Namtokocoris sitesi Vitheepradit, 2017

Vitheepradit, Akekawat, 2017, A new species of Namtokocoris Sites (Hemiptera: Naucoridae) from Thailand, Zootaxa 4320 (3), pp. 592-596 : 593-595

Namtokocoris sitesi Vitheepradit , NEW SPECIES ( Figs. 1 , 2 )

Description. Macropterous male. Holotype, length 7.68; maximum width 4.88. Paratypes (n = 5), length 7.24–8.08 (mean = 7.63); maximum width 4.59–5.12 (mean = 4.89). Overall coloration dorsally dark brown with yellowish brown head, pronotum, and wide band at anterior end of embolium gradually narrowing posteriorly and becoming obsolete near distal end of embolium; heavy dark punctation forming distinct pattern on head and pronotum, heaviest between eyes and pronotum behind eyes forming yellowish-brown Y-shaped pattern in middle ( Fig. 1a ). Ventrally, generally golden brown; yellowish on anteclypeus and lateral margins of prothorax.

Head length 1.28, maximum width 2.96, synthlipsis at posteromesal corner 1.10, with three pairs of setal rosettes near inner margin of eyes. Antennal proportions 5:6:14:10. Pronotum broad, 2.8× as wide as long; length at midline 1.68; maximum width at posterolateral corners 4.72; posterolateral corners rounded, slightly produced posteriorly ( Fig. 1a ). Scutellum dark brown, heavily punctate, triangular with distinctly sinuate lateral margins, about twice as wide as long, width 2.56, length 1.20. Claval commissure length 1.48. Embolium evenly curved, yellowish anterior band gradually narrowing posteriorly and becoming obsolete near distal end of embolium, length 3.20 (chord measurement), maximum width 0.80. All coxae yellowish, trochanters and femora golden brown, fore tibia and tarsus dark brown, middle and hind tibia and tarsus golden brown. Leg measurements as follows: foreleg, femur 1.84, tibia 1.16, tarsus 0.36; middle leg, femur 1.84, tibia 1.34, tarsomeres 1–3 0.12, 0.30, 0.30; hind leg, femur 2.46, tibia 2.20, tarsomeres 1–3 0.28, 0.72, 0.74. Posterior margin of mediosternite III straight, IV–VIII concave. Posterior margin of laterosternite V sinuate. Genital operculum with posterolateral margins straight, apex rounded. Parameres bluntly acute, apices not surpassing lanceolate median process of pygophore; pygophore triangular with a rounded tip; aedeagus with mid-dorsal carina, left margin mostly straight with distinct convexity in distal fifth, right margin slightly convex in basal 4/5 and concave in distal fifth to parallel convexity of left, series of striations in basal half on right of mid-dorsal carina ( Fig. 1b ).

Macropterous female. Paratype (n = 1), length 8.60; maximum width 5.36. Similar to male in general structure and coloration; weakly-developed lateral lobe on costal margin of right hemelytron at position of abdominal segment V; pad of hairs on middle tibia reduced; posterior margins of mediosternites V, VI straight; subgenital plate (VII) with lateral margins convergent, slightly convex at posterior margin ( Fig. 1c ).

Diagnosis. This species can be recognized by the lanceolate median process of the pygophore and the apically curved aedeagus without a hook in the male, and the straight posterior margin of mediosternite VI and slightly convex subgenital plate (mediosternite VII) in the female. More specifically, N. sitesi can be distinguished from N. akekawati , N. minor , and N. siamensis by the posterolateral corners of the pronotum produced posteriorly, whereas the latter species have the corners rounded, but not produced posteriorly. Namtokocoris sitesi can be distinguished from N. khlonglan by the claval commissure as long as the pronotum, median process of the pygophore lanceolate, and apices of the parameres not surpassing the median process, whereas the latter species has the claval commissure longer than the pronotum, median process of the pygophore rounded at apex, and anterolateral corners of parameres extending beyond the median process of pygophore.

Discussion. This species was found in the water film and fine roots on near-vertical rock surfaces of Krating Waterfall, Khao Khitchakut National Park, Thailand. The type locality ( Fig. 2 ) is located in the Khao Soi Dao Mountain Range in the eastern region of the country. Namtokocoris sitesi was collected syntopically with Onychotrechus esakii Andersen ( Heteroptera : Gerridae ). I have attempted to collect this species numerous times at the type locality and at different tiers of the same waterfall, and nearby waterfalls in the Khao Soi Dao Mountain Range from 2011 to 2012; however, no additional adult specimens were collected, although a nymph of Namtokocoris was collected along with a species of Dermaptera. Males of this species are most similar to N. kem from Nghe An Province ( Vietnam) and Nan Province (northern Thailand) based on genitalic structure, and females to N. minor from Kanchanaburi Province ( Thailand) based on the terminal abdominal segments. However, this species is clearly distinct morphologically and geographically. Modification of the key in Sites & Vitheepradit (2007) by creating a trichotomous couplet 4 as follows will enable identification of N. sitesi n.sp.

4''. Claval commissure subequal in length to pronotum at midline. Female with weak lateral lobe on costal margin of right hemelytron at position of abdominal segment V .................................................................................... Namtokocoris sitesi Vitheepradit

Etymology. This species is named in honor of Robert W. Sites (University of Missouri, Columbia, U.S.A.) in acknowledgment of his great contributions on the taxonomy of aquatic and semiaquatic Heteroptera , especially Naucoridae and Aphelocheiridae .

Material examined. Holotype, macropterous male (UMC): THAILAND: Chanthaburi Province, Khao Khitchakut National Park, Namtok Krating , tier 2, 13°10'N 102°46'E, 523 m, 13 January 2011, rock face of waterfall, Vitheepradit, Maitreepaen, Pinkaew, C-21 . Paratypes: same data as primary type (2 macropterous males KU; 3 macropterous males, 1 macropterous female UMC).

Figures

FIGURE 1. Diagnostic features of Namtokocoris sitesi n. sp. a) dorsal habitus of holotype, b) genital capsule of male, c) terminal abdominal sterna of female.

FIGURE 2. Krating Waterfall in Chanthaburi Province, Thailand, the type locality of Namtokocoris sitesi n. sp.