Three new species, Isometopus chaiyaphum, Paloniella microchelys, and Myiomma phuvasae, of the plant bug subfamily Isometopinae Fieber are described; additional records for I. siamensis Yasunaga, Yamada & Artchawakom are documented. The habitat of P. microchelys is reported. A checklist of the isometopine fauna of Thailand is provided.
The plant bug subfamily Isometopinae Fieber is composed of very small mirids with a pair of ocelli, and together with the subfamily Psallopinae Schuh, putatively constitutes the most primitive Miridae. Isometopines are distributed globally, but the majority of species occur in the tropics, subtropics, and warm temperate climate zones.
The Isometopinae currently comprise approximately 50 nominal species in Asia (Schuh 1995, 2002−2014, Kerzhner & Josifov 1999). The Asian faunas, historically known from the works of Distant (1904, 1911) and Poppius (1913, 1915), have been augmented mainly by Lin (2004) and Lin & Yang (2004) for Taiwan, Ren (1991) and Ren & Yang (1988) for continental China, Yasunaga (2001, 2005) for Japan, and Yasunaga & Duwal (2006) for Nepal. However, the Isometopinae of Indochina, known to be one of the most species-rich regions in the world, is currently represented only by Isometopus feanusDistant, 1904 (Myanmar) and I. siamensis Yasunaga, Yamada & Artchawakom, 2013 (Thailand).
The habits of isometopines are poorly known because of their unique habitat preference for tree trunks (often under bark) or branches, which make collecting the bugs with a sweep net difficult (Wheeler 2001, Yasunaga 2005). In addition, most isometopines are assumed to be diurnal, with uv light traps attracting a limited number of specimens presumably from nearby habitats (Yasunaga 2001, 2005); therefore, few individuals come to light because isometopine population densities are inherently low in most habitats, particularly in tropical or well-preserved forests. As a result, quite a few species have been described from the holotype only. Biological information on tropical isometopines is hardly available, with many species in tropical and subtropical zones remaining undescribed.
During our continuing field investigations in Thailand, one undescribed specimen each from the genera Isometopus, Paloniella, and Myiomma were recently discovered (two by uv light traps and one from the trunk of a broadleaf tree). Herein we describe these as the new species, I. chaiyaphum, M. phuvasae, and P. microchelys. Additionally the habitat of P. microchelys is briefly documented, Isometopus siamensis is diagnosed, and a checklist of the Isometopinae from Thailand, following the classification system of Herczek (1993), is provided.
Materials and methods
Almost all specimens examined were collected at ‘Sakaerat Environmental Research Station, Sakaerat Biosphere Reserve, Ministry of Science and Technology, Nakhon Ratchasima Provinces, Thailand’ cited in the text simply as ‘sers’ (http://www.tistr.or.th/sakaerat/index_en.php). All holotypes are deposited in the Insect Collection, Entomology & Zoology Group, Plant Protection Research and Development Office, Department of Agriculture, Bangkok, Thailand (doat). Matrix code labels were attached to all type specimens, which uniquely identify each specimen, and are referred to as ‘unique specimen identifiers’ (usis). The usi codes [e.g., amnh_pbi 000123] comprise an institution and project code (amnh_pbi) and a unique number (000123). These data were digitized on the Arthropod Easy Capture (formerly the Planetary Biodiversity Inventory) database maintained by the American Museum of Natural History, New York, usa (http://research.amnh.org/pbi/), are incorporated in http:// www.discoverlife.org, and are also searchable on the ‘Heteroptera Species Pages’ (http://research.amnh.org/pbi/heteropteraspeciespage/).
Digital images of live individuals were taken by ty with a Canon eos Kiss digital camera body + Olympus om-System. All measurements are in millimeters (mm). Synonymic lists for known taxa are omitted, as comprehensive catalogs covering the necessary literature are now available (Schuh, 1995, 2002–2014, Kerzhner & Josifov 1999).
Checklist of Thai Isometopinae
Subfamily Isometopinae Fieber
Tribe Isometopini, subtribe Isometopina
Genus Isometopus Fieber, 1860
Isometopus chaiyaphum Yasunaga, Duanthisan & Yamada, sp. n. — Distribution: Thailand (Chaiyaphum).
Isometopus siamensis Yasunaga, Yamada & Artchawakom, 2013 — Thailand (Nakhon Ratchasima).
Genus PaloniellaPoppius, 1915
Paloniella microchelys Yasunaga, Duanthisan & Yamada, sp. n. — Thailand (Nakhon Ratchasima).
Tribe Myiommini Bergroth, subtribe Myiom-mina
Genus Myiomma Puton, 1872
Myiomma phuvasae Yasunaga, Duanthisan & Yamada, sp. n. — Thailand (Nakhon Ratchasima).
Subfamily Isometopinae Fieber
Diagnosis. Members of this subfamily are easily recognized by the presence of a pair of ocelli between compound eyes. General shape and size (total length 2−8 mm) variable, especially form of the head, compound eyes, antennae and pronotum (see Herczek 1993).
Discussion. Although the present work follows a classification system proposed for isometopine taxa by Herczek (1993), we encourage a revised suprageneric classification. In our opinion many undescribed taxa, especially from the tropics and subtropics, cannot be accommodated by the current system (Yasunaga unpublished data). In general, the isometopine pretarsal and male genitalic structures are fundamentally similar to those exhibited in the Psallopinae and some members of the Cylapinae (Yasunaga et al. 2010, Herczek & Popov 2014). A broader survey of these and other character systems, as well as documentation of undescribed taxa, is required to substantiate a relationship between these three subfamilies and provide an updated suprageneric classification system.
All the species of the Isometopinae are presumed to be predators, with some species having a close association with coccids (Wheeler & Henry 1978, Wheeler 2001, Yasunaga 2001, 2005). Ren (1987) reported a continental Chinese species, Isometopus citri Ren, found on citrus trees heavily infested by a scale, Unaspis sp. (Diaspididae), the assumed prey of the isometopine. On Ishigaki Island of the Ryukyus, a subtropical island of Japan, Yasunaga (2005) reported six species of the Isometopinae inhabiting (or sometimes co-occurring on) the ash tree, Fraxinus griffithii C.B. Clarke (Oleaceae). There are usually many half-detached fragments and cracks on the ash bark surface, which may provide suitable refuge from the predators of these isometopine plant bugs.
A similar habitat preference was confirmed in the psallopine, Psallops fulvioides Yasunaga & Yamada, which might support a close relationship between the Isometopinae and the Psallopinae (Yasunaga et al. 2010). Incidentally, Wolski & Henry (2015) downgraded the Psallopinae to a tribal level and placed it in the Cylapinae. As pointed out by Herczec et al. (2015), this proposal, inclusion of Psallopinae in Cylapinae at the rank of tribe, seems to require careful consideration. The identity and relationships of the Psallopinae are still poorly demonstrated, and their subfamilial status may be compromised by a more comprehensive phylogenetic assessment of the Isometopinae and Cylapinae (Cassis & Schuh 2012). Therefore, a definitive treatment of the Psallopinae (or Psallopini in Cylapinae) is beyond the scope of this study. We currently encourage much broader surveys of characters as well as their biology, to correctly ascertain a lineage between isometopines, psallopines and cylapines.
Genus Isometopus Fieber
Isometopus chaiyaphum Yasunaga, Duanthisan & Yamada sp. n.
Figs 5–8, 15, 16
Type material. Holotype, ♂: Thailand: Chaiyaphum, Chulabhom Dam, uv light trap, 760−780 m, 16°32–33’N, 101°38–39’E, 16–18 Apr 2013, T. Yasunaga et al. (amnh_pbi 00380407) (doat).
Diagnosis. Recognized by its bicolored, oval body; pale yellow-brown, translucent hemelytron and membrane; fuscous pronotum with pale posterolateral corner; and fuscous scutellum with an apical, creamy yellow, V-shaped mark at apex. Most similar in general coloration and shape to I. nagarjunYasunaga & Duwal, 2006 from Kathmandu, Nepal; distinguished by its flat posterior margin of pronotum not projecting mesally, larger apical pale mark on the scutellum, and uniformly pale, translucent hemelytron without infuscate paracuneus and base of cuneus.
Male. Body oval, widely fuscous with pale, translucent wings and creamy yellow legs; dorsal surface weakly shining, with uniformly distributed, simple, pale, semierect setae. Head weakly flattened in front; compound eye a little produced anteriad; vertex darkened medially around ocelli; buccula and clypeus shiny fuscous. Antenna creamy yellow; segments iii and iv slightly darker. Labium shiny yellowish brown, long, reaching genital segment; apical 2/3 of segment iv reddish brown. Pronotum dark brown, weakly shining, roughly punctate, with pale lateral carina and posterolateral corner; posterior margin of pronotum flat, not projecting; scutellum shiny fuscous, with a creamy yellow, V-shaped mark from median part to apex; pleura widely shiny reddish brown. Wings pale, translucent; hemelytron minutely punctate; cuneus with an obscure spot along inner margin. Pro- and mesofemora each with a brown ring at apex; metafemur with a circular spot ventrally. Abdomen entirely shiny dark brown. Male genitalia as in Figs 15, 16. Hypophysis of left paramere sharply curved at middle; right paramere with short, rather broad hypophysis. Endosoma almost totally membranous.
Measurements. Male: Total body length 2.05; length apex of clypeus to cuneal fracture 1.33; width of head across compound eyes 0.55; head height in frontal view 0.36; width of vertex 0.17; lengths of antennal segments I–iv: 0.09, 0.43, 0.30, 0.16; length of labium 1.05; mesal pronotal length 0.30; basal pronotal width 1.02; maximum width across hemelytron 1.15; and length of metafemur, tibia and tarsus 0.67, 0.67, 0.22.
Etymology. Named for its type locality, Chiyaphum Province; a noun in apposition.
Biology. Unknown; the adult male was attracted to a UV light trap.
Isometopus siamensis Yasunaga, Yamada & Artchawakom, 2013
Diagnosis. Recognized by its uniformly fuscous general coloration; deeply punctate dorsum; rather large compound eye; elongate left paramere with circularly curved, apically tapered hypophysis; and broad base of right paramere. See Yasunaga et al. (2013) for detailed description.
Biology. The adults are occasionally attracted to light. Collection records suggest this isometopine has at least two generations per year.
Material examined. 1 ♂, Thailand, Nakhon Ratchasima Prov.: sers, 14°30’27”N, 101°55’39”E, 410 m alt., light trap, 3 Jun 2012, T. Yasunaga (holotype, amnh_pbi 00379601) (doat); 1 ♀, same data, except for date 2 Jun 2012 (00379602) (tycn); 1 ♂, sers, in guestroom, 14°30’39”N, 101°55’52”E, 385 m, 13 Dec 2015 (01:50 a.m.), T. Yasunaga (tycn, without usi label).
Genus Paloniella Poppius
Paloniella microchelys Yasunaga, Duanthisan & Yamada sp. n.
Figs 1–3, 9, 10
Type material: Holotype ♀: Thailand: Nakhon Ratchasima, sers, Lannea coromandelica (Houtt.) Merr. (Anacardiaceae), on bark, 390 m alt., 14°30’38.38”N, 101°55’55.88”E, 11 Dec 2015 (14:30 p.m.), T. Yasunaga (amnh_pbi 00380408) (doat).
Diagnosis. Recognized by its ovoid, tortoise-shaped body; shiny dorsum that is minutely and sparsely punctate; very short vestiture; extremely flattened head including compound eyes slightly broadened ventrad; and narrow membrane. Similar in overall appearance to P. parallela Yasunaga & Hayashi, 2002, known only from Iriomote Island, Japan; distinguished by its smaller size, generally fuscous coloration, minute and sparse punctures on the dorsum, and higher head, which is somewhat broadened ventrad.
Female: Body almost totally fuscous, oval, tortoise-shaped; dorsal surface shiny, minutely, shallowly and sparsely punctate, with uniformly distributed, very short setae. Head tinged with maroon, strongly flattened anteriad, shallowly and irregularly punctate, somewhat broadened ventrad, narrowly carinate basally; compound eye small, flattened; ocellus contiguous to compound eye and basal carina. Antenna brown, short; segment I dark brown; median part of segment ii broadly and basal 1/4 of segment iii yellowish brown; apical brown part of segment ii a little swollen. Labium shiny chocolate brown, reaching apex of metacoxa. Pronotum anteriorly concealed by head and compound eyes, transversely rugose, narrowly margined laterally; mesoscutum and scutellum roughly and transversely rugose. Hemelytron slanting laterally; cuneus wider than long; membrane grayish brown. Legs generally short; apex of each femur, base and apex of each tibia and most of tarsi brown.
Measurements. Female: Total body length 1.84; length apex of clypeus to cuneal fracture 1.27; width of head across compound eyes 0.63 (maximum width in front 0.69); head height in frontal view 0.47; width of vertex 0.17; lengths of antennal segments I–iv: 0.08, 0.38, 0.26, 0.13; length of labium 0.86; mesal pronotal length 0.33; basal pronotal width 0.97; maximum width across hemelytron 1.24; and length of metafemur, tibia and tarsus 0.50, 0.57, 0.18.
Etymology. From Greek, mikros (= tiny) combined with chelys (= tortoise), referring to the general shape of this new species reminiscent of a tortoise.
Biology. A single female adult was found on the bark (40 cm high from ground) of an Indian ash tree, Lannea coromandelica (Houtt.) Merr. (Anacardiaceae), width about 25 cm diameter at breast height (Fig. 1). Several ant workers and small spiders were observed on the same trunk, but no suitable prey was evident.
Genus Myiomma Puton
Myiomma phuvasae Yasunaga, Duanthisan & Yamada, sp. n.
Type material. Holotype ♀, Thailand, Nakhon Ratchasima, sers, 14°30’27”N, 101°55’39”E, 410 m alt., uv light trap, 10 Dec 2015, T. Yasunaga (amnh_pbi 00380409) (doat).
Diagnosis. Recognized by its oval, somewhat flattened body; conspicuously reddish lateral margins of dorsum; comparatively small head; short antennal segments iii and iv; uniformly punctate pronotum and hemelytron; and broadened exocorium. Most similar to M. zhengiLin & Yang, 2004; readily distinguished by its more ovate body shape and conspicuously reddish dorsum, and uniformly punctate pronotum and hemelytron.
Female: Body ovate, broadened posteriorly in dorsal view; dorsal surface fuscous, with conspicuous, red lateral margins from pronotum to cuneus, shallowly and roughly punctate, with uniformly distributed, simple, pale, reclining setae. Head including compound eyes hemispheric, comparatively small. Antenna whitish brown, short; segment ii broadened, with apex sanguineous; segments iii and iv very short. Labium pale brown, slightly exceeding metacoxa; apical part of segment iv broadly darkened. Pronotum dark maroon with red margin; scutellum dark maroon; hemelytron widely dark maroon, with broadly red exocorium and cuneus; membrane pale smoky brown. Legs almost totally pale brown; apices of pro- and mesofemora narrowly sanguineous; apical half of metafemora tinged with red. Abdomen shiny reddish brown; sterna viii and ix pale brown.
Measurements. Female: Total body length 2.28; length apex of clypeus to cuneal fracture 1.52; width of head across compound eyes 0.48; head height in frontal view 0.42; width of vertex 0.09 (maximum interocular space); lengths of antennal segments I–iv: 0.07, 0.46, 0.11, 0.10; length of labium 0.91; mesal pronotal length 0.29; basal pronotal width 0.98; maximum width across hemelytron 1.30; and length of metafemur, tibia and tarsus 0.76, 0.86, 0.19.
Etymology. Named to honor Phuvasa Chanonmuang (sers), who positively supports our research activities; a noun in genitive case.
Biology. Unknown; a female adult was collected by uv light trap.
We are much indebted to Dr Charuwat Taekul (doat), Ms Phuvasa Chanonmuang (sers), and Drs Andrzej Wolski and Milosz Mazur (Opole University, Poland) for supporting our collection of specimens used in this paper. Dr Michael D. Schwartz (Agriculture & Agri-Food Canada, Ottawa, Ontario) kindly reviewed the manuscript and offered some necessary references. Thanks are extended to Dr Alfred G. Wheeler (Clemson University, sc, usa) and Dr. Dan Polhemus (associate editor, TvE) for reviewing the manuscript and providing useful comments and suggestions.
Cassis G., & Schuh R.T., 2012. Systematics, biodiversity, biogeography, and host associations of the Miridae (Insecta: Hemiptera: Heteroptera: Cimicomorpha). — Annual Review of Entomology 57: 377–404.
Distant W.L., 1904. The Fauna of British India, Including Ceylon and Burma. Rhynchota. — Vol. 2, part 2, pp. 243–503. Taylor & Francis, London.
- Export Citation
)| false , Distant W.L. 1904. The Fauna of British India, Including Ceylon and Burma. Rhynchota. — Vol. 2, part 2, pp. 243– 503. Taylor & Francis, London.
Distant W.L., 1911. The Fauna of British India, Including Ceylon and Burma. Rhynchota. — Vol. V Heteroptera: Appendix, xii+362 pp. Taylor & Francis, London.
- Export Citation
)| false , Distant W.L. 1911. The Fauna of British India, Including Ceylon and Burma. Rhynchota. — Vol. V Heteroptera: Appendix, xii+ 362pp. Taylor & Francis, London.
Herczek A., 1993. Systematic position of Isometopinae Fieb. (Miridae, Heteroptera) and their interrelationships. — Prace Naukowe Uniwersytetu Slaskiego w Katowicach 1357: 1–86.
Herczek A.,, & Popov Y.A., 2014. New psallopinous plant bugs (Hemiptera: Heteroptera, Miridae, Psallopinae) from the New Hebrides and Nigeria. — Zootaxa 3878: 366–378.
Herczek, A., , Popov Y.A., & Gorczyca J., 2015. First new fossil plant bugs of the genus Psallops Usinger, 1946 (Hemiptera: Heteroptera, Miridae, Psallopinae) from the Eocene Baltic amber. — Zootaxa 4052: 495–500.
Kerzhner, I.M., and Josifov M., 1999. Miridae Hahn, 1833. — In: B. Aukema & C. Rieger (Eds), Catalogue of the Heteroptera of the Palearctic Region, Vol. 3, Cimicomorpha ii, pp. 1–576. Netherlands Entomological Society, Amsterdam, Netherlands.
- Export Citation
)| false and Kerzhner, I.M. , Josifov M. 1999. Miridae Hahn, 1833. — In: B. Aukema & C. Rieger (Eds), Catalogue of the Heteroptera of the Palearctic Region, Vol. 3, Cimicomorpha ii, pp. 1– 576. Netherlands Entomological Society, Amsterdam, Netherlands.
Poppius B., 1913. Zur Kenntnis der Miriden, Isometopiden, Anthocoriden, Nabiden und Schizopteriden Ceylon’s. — Entomologisk Tidskrift 34: 239–260.
Poppius B., 1915. H. Sauter’s Formosa-Ausbeute: Nabidae, Anthocoridae, Termatophylidae, Miridae, Isometopidae und Ceratocombidae (Hemiptera). — Archiv für Naturgeschichte 80A(8): 1−80 (1914).
Ren, S.Z., 1987. New species and a newly recorded genus of Isometopidae from China (Hemiptera: Heteroptera). — Acta Zootaxonomica Sinica 12: 398−403 (in Chinese with English summary).
Ren S.Z., 1991. A new species of Isometopus Fieber from Yunnan, China (Heteroptera: Isometopidae). — Acta Zootaxonomica Sinica 16: 204−206 (in Chinese with English summary).
Ren S.Z., & Yang C.K., 1988. New genus and new species of Isometopidae from China (Hemiptera–Heteroptera). — Entomotaxonomia 10: 75−82 (in Chinese with English summary).
Schuh R.T., 1995. Plant Bugs of the World (Insecta: Heteroptera: Miridae). Systematic Catalog, Distributions, Host List and Bibliography. — The New York Entomological Society, New York, NY, USA, xii + 1329 pp.
Wheeler A.G. jr, 2001. Biology of the Plant Bugs (Hemiptera: Miridae), Pests, Predators, Opportunists. — Cornell University Press, Ithaca, NY, USA & London, UK, xv + 507 pp.
- Export Citation
)| false jr, 2001. Wheeler A.G. Biology of the Plant Bugs (Hemiptera: Miridae), Pests, Predators, Opportunists. — Cornell University Press, Ithaca, NY, USA & London, UK, xv + 507 pp.
Wheeler, A.G. jr & T.J. Henry, 1978. Isometopinae (Hemiptera: Miridae) in Pennsylvania: Biology and descriptions of fifth instars, with observations of predation on obscure scale. — Annals of the Entomological Society of America 71: 607–614.
Wolski A., & Henry T.J., 2015. Review and a new subfamily placement of the plant bug genus Isometocoris Carvalho and Sailer, 1954 (Hemiptera: Heteroptera: Miridae), with the description of a new species from Brazil. — Proceedings of the Entomological Society of Washington 117: 407−408.
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)| false & Wolski A. , Henry T.J. 2015. Review and a new subfamily placement of the plant bug genus. — Proceedings of the Entomological Society of Washington IsometocorisCarvalho and Sailer, 1954 (Hemiptera: Heteroptera: Miridae), with the description of a new species from Brazil 117: 407− 408.
Yasunaga T., 2001. Family Miridae Hahn, plant bugs. — In: T. Yasunaga, M. Takai & T. Kawasawa (Eds), A Field Guide to Japanese Bugs ii, pp. 1–96, 111–351. Zenkoku Noson Kyoiku Kyokai, Publishing Co. Ltd., Tokyo, Japan (in Japanese).
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)| false , Yasunaga T. 2001. Family Miridae Hahn, plant bugs. — In: T. Yasunaga, M. Takai & T. Kawasawa (Eds), A Field Guide to Japanese Bugs, pp. ii 1– 96, 111–351. Zenkoku Noson Kyoiku Kyokai, Publishing Co. Ltd., Tokyo, Japan (in Japanese).
Yasunaga T., 2005. Isometopine plant bugs (Heteroptera: Miridae) preferably inhabiting Fraxinus griffithii on Ishigaki Island of the Ryukyus, Japan. — Tijdschrift voor Entomologie 148: 341−349.
Yasunaga T., , & Duwal R.K., 2006. First record of the plant bug subfamily Isometopinae (Heteroptera, Miridae) from Nepal, with description of a new genus and five new species. — Biogeography 8: 55−61.
Yasunaga T., , Yamada K., & Artchawakom T., 2010. First record of the plant bug subfamily Psallopinae (Heteroptera: Miridae) from Thailand, with descriptions of new species and immature forms. — Tijdschrift voor Entomologie 153: 91–98.
Yasunaga T., , Yamada K., & Artchawakom T., 2013. A new species of Isometopus Fieber, the first record of Isometopinae (Heteroptera: Miridae) from Thailand. — Zootaxa 3599: 197–200.