Mixotrephes (Pictotrephes) pictus, Papáček & Zettel, 2011

Papáček, Miroslav & Zettel, Herbert, 2011, A new subgenus and species of Mixotrephes (Hemiptera: Heteroptera: Helotrephidae) from Laos and notes on Mixotrephes punctatus, Acta Entomologica Musei Nationalis Pragae 51 (2), pp. 397-406 : 402-404

Mixotrephes (Pictotrephes) pictus sp. nov.

( Figs. 1–6 , 9, 11–16 )

Type material. HOLOTYPE: J (brachypterous, based on structures of forewing), ‘ LAOS, CHAMPASAK prov. / Bolavens Plateau / ca. 1 km S Ban Lak 40 [vill.] / TAD YUEANG waterfall, 900-970 m / 15°10.8’N, 106°08.3’E / Jiří Hájek leg. 28.iv.2010 ’ ( NMPC) . PARATYPES: 4 ♀♀ (brachypterous, based on structures of forewing), same labels as holotype (3 ♀♀ in NMPC, 1 ♀ in NHMW).

Description. Size: Body length of male 1.30 mm, of females 1.26–1.38 mm. Maximum body width (= pronotum width) of male 0.89 mm, of females 0.88–0.94 mm. Eye index (= minimum eye distance: maximum eye width) of male 2.8, of females 2.7–2.9.

Colour ( Figs. 1–6 ): Dorsum chiefly blackish. Male ( Figs. 1–3 ) cephalonotum with pair of yellow spots near posterolateral margin and with narrow yellow lateral margins; distal margin on hemielytron yellowish, almost transparent. Female (e.g., Figs. 4–6 ) cephalonotum, mesoscutellum and hemielytra with several yellow marks of varying shape and extension. Venter of head and thorax mostly yellowish brown, of abdomen dark brown. Legs dark yellow.

Structural characteristics of brachypterous morph: Head part of cephalonotum with sparse, small punctures, shiny, only at sides weakly tuberculate. Pronotal part of cephalonotum and mesoscutellum tuberculate, each tubercle sloping posteriorly, i.e. posterior slope steeper. Hemielytron with very large, deep punctures; most anterior part with a few small, intermittent tubercles. Mesoscutellum ( Fig. 9 ) wide with conspicuously convex lateral margins. Rostrum short, almost reaching level of posteroventral corner of prosternal carina; segment 4 ca. 1.5 times as long as segment 3. Forewing without claval and embolar sutures. Hindwings micropterous (examined only in one species). Midventral carinae weakly modified: Prosternal carina with almost rectangular posteroventral corner; mesosternal carina short and acute; metasternal carina with straight ventral outline, posteroventral corner weakly elevated; carinae of abdominal sterna 2–3 pointed, of abdominal sterna 4–6 present as low tubercles, on sternum 6 only in anterior part (in male less distinct than in female).

Terminalia of male ( Figs. 11–14 ): Abdominal sternum 8 ( Fig. 14 ) slightly asymmetrical, round, longer than wide, processing more caudally on the right side. Pygophore with low, rounded process.Aedeagus simple, phallosoma ( Fig. 11 ) straight, pin-shaped, slightly flattened, with tapered, bluntly rounded, unmodified apex; somewhat longer than both parameres. Left paramere ( Fig. 12 ) slightly longer that right one; basally robust with wide, round posterior lamella, distally hook-shaped with very conspicuous dense and long setae. Right paramere ( Fig. 13 ) nearly upright, apically antero-posteriorly flattened, spoon shaped; only with few minute setae on posterior surface.

Terminalia of female ( Figs. 15, 16 ): Subgenital plate (= abdominal sternum 7; Fig. 15 ) unmodified, with broad posterior lobe and only slightly concave lateral margins (this concavity only discernable under high magnification). Proximal part of this plate brown, middle and posterior area dark brown, posteromedial lobe with beige-brown, round spot at hind margin. First valvulae ( Fig. 16 ) of the Mixotrephes type, with cluster of robust, peg-shaped, both short and long, thick setae (macrotrichia) on apical lobe, and with numerous microtrichia scattered on well pigmented area proximally to this cluster (microtricha and differences in macrotrichia are visible only under high magnification of about 400× on microslide).

Comparative notes. Mixotrephes (Pictotrephes) pictus sp. nov. differs from all congeners by coarse sculpture of cephalonotum, mesoscutellum and hemielytra, wide mesoscutellum, ventral medial carina on abdominal sternum 6 that is absent in other Mixotrephes species , unmodified aedeagus, hook-shaped, densely hirsute apex of the left paramere, and unmodified subgenital plate of female (for comparison with characters of congeners see Tab. 1).

Etymology. The specific epithet pictus means painted and refers to the spotted pattern of the female’s hemielytra; adjective.

Habitat ( Figs 7, 8 ).This species was sampled in minute puddles on rock surface in the ‘spray zone’ of a waterfall. Small water beetles Microdytes sp. (Dytiscidae) and Laccobius (Glyptolaccobius) sp. ( Hydrophilidae ) (Jiří Hájek, pers. comm.) were also present in the collected samples. It is assumed that this species is part of a complex zoocoenose inhabiting petrolimnic to hygropetric zones of banks along fast streams with rapids and waterfalls.

Distribution. Only known from the type locality in the Bolaven Plateau, southern Laos.

Figures

Figs. 1–6. Mixotrephes (Pictotrephes) pictus sp. nov. 1–3 – holotype (male), 4–6 – paratype (female). 1, 4 – frontal; 2, 5 – dorsal; 3, 6 – lateral view. In Fig. 6, base of hemielytron not in normal position, covering posterolateral corner of cephalonotum. © NHMW Hemiptera Image Collection.

Figs.9–16. Structural characters of Mixotrephes (Pictotrephes) pictus sp. nov. (9, 11–16) and Mixotrephes hoberlandti Papáček, Štys & Tonner, 1989 (10). 9, 10 – outlines of cephalonotum and mesoscutellum from dorsal view (except M. (P.) pictus sp. nov., all other known Mixotrephes species have the same basic shape of mesoscutellum as M. hoberlandti); 11 – phallosoma; 12 – left paramere; 13 – right paramere; 14 – male abdominal sternum 8; 15 – female subgenital plate; 16 – first right valvula from ventral view. Scale bars: A = 1.0 mm (Figs. 9, 10), B = 0.2 mm (Figs. 14, 15), B = 0.1 mm (Figs. 11–13, 16).

Figs. 7–8. Type locality of Mixotrephes (Pictotrephes) pictus sp. nov., Laos, Champasak Prov., Bolaven Plateau, Tad Yueang waterfall. 7 – general view on the Tad Yueang waterfall; 8 – micro- habitat of the species – shallow puddles on rocky bank in the ‘spray zone’ of a waterfall. Photographs by Jiří Hájek.