial spines dark, without dark spots at bases (Figs. 1 A–G), left paramere with medially curved apex of hypophysis and protuberant sensory lobe, sensory lobe dentate (Figs. 2A, 3A); hypophysis of right paramere medially curved, apically tapering (Figs. 2B, 3B); endosoma mostly sclerotized, membranous reduced, with five to six sclerites and one scythe-shaped spicule (Figs. 2 C–D, 3C–E); and sclerotized rings of dorsal labiate plate large, almost adjoining to each other; not surpassing interramal lobe to interramal sclerites, medially projected interramal lobe, rounded lateral lobe positioned on interramal lobe in posterior wall (Figs. 2 E–G, 3F–H).
Description: Body oval, relatively small in size being around 3.0– 3.5 mm, glossy, covered with tiny punctures. COLORATION: almost brownish with dark markings. Head: two-colored, frons pale brown, clypeus, mandibular and maxillary plates dark brown; antennae mostly brown, first segment almost pale brown, second segment entirely dark brown. Thorax: pronotum pale brown with reflection of dark coloration under pronotum; scutellum entirely dark brown; hemelytra mostly yellowish brown with dark patterns in posterior part; inner part of clavus dark brown; corium with dark markings in postero-lateral part and in middle of posterior part; inner part of cuneus dark brown, apex of cuneus dark brown; legs yellowish pale brown, femur with darker rings subapically. Abdomen: entirely dark brown. SURFACE AND VESTITURE: body glossy, covered with long setae; head covered with long setae; antennal segment with densely short setae; pronotum with tiny punctures and short setae; scutellum with tiny punctures, covered with setae; hemelytra with both long and short setae, with dense punctures; legs with dense setae; tibia with spines and erect setae. STRUCTURE: Head: hypognathous, width longer than length of head; carina shallow posteriorly; vertex with shallow sulcus, shorter than first antennal segment length; compound eye narrower than vertex, suture delimiting mandibular and maxillary plate not reaching inferior margin of compound eye; antennae cylindrical; first and second segments thicker than others; first segment shorter than head width; second segment slightly thicker gradually toward its apex; third segment shorter than fourth segment; labrum shorter than 1/2 first labial segment; labium exceeding hindcoxae. Thorax: posterior margin of pronotum convexly angled; scutellum flattened laterally; lateral margin of hemelyron rounded; length of cuneus as long as width; membrane longer than length of cuneus; legs generally slender; third tarsal segment longer than others. Abdomen: reaching to apex of cuneus. Male genitalia: left paramere as long as right paramere; left paramere scythe-shaped, hypophysis medially curved, sensory lobe developed and projected upwardly, with tooth-like structures (Figs. 2A, 3A); right paramere generally straight, with curved and tapering hypophysis(Figs. 2B, 3B); endosoma mostly sclerotized, membranous parts reduced, with six to seven sclerites, secondary gonopore wider than ductus seminis (Figs. 2 C–D, 3C–E). Female genitalia: sclerotized rings closed each other; interramal lobe not surpassing to interramal sclerites, interramal lobe medially projected, lateral lobe rounded, positioned on interramal lobe in posterior wall (Figs. 2 E–G, 3F–H).
Type species: Bifaciomiris koreanus sp. nov.
Etymology: From the prefix Bi- (as in double) and facio-, derived from the Latin word Faciem (face) combined with ‘ Miris’ the type genus of the tribe, referring to the double colored face, one of the diagnostic characters of this genus; gender masculine.
Discussion: This new genus is similar to many genera with a Lygus -like habitus, especially groups possessing superficially similar dorsal morphology. Here, we chose genera with similar habitus morphology in three topics to focus our discussion: i) similar habitus with different paramere structures; ii) similar habitus with similar left paramere; and iii) similar habitus with similar right and left parameres and endosomal structure. See comprehensive studies such as Eyles (1999) and Yasunaga et al. (2002) for comparison with more genera and for details within a nominal group, previously called the Lygus complex, including descriptions and illustrations.
Bifaciomiris gen. nov. is similar in general appearance to genera, Apolygopsis Yasunaga, Schwartz and Chérot, Apolygus China, Chilocrates Horváth, Dagbertus Distant, Eolygus Poppius, Heterolygus Zheng and Yu, Koreocoris Cho and Kwon, Neolygus Knight, Nepiolygus Yasunaga, Schwartz and Chérot, Lygocorides (Ryukyulygus) Yasunaga, Pachylygus Yasunaga, Peltidolygus Poppius, Prolygus Carvalho and Salignus Kelton. However, this new genus can be easily distinguished by the combination of a relatively small body (except for Dagbertus and Prolygus), tumid scutellum (for Pachylygus and Peltidolygus), developed sensory lobe and structure of hypophysis of the left paramere, much less membranous and unique endosomal structure described above (e.g. Yasunaga 1991; Schwartz 1994; Yasunaga 1996; Schwartz & Foottit 1998; Yasunaga & Schwartz 2000; Yasunaga et al. 2002; Cho & Kwon 2008; Kim & Jung 2016). This genus is also similar to the genera Cyphodemidea Reuter, Iberolygus Kim, Goula and Jung, Liocoris Fieber, Lygus Hahn, Orthops Fieber, Sabactiopus Zheng and Lin, Sabactus Distant, and Warrisia Carvalho in appearance and left paramere structure. The new genus can be distinguished from the genera Cyphodemidea, Lygus, and Orthops by the first antennal segment distinctly longer than vertex width, pronotum with indistinct tiny punctuations, entirely dark scutellum and dark inner margin of clavus, right paramere structure with long and not coiled hypophysis, and reduced membranous endosoma with unique structures of spicule and sclerites (Schwartz & Foottit 1998; Schwartz & Eyles 1999). Even though color variations of head and scutellum in Lygus and Orthops are relatively well studied (e.g. Schwartz & Kerzhner 1997; Schwartz & Foottit 1998; Schwartz & Eyles 1999), the coloration patterns of the head and scutellum with the clavus of Bifaciomiris gen. nov. are clear to be the important characters. Iberolygus, recently described from Western Palaearctic is different from dorsal coloration, shape of right paramere, endosomal structure and female genitalia of Bifaciomiris gen. nov., even though structure of left paramere is similar (Kim et al. 2019). The other genera can be also distinguished from the other genera easily by the external and endosomal characters described above as diagnostic characters of the genus (Wagner 1974; Yasunaga et al. 2002; Zheng & Lin 2002). Bifaciomiris gen. nov. is similar to the Oriental genus Liistonotus in the general appearance and in genital structures of male and female. However, it can be distinguished by small body size (<ca. 3.5 mm), entirely dark clypeus, mandibular plate and maxillary plate, mostly yellowish hemelytron with small dark pattern, length of cuneus as long as width, and presence of scythe-shaped spicule in endosoma. It is also clear that a scythe-shaped spicule is found in endosoma of Bifaciomiris gen. nov. only (Figs. 2 C–D, 3C–E), although the genitalia of male of only one species Liistonotus melanostoma have been described (Schwartz & Kerzhner 1997; Zheng & Lu 2002), and descriptions of male genitalia of each study are not same. Given the difference of illustration sets of both species by each study, future study is needed whether these two species are conspecific.
The genus Liistonotus, meanwhile, consists of two species described at a time by same author: the type species L. xanthomelas Reuter, 1906 and L. melanostoma (Reuter, 1906). Reuter (1906) erected this genus based on the female specimen of Liistonotus xanthomelas, and described the species Liocoridea melanostoma at first based on female specimen also. Hence, the male characters of Liistonotus had been unknown before Schwartz & Kerzhner (1997) revised some species. Schwartz & Kerzhner (1997) compared Liocoridea melanostoma with Lygus minutus, and then synonymized latter to former, describing male genitalia of latter species. At the same time, the species Liocoridea melanostoma was transferred to the genus Liistonotus, which is the different from Reuter (1906)’s view, based on several external characters shared with Liistonotus xanthomelas and the assumption (see Schwartz & Kerzhner (1997) for details). Finally, the genitalic structure of this genus was unveiled indirectly. However, the external characters mentioned as the evidence for genus transfer, actually as characters of Liistonotus, are also found in another genus Koreocoris (based on direct examination) which possesses the totally different endosomal structures to those of Liistonotus melanostoma, although external morphology of Koreocoris was not addressed in detail in its original description (Cho & Kwon 2008). It means that there can be more groups sharing the same states, and/or L. xanthomelas might be congeneric with K. bicoloratus (based on comparison with photographs of a holotype specimen of L. xanthomelas and specimens of K. bicoloratus). As a result, provided external characters excluding genital morphology are not enough for genus transfer of L. melanotoma. In agreement with the view of Reuter (1906), it is conceivable; If the structure of male genitalia of the type species L. xanthomelas is revealed to be different to that of L. melanostoma, in other words, these two species are actually not in same genus, the placement of L. melanostoma can be changed again to where its genital structure fits. And this new genus, at the moment, can accommodate L. melanostoma, because the first genus Liocoridea was synonymized to Chilocrates which possesses the apparently different genital structures (Yasunaga & Schwartz 2000). Indeed, L. xanthomelas is also very similar externally to Koreocoris bicoloratus with similar body size. But, each body length of two Liistonotus species is quite different (L. xanthomelas: 5.75 mm; L. melanostoma: 3.2–4.0 mm in Zheng et al. 2004), and the length of body is one of the major diagnostic characters for generic level (Yasunaga et al. 2002). In order to address this situation taxonomically, comprehensive revision including these genera is needed, but it is beyond the scope of this contribution. Thus, we propose the need for future study of genera and species indicated here. As a result, it is reasonable to erect Bifaciomiris gen. nov. as the first step, based on the clear morphological characters of two species to be defined, and considering the taxonomic issues of the related group Liistonotus, as Zheng et al. (2004) pointed out that further revision of Liistonotus is needed.
This new genus, at least for the moment, might be most closely related with the genus Liistonotus based on genitalic morphology. However, some cases within Mirinae based on phylogenetic analysis genera with similar genital morphology were found to be closely not related (e.g. Phytocoris and Adelphocoris; and Orthops and Lygus), and genera with different genital morphology were recovered to be closely related (e.g. Koreocoris and Lygocorides; and Capsus and Stenotus) (Kim & Jung 2019). Therefore, future phylogenetic study using additional data such as molecular sequences is needed to evaluate relationship of Bifaciomiris gen. nov.
description: Published as part of Kim, Junggon, Park, Haechul & Jung, Sunghoon, 2020, Bifaciomiris gen. nov., a new genus of the subfamily Mirinae (Hemiptera: Heteroptera: Miridae), with description of two new species, pp. 557-565 in Zootaxa 4759 (4) on pages 558-560, DOI: 10.11646/zootaxa.4759.4.6, http://zenodo.org/record/3741086