Gestroiella siamensis, Dan & Polhemus & John & Polhemus & Sites, 2008

Dan, Polhemus, John, Polhemus & Sites, Robert, 2008, A Revision Of The Indochinese Genera Cheirochela And Gestroiella Heteroptera Naucoridae And A Review Of The Tribe Cheirochelini, Raffles Bulletin of Zoology 56 (2), pp. 255-279 : 275-276

Gestroiella siamensis new species

( Figs. 18 , 28, 30 , 33 , 35 )

Description. – Brachypterous male (n = 10): Length: 12.78–14.11 mm, width: 8.22–9.13 mm maximum width across embolium or abdominal segment 3. Overall appearance ovate ( Fig. 18 ).

Head yellowish. Greatest width at posterolateral angles of eyes, 4.10 mm. Head length 3.03 mm. Interocular space at middle of eye, 2.42 mm. Eye length 1.36 mm. Head extends anteriorly in front of eyes 0.82 mm. Paired dark brown lines confluent at anterior margin on midline, diverging posteriorly. Anterior margin dark brown in some specimens, especially dense just anterior to eyes. Midventral carina extending 4/5 length of head posterior to rostrum, contiguous with prosternal carina. Tuft of elongate golden setae on posterior margin at base of carina. Ratio of antennal segment lengths: 7-5-14. Rostrum dark brown, directed ventrad, short, 0.6 mm (not including protruding stylets). First visible rostral segment recessed into head capsule, not surpassing margins of genae. Ratio of 3 visible rostrum segment lengths: 5-10-16.

Thorax with pronotum yellowish throughout with broad, dark brown posterior margin, dark brown markings at anterior margin near posterolateral angles of head convexity, dark brown punctation in patterns ( Fig. 18 ). Posterolateral angles narrowly rounded. Pronotum width 7.72 mm, length 2.01 mm. Scutellum yellowish, punctate. Scutellum width 3.98 mm, length 2.30 mm. Forewings mottled with yellow and medium brown, entirely yellow in embolar regions and at midline posterior to scutellum, medium brown stripe where wings overlap at midline. Anterior and lateral margin of embolium evenly rounded and with dense row of erect yellow setae; otherwise, devoid of setae other than short peglike setae. Hemelytra extending posteriorly to middle of tergum VII, apices narrowly rounded. Hemelytra width 4.71 mm, length 8.88 mm (width measured from apex of scutellum to lateral margin of wing, length from lateral margin of scutellum directly posteriorly to wing apex).

Thoracic venter orange-yellow throughout. Carina produced to acute tip extending posteriorly to midlength of mesocoxa. Metepisternum mostly pruinose, series of ridges extending laterad, appearing regularly rugulose, posterior margin deeply sinuate. Metasternal plate between meso- and metacoxae carinate, broadly rounded posteriorly.

Legs yellowish, scattered pale setae on most segments. All coxae pruinose, differentially beset with short, dark, recumbent setae. All legs with trochanter through tarsus shining. Distal end of femur, entire tibia and tarsus medium brown. Length of profemur 3.85 mm, protibia 2.75 mm, protarsus 0.82 mm. Lengths of mesofemur, mesotibia, 3 tarsomeres I–III 3.40, 2.71, 0.22, 0.44, 0.86 mm. Lengths of metafemur, metatibia, 3 tarsomeres I–III 4.51, 4.63, 0.30, 0.76, 0.96 mm.

Dorsal abdomen yellowish with light brown posterolateral angles of terga III–V, posterior margins of terga IV–VI and most of tergite VII. Pair of abdominal scent gland openings at posterior margin of tergite III, 1/5-distance to lateral margin from midline. Posterolateral angle of segment II rounded, III acutely spinose with secondary spine anterior to posterolateral angle, spines of IV similar to those of III, but slightly smaller, V with secondary spine reduced to rounded lateral protruberance, posterolateral angles of V–VIII rounded.

Ventral abdomen with scattered pale recumbent setae throughout. Sternites II–IVgenerally yellowish, medium brown posterolaterally, V–VII medium brown posteromedially. Genital capsule and mesal portion of VI and VII orange brown. Posterior margins of sternites IV–V concave medially. Sternite VI with posterior margin convex at midline, produced to blunt point. Posterior margins of sternite VII straight at middle, of genital capsule evenly rounded.

Genitalia with pygophore produced medially into broad triangular point between parameres and covered with conspicuous mat of brown setae in middle half. Parameres symmetrical; devoid of vestiture; crossing phallotheca of aedeagus; concave, wrapping dorsad toward aedeagus; elongate, gradually tapering toward apex ( Fig. 28 ); apex slightly deflexed mesad; middle of lateral margin with broad, rounded lobe. Aedeagus with phallotheca parallel-sided until just beyond tips of parameres where lateral margins flare laterad slightly before converging toward base of vesica. Phallotheca abruptly produced laterally and broadly ovate. Dorsomedial process of male genital capsule broadly triangular, slightly produced at apex ( Fig. 30 ).

Brachypterous female (n = 10): Length: 13.78–14.44 mm, width: 8.80–9.13 mm. Colouration and setation generally same as for male. Subgenital plate broadly triangular, sides evenly concave, apex bilobate ( Fig. 33 ), width 1.46, length 1.60, clothed with fi ne, light coloured pubescence in basal half. Paratergite VII medium brown with light distal margin, pointed apically. Posterior margins of sternite V straight in middle third, concave laterally; of sternite VI evenly convex. Sternites IV–VI each with brush of brown hairs in posterior 1/3 at midline. Female subgenital plate Fig. 33 .

Macropterous form: Male (n = 10): Length: 13.78–14.94 mm, width: 8.30–9.13 mm. Female (n = 10): Length: 14.11– 15.11 mm, width: 8.30–9.13 mm. Similar to brachypterous forms with the following differences: Slightly more elongate; head and pronotum with colour pattern darker; head in front of eyes shorter; pronotum with posterolateral corners truncate; scutellum larger, raised, width and length 4.84, 3.12 mm (males), 4.92 mm, 3.28 (females); mesosternal carina reduced to rounded tumescence; each hemelytron with clavus and claval suture well defined; longitudinal suture within clavus extending from near base to apex; embolium with lateral margin sinuate.

Types. – Holotype, male, and allotype, female: THAILAND, Kanchanaburi Prov., Amphur Sangkhla Buri, Heuy Kob , 15°13'N 98°22'E, 289 m, gravel stream, 13 Apr.2002, L- 339, collected by UMC and CMU teams ( UMC) . Paratypes: THAILAND, Kanchanaburi Prov.: 26 males, 28 females, same data as holotype ( UMC NMNH, RFDB) ; 2 males, 1 female, river at Pong Phu Rawn , 14°38'N 98°31'E, 24 Feb.2002, G. W. Courtney ( UMC) . Phang Nga Prov.: 2 brachypterous males, 2 brachypterous females, Amphur Kapong, Ban Tha Na , gravel stream, 8°40'N 98°25'E, 32 m, 28 May 2003, A. Vitheepradit and Ferro ( JTPC) .

Figures

Fig. 18. Gestroiella siamensis new species, female, dorsal habitus. Drawn by Young Sohn.

Figs. 26–30. Gestroiella species, male genitalia, structural details: 26, G. insignis, paramere; 27, G. limnocoroides, paramere; 28, G. siamensis, paramere; 29, G. limnocoroides, phallotheca; 30, G. siamensis, dorsomedial process of genital capsule.

Figs. 31–33. Gestroiella species, apex of abdomen of female, ventral aspect: 31, G. insignis; 32, G. limnocoroides; 33. G. siamensis.

Fig.35. Distributions of Gestroiella species in Indochina: diamonds = G. insignis; circles = G. siamensis.