Pleciogonus narumonae, Zettel & Laciny & T, 2021

Zettel, Herbert, Laciny, Alice & T, South, 2021, A second species of Pleciogonus (Hemiptera, Heteroptera, Gerridae) from Thailand, Linzer biologische Beiträge 53 (1), pp. 445-449 : 446-448

Pleciogonus narumonae nov.sp. ( Figs 1-3 )

H o l o t y p e (apterous female; Natural History Museum Vienna): Thailand, Phang Nga Province, Khuraburi District, Baan Tumnang, West of Si Phang Nga National Park , 29.XI.2006, leg. H. Zettel (#48) .

D e s c r i p t i o n: Measurements: Body length 5.60, maximum width (at mesopleura) 2.11. Head length 0.71, width (including eyes) 1.06; minimum distance of eyes 0.43. Pronotum length 0.63, width 1.21. Mesonotum length (at midline) 1.87. Metanotum length (at midline) 0.70. Combined length of abdominal tergites 1-7, 1.70. Length of antennomeres 1-4: 2.38, 0.64, 0.96, 0.64. Lengths of leg joints: Profemur 2.52, protibia 1.91, protarsus 0.90 + 0.71, mesofemur 7.58, mesotibia 1.82, mesotarsus 0.13 + 0.14, metafemur 7.42, metatibia 1.02, metatarsus 0.33.

Colour: Dorsal pattern as in Figure 1 . Sides yellow to pale orange. Venter pale yellow. Antennae black. Legs: coxae and trochanters chiefly yellow; profemur chiefly black; mesofemur black except extreme base yellow; metafemur, and all tibiae and tarsi black.

Structures: Head anteriorly only slightly protruded, antennal tubercles rounded. Antennomere 1 hardly longer than antennomeres 2-4 combined; antennomere 3 longer than each, antennomere 2 and 4. Pronotum transverse; sides rounded. Meso- and metanotum without special structures; hind margin of metanotum deeply sinuated. Profemur hardly incrassate, flexor side in distal half with numerous short black oblique spines; protarsomere 1 much longer than 2. Meso- and metafemur subequal in length, each longer than body. Mesotarsomeres subequal in length; metatarsomeres fused. Claws of middle and hindlegs reduced. Abdomen short. Mediotergites 1-6 transverse; 1 about 1.5 times longer than 2; 6 slightly shorter than 4 and 5 combined. Mediotergite 7 ( Fig. 2 ) about as long as wide; anterior two-fifths flat, posterior third folded in a roof-like shape; hind margin with two roundish convexities separated by a deep incision. Laterotergites steep; connexival margin strongly sinuate in dorsal view. Laterotergite 6 ( Figs. 2, 3 ) with a short, triangular protrusion. Sternum 7 as characteristic for the genus: sides posteriorly curved towards middle, posterodorsally broadly rounded; middle with a large lobe that is wider than hind margin of mediotergite 7. Segment 8 and genitalia retracted into segment 7.

C o m p a r a t i v e n o t e s: Pleciogonus narumonae nov.sp. can be easily distinguished from P. wongsirii by the structure of connexivum 6 of the female. In P. wongsirii it is posteriorly protracted in a long, slender, hirsute process that almost reaches or even surpasses the hind margin of tergite 7 (cf. CHEN et al. 2002: figs. 28, 30), whereas in P. narumonae nov.sp. it forms a short, inconspicuous, slightly acute angle, that has the length of one fourth of tergite 7 and does not bear any longer setae ( Fig. 3 ). A distinct spot of golden brownish pilosity at the middle of the mesonotal hind margin of P. wongsirii is lacking in P. narumonae nov.sp. Antennomere 1 is relatively shorter (compared to antennomeres 2-4) in P. narumonae nov.sp. than in P. wongsirii . The black areas of P. narumonae nov.sp. are comparatively more widely extended, especially on the profemur, but the pattern of P. wongsirii shows some variation in colour. We could not find differences in the genus-specific structures of abdominal segment 7.

E t y m o l o g y: This new species is dedicated to Associate Professor Dr. Narumon Sangpradub of the Khon Kaen University for her work on aquatic insects of Thailand.

Figures

Fig. 1: Pleciogonus narumonae nov.sp., habitus of apterous female (holotype). © Alice Laciny / Natural History Museum Vienna, Hemiptera Image Collection.

Figs 2-3: Pleciogonus narumonae nov.sp., apterous female (holotype): posterior part of abdomen, (2) in dorsal view (between bases of hind legs), (3) in lateral view; lt6 – laterotergite 6; mfe – metafemur; mt6, mt7 – mediotergites 6-7; mtr – metatrochanter; pr – process of laterotergite 6; st4- st7 – sterna 4-7.