Orthotylini Van Duzee, 1916

Yasunaga, Tomohide & Duwal, Ram Keshari, 2017, Plant bugs of the tribe Orthotylini (Heteroptera: Miridae: Orthotylinae) in Thailand, with descriptions of five new species, Raffles Bulletin of Zoology 65, pp. 280-298 : 281-282

Tribe Orthotylini Van Duzee, 1916

Discussion. The subfamily Orthotylinae is currently composed of six tribes, but Cassis & Schuh (2012) argued that the definition of the nominotypical tribe Orthotylini was uncertain due to the presence of paraphyletic groups. Many taxa within the Orthotylini possess significantly enlarged male parameres (comparing with small pygophore, cf. Figs. 2A, D , 11A ), and uniquely developed male endosomal sclerites ( Fig. 10H ) and female interramal lobes ( Fig. 12A, C ). Schuh (1974) suggested a number of recognisable natural groups, including Zanchius and its allied genera in the Orthotylini . We have sampled numerous Oriental taxa belonging to the Zanchius group (e.g., Zanchius Distant, 1904 ; Itacorides Miyamoto, 1965 ; Latizanchius Lu & Zheng, 2001 ; Malacocorisella Yasunaga, 1999 ). Nonetheless, we will treat these taxa separately in our subsequent work (Duwal & Yasunaga in prep), as Zanchius group should belong to a distinct tribe ( Cassis & Schuh, 2012). Species of the Zanchius group have unique characters that are obviously different from those of other orthotyline members, e.g., dorsally flattened head with small, anteriorly directed eyes removed from pronotum, delicate, often semitransparent forewings ( Fig. 8I ), and largely membranous endosoma with simple spiculi. Most species of the Zanchius group are considered to be predators preying predominantly on auchenorrhynchans (e.g., Liu & Zheng, 2014; Yasunaga, 1999; Yasunaga et al., 2001).

The fauna of the Orthotylini in Thailand and neighbouring countries of Indochina appears less speciose, compared with those revealed in other regions of the Old World and Pacific islands. Among more than 300 mirid species found mostly in Thailand, only 10 belong to Orthotylini . Based on available records, we presume that the Himalayas and adjacent ranges may be rich in Orthotylini . A relatively large number of Orthotylini taxa occur in southwest China, north of the Himalayan range ( Liu & Zheng, 2014) and subalpine zones of Nepal (Yasunaga & Duwal, unpublished data). Four genera, Orthotylus , Cyrtorhinus , Melanotrichus and Pseudoloxops , are now recognised in Thailand (also in Indochina); all of these are widely distributed in the Old World. Owing to the lack of Palearctic element, the Indochinese orthotyline fauna is assumed to be represented primarily by a small minority of cosmopolitan taxa (e.g., Cyrtorhinus , Orthotylus ). Among 10 described species of Cyrtorhinus , C. caricis (Fallén, 1807) is the only cool temperate zone inhabitant; eight congeners are known from Africa and Oceania ( Schuh, 2002 –2014); and C. lividipennis is widely dispersed over the Indo-Pacific region and temperate eastern Asia, possibly attributable to its unique ability for long-distance aerial migration (see Drake & Reynolds, 2012; Riley et al., 1987; Yasunaga, 1999). The finding of a new species in the present paper, C. indochinanus , presumed to be indigenous to Indochina, is significant.

Orthotylus is one of the largest genera in the family Miridae , with more than 250 described species worldwide; remarkable adaptive radiation has been documented in the Hawaii Islands, the Ethiopian and the western Palearctic Regions ( Schuh, 2002 –2014). Eight subgenera were proposed for classification of the Old World members ( Kerzhner & Josifov, 1999), but they are not applicable to the tropical and New World species, and some of them evidently require generic rank. Melanotrichus was originally proposed as a subgenus of Orthotylus (see Reuter, 1875). However, the monophyly of this group is well supported by the unique characters obviously different from those exhibited by the nominotypical Orthotylus or other related genera (tiny size; presence of both dark simple setae and sericeous scalelike setae; small eyes; short male parameres; and simple endosoma, cf. Figs. 4 , 5 ). Thus, Melanotrichus was already upgraded to generic rank (e.g., Henry & Wheeler, 1988; Wheeler & Henry, 1992). The preponderance of the evidence suggests that Melanotrichus should be treated as an independent genus, although it is clear that a comprehensive revision of these widespread taxa is needed. According to this classification of Melanotrichus , we propose the following new combinations for species occurring in the Oriental and eastern Palearctic regions (all transferred from Orthotylus ): Melanotrichus choii (Josifov, 1976) , new combination; M. convexus ( Liu & Zheng, 2014) , new combination; M. elegantulus ( Liu & Zheng, 2014) , new combination; M. leukus ( Liu & Zheng, 2014) , new combination; M. longulus ( Liu & Zheng, 2014) , new combination; M. minutus (Jakovlev, 1877) , new combination; M. orientalis ( Poppius, 1915) , new combination; M. parvulus (Reuter, 1879) , new combination; M. rubidus (Puton, 1874) , new combination; and M. schoberiae (Reuter, 1876) , new combination.

Pseudoloxops was originally proposed for a single European species, P. coccineus (Meyer-Dür, 1843) . Subsequent workers described more than 40 species; the majority of congeners are known from the Pacific islands where the genus is considered to have radiated extensively, with many species that remain undescribed ( Balukjian, 2013; Hazali, 2013; Schuh, 2002 –2014). In the Oriental Region, including subtropical climate zone of eastern Asia, Pseudoloxops is represented by 10 species ( Liu & Zheng, 2014; Yasunaga & Takai, 2017; Yasunaga et al., 2001). This work adds three new species to the Thai fauna. Many congeners exhibit two-tone, brilliant yellow-rouge pattern and species identification is usually performed by the external characters alone. However, the monophyly of Pseudoloxops is still uncertain because of excessive interspecific variation in the male genitalia (cf. Fig. 10 ).

Figures

Fig. 2. Male genitalia of Cyrtorhinus species. A–C, Cyrtorhinus lividipennis; D–G, C. indochinanus. A, D, Pygophore, dorsal view; E, Pygophore, ventral view; B, F, right paramere; C, G, left paramere. Scale bars = 0.2 mm.

Fig. 11. Male genitalia of Pseudoloxops pardellus. A, Pygophore, dorsal view; B, Pygophore, ventral view; C, left paramere; D, right paramere; E, pygophoral process; F, aedeagus.

Fig. 10. Male genitalia of Pseudoloxops hibiscus (A–D), P. lateralis (E–F) and P. leopardalis (G–J). A, G, Apex of pygophore, ventral view; F, Apex of pygophore, dorsal view; B, H, pygophore, dorsal view; C, J, right paramere; D, E, I, left paramere. Scale bars = 0.2 mm.

Fig. 12. Female genitalia of Pseudoloxops imperatorius (A, B, specimen from Okinawa, Japan) and P. pardellus (C, D), named on images.

Fig. 8. Habitus images of Thai species of Pseudoloxops and Zanchius group. A, P. ayutthaya, male; B, P. ayutthaya, female; C, P. ayutthaya, final-instar nymph; D, P. pericarti, male; E, P. pericarti female; F, P. pardellus, male; G, P. pardellus, males; H, P. pardellus, female; I, unidentified species close to Zanchius marmoratus Zou, 1987 (SERS).

Fig. 4. Habitus (A–G) and habitat (H, I) images of Thai ortotylines. A, B, Melanotrichus thaimaritimus, adult male; C, D, M. thaimaritimus, adult female; E, M. thaimaritimus, male final-instar nymph; F, M. thaimaritimus, female final-instar nymph; G, 3rd instar nymph; H, colony of a halophyte, Sueada maritima (Bang Pu, Samut Prakan), habitat of M. thaimaritimus (Bang Pu, Samut Prakan); I, Hibiscus tiliaceus tree (Ban Phe, Rayong), on which Pseudoloxops hibiscus was found.

Fig. 5. Male (A–C) and female (D–F) genitalia of Melanotrichus thaimaritimus. A, Pygophore with parameres, dorsal view; B, Pygophore with parameres, caudal view; C, Pygophore with parameres, ventral view; D, bursa copulatrix, dorsal view; E, posterior wall, anterior view; F, bursae and valvulae in ventral view. Scale bars = 0.2 mm.