Isometopus siamensis Yasunaga & Yamada

Yasunaga, Tomohide, Yamada, Kazutaka & Artchawakom, Taksin, 2013, A new species of Isometopus Fieber, the first record of Isometopinae (Heteroptera: Miridae) from Thailand, Zootaxa 3599 (2), pp. 197-200 : 197-199

Isometopus siamensis Yasunaga & Yamada , n. sp.

( Figs. 1–3 )

Diagnosis. Readily recognized by the generally shiny blackish basic coloration, large compound eye, infuscate antennal segment I, and form of the parameres. Sexual dimorphism is minor ( Fig. 1 ). The present new species is most closely related to a continental Chinese I. puberus Ren, 1991 , from which it can be distinguished by the above mentioned characters. Isometopus siamensis is at first sight confusable with certain species of the Anthocoridae , e.g. Wollastoniella parvicuneis Yasunaga or W. rotunda Yasunaga & Miyamoto (see Yamada et al., 2010), but any isometopine always has the closed membrane cell as in other mirid bugs ( Fig. 2 A).

Description. Body generally blackish chestnut brown, rounded oval; dorsal surface shining, densely punctate, with uniformly distributed, pale, simple, reclining setae ( Fig. 1 ). Antenna mainly yellow, with densely distributed, long, erect setae, especially on thickened segment II; segment I fuscous; segments III and IV filiform. Labium shiny chestnut-brown, long, reaching apex of metacoxa. Pronotum short, about 1/3 as long as wide, with finely and narrowly upturned anterior margin; thoracic pleura wholly fuscous; apex of scutellum attaining near base of membrane. Hemelytron shiny dark brown; cuneus somewhat paler in dried specimens; membrane sombre brown, with narrow, single-celled venation. All coxae and femora shiny chestnut-brown; metafemur tumid, lamellate; apex of each femur, and all tibiae and tarsi yellowish-brown; tarsus 2-segmented ( Fig. 3 B). Abdomen shiny chocolate-brown. Male genitalia ( Figs. 2 C, 3C–E): Parameres hairless, long, slender; left paramere with elongate base; endosoma almost entirely membranous.

Measurements (3/ Ƥ). Total body length 1.71/ 1.86; head width across compound eyes 0.74/ 0.74; head height 0.38/ 0.37; vertex width 0.25/ 0.25; lengths of antennal segment I-IV 0.12, 0.45, 0.25, 0.17/ 0.11, 0.42, 0.25, 0.16; labial length 0.88/ 0.89; mesal pronotal length 0.37/ 0.38; basal pronotal width 1.10/ 1.10; width across hemelytron 1.30/ 1.30; lengths of metafemur, tibia and tarsus 0.55, 0.63, 0.15/ 0.49, 0.74, 0.20.

Etymology. Named for its occurrence in Siamese country, or Thailand.

Distribution. Thailand (Nakhon Ratchasima Prov.).

Biology. Unknown; all known specimens were collected by a light trap. As documented by Wheeler (2001) and Yasunaga (2001, 2005), the isometopines are known particularly to inhabit barks of various trees and are presumably diurnal. Within the Isometopinae , the present new species is unusual, having a phototactic habit.

Holotype. 3, THAILAND: Nakhon Ratchasima Prov.: SERS, 14˚30 27″N, 101˚5539″E, 410 m alt., light trap, 3 Jun 2012, T. Yasunaga ( AMNH _PBI 00379601) ( SUT).

Paratype. 1Ƥ, same data as for holotype except for date 2 Jun 2012 (00379602) ( TYCN).

Figures

FIGURE 1. Habitus images of Isometopus siamensis, living individuals taken at SERS. A, Holotype male (AMNH _ PBI 00379601); B, paratype female (00379602).

FIGURE 2. Ventral images of Isometopus siamensis. A, Holotype male (AMNH _ PBI 00379601); B, paratype female (00379602); C, pygophore of holotype.

FIGURE 3. Isometopus siamensis. A, Apical part of right forewing of paratype female (AMNH _ PBI 00379602); B, apical part of paratype female foreleg; C − E male genitalia of holotype (00379601): C, right paramere; D, left paramere; E, aedeagus.