Melanotrichus thaimaritimus, Yasunaga & Duwal, 2017

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 : 284-286

Melanotrichus thaimaritimus , new species

( Figs. 4A–H , 5 , 6E–H )

Material examined. Holotype male, THAILAND: Samut Prakan, Bang Pu, N13°31′07″ E100°38′57″ E, sweepnetting Sueada maritima, 21 December 2011, T. Yasunaga ( AMNH _ PBI 00380551 ) ( DOAT) . Paratypes: THAILAND: Bangkok, Choen Tha Phae, N13°33′02″ E100°25′20″, Sueada maritima, 20 December 2011, T . Yasunaga , 2 males, 1 female ( TYCN) ; Samut Prakan, same data as for holotype, except for date 15 June 2013, 10 males, 3 females ( TYCN) ; same data, except for date 19 September 2013, 17 males, 18 females & 8 October 2013, 3 males, 7 females ( DOAT, TYCN) ; Chon Buri, Bang Saen, N13°18′11.5″ E100°55′08.8″, Sueada maritima, 27–28 March 2010, T . Yasunaga , 33 males, 43 females ( AMNH, CNC, TYCN) (3 females, 00380552) .

Diagnosis. Recognised by small, elongate oval (male) or suboval (female) body; uniformly pale green basic colouration (but easily fading to pale brown after preservation, cf. Fig. 6E vs. 6F); densely distributed sericeous, reclining, scalelike setae (but easily rubbed off as in Fig. 6E, F ); small eyes; short labium reaching middle of mesocoxa; C-shaped left paramere with blunt-tipped hypophysis and broad sensory lobe ( Fig. 5A ); inflated sensory lobe and rather wide hypophysis of right paramere; and developed female interramal lobe ( Fig. 5E ).

Description. Body generally pale green but partly or entirely stramineous brown in dry-preserved specimen, small, elongate oval (male) or suboval (female); dorsal surface weakly shiny, with densely distributed, sericeous, reclining, scalelike setae and sparsely distributed, simple, brown, semierect setae. Head short, slightly pointed in front; eyes small. Antenna pale reddish brown; segment I pale green in live or fresh specimen; segment II longer than basal width of pronotum. Labium shiny pale brown, short, reaching middle of mesocoxa; apex of segment IV darkened. Pronotum and hemelytron shiny if sericeous setae rubbed off ( Fig. 6F ); membrane semitransparent, with more or less smoky posterior part. Coxae and legs pale brown but pale green in live or fresh specimen; all tibia and tarsi pale brown; apex of each tarsus darkened. Male genitalia ( Fig. 5A–C ): left paramere curled, C-shaped, with blunt-tipped hypophysis and broad sensory lobe ( Fig. 5A ); right paramere with inflated sensory lobe and rather wide hypophysis; endosoma simple. Female genitalia ( Fig. 5D–F ): Sclerotised ring decrescent, very tiny ( Fig. 5D ); posterior wall with developed interramal lobe ( Fig. 5E ).

Measurements. Male/female: Total body length 2.45– 2.60/2.64–2.77; width of head across eyes 0.55–0.59/0.60– 0.62; width of vertex 0.28–0.30/0.37–0.38; lengths of antennal segments I–IV 0.19–0.23, 0.76–0.84, 0.65–0.72, 0.27–0.30/0.19–0.23, 0.76–0.89, 0.75–0.77, 0.33–0.36; total length of labium 0.58–0.60/0.67–0.71; basal width of pronotum 0.73–0.77/0.73–0.78; maximum width across hemelytra 0.88–0.92/0.97–1.08; and lengths of metafemur, tibia and tarsus 0.87–0.90, 1.14–1.17, 0.34–0.38/0.88–0.92, 1.18–1.26, 0.39–0.42.

Etymology. Named for Thailand, in combination with the Latin adjective maritimus [= of the sea], referring to the unique halophilic habitat of this new species; an adjective.

Biology. This species was confirmed to be associated with the breeding host Sueada maritima (L.) Dumort ( Amaranthaceae ) along the northern coast of the Gulf of Siam ( Fig. 4H ). Both adults ( Fig. 4A–D ) and immature forms ( Fig. 4E–G ) were seen almost throughout a year, and this mirid is thus assumed to have a multivoltine life cycle. However, populations were observed to decrease in the late dry season (January through February) and the hot summer season (April through May). Recently, rapid urbanisation and development of beach resorts seriously threaten and reduce the limited habitats (Sueada maritima vegetation) for this plant bug; this halophyte is officially designated as an endangered plant in southeastern Japan ( Shishido & Yasunaga, 2016).

Remarks. Judging from the similarly small size and C-shaped left paramere, this new species is assumed to be sister to M. choii (Josifov, 1976) known to inhabit Saricornia spp. and Sueada maritima in Korea, northeastern China and southwestern Japan (Hyogo and Nagasaki Prefectures) ( Shishido & Yasunaga, 2016). However, the latter species, inhabitant of temperate and cool temperate climate zones, has the shorter antennal segment II (less than basal width of pronotum), more strongly curled left paramere with acute, short hypophysis, narrower right paramere and shorter interramal lobe ( Liu & Zheng, 2014; Shishido & Yasunaga, 2016). Several additional halophilic members of Melanotrichus , associated with species of Sueada or Salicornia, are also reported in Mediterranean Europe ( Wagner & Weber, 1978) and the Nearctic Region ( Henry, 1991).

Figures

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.

Fig. 6. Habitus images of Thai orthotylines, dried specimens (except for E in live). A, Cyrtorhinus indochinanus, holotype male, ventral view; B, Cyrtorhinus indochinanus, female; C, C. lividipennis, male (Nakhon Nayok); D, C. lividipennis, female (SERS); E, F, M. thaimaritimus, male (Samut Prakan); G, M. thaimaritimus, ventral view; H, M. thaimaritimus, female (Samut Prakan).