Monochorhynchus Muir 1917

Genus Monochorhynchus Muir, 1917 Monochorhynchus Muir, 1917: 217. Type species Monochorhynchus wahri Muir, 1917 (by original designation). Description HEAD AND THORAX. Head including eyes somewhat narrower than pronotum, conjunction of vertex and frons angular and not protruding in profile. Vertex nearly trapezoidal, width of base greater than length, about twice that of apex, anterior margin distinctly carinate and slightly convex medially, and posterior margin roundly emarginate, basal area depressed, rising to apex. Frons narrow, with lateral marginal carinae widened and slightly separated by fine median sulcus in basal half, but thin and begin to abruptly diverge distad at same level as anterior apical angles of eyes. Clypeus triangular, longer than frons, with two longitudinal lateral carinae and stouter median one. Rostrum robust and elongate, extending beyond coxae of hind legs, with apical segment short and greatly enlarged at apex, forming sucker-like pad. Eyes reniform, with ventral margins obviously concave inwards, anteroventral angle protruding to near middle of frons; ocelli present. Antenna about half length of frons, pedicel cylindrical and truncated apically, with dense sensilla, flagellum terminal. Pronotum extremely short at middle, anterior margin obtusely convex, and posterior margin deeply concave, lateral parts expand to patagium-like, with dense tubercles. Mesonotum developed and diamond-shaped, with longitudinal median carina and two lateral ones, disc raised, often with tubercles along carinae, scutellum nearly trapezoidal. Tegmina elongate, about 3.5– 3.7 × as long as widest portion, narrowest basally and widest centrally, then slightly constricted distad, posterior margin arched, costal margin relatively straight with sensory pits in basal half, jugal margin slightly protruding, apical margin slightly emarginate. Costal veinlets (hm) connecting ScP+R (1) and ScP+RA (4) to costal margin; ScP+RA separating from RP before basal third of tegmina and slightly distad of CuA forking; RA 2 with two terminal branches; RP with four terminal branches, RP 1 sinuate; MP with nine terminal branches, MP 3+4 forked in single MP 3 and MP 4, MP 2 single, MP 1b two-branched, MP 1a four-branched, six veinlets connect every two branches of MP from MP 3 to MP 1aaa (not including between branches of MP 1b); CuA forked before first m-cu, CuA 1 and CuA 2 fused near apex to form a common stem and extending to posterior margin, C5 present; Pcu connected with A 1 at basal third of clavus; clavus open, narrow, and elongate, expanded apically. Tegminal markings scattered and veins mottled. Wings slightly shorter than half of tegmina and narrowly round at apex, with anterior margin slightly convex at middle; ScP+RA separating from RP before middle, MP with two branches, CuA with two branches, CuP, Pcu, and A 1 relatively short and straight, stridulatory plate present with convex outer margin. Metatibiotarsal formula: 5-(7–8)-6. MALE GENITALIA. Anal tube nearly triangular or trapezoidal in dorsal view, with lateral margins gradually converging distad, anal stylus located about middle, epiproct subrectangular, paraprocts elongate and cylindrical, extending to or beyond apex of anal tube, with few setae at apex; in lateral view, more than apical half part inclined ventrad, with slight dorsal process before turning point. Pygofer with laterodorsal angles round and not protruding, medioventral process present. Gonostylus short and broad, posterior part subquadrate, apex wider than base, dorsal margin thinly membranous, with auricular process at subapical part, dorsal apical angle acute and upcurved, apical margin medially protruding inwards; anterior part of gonostylus as long as posterior part, slender and clavate. Phallic complex broad and very complex, with various processes. FEMALE GENITALIA. One of highly reduced types of subtribe Lyddina Emeljanov, 1995. Anal tube (AT) highly modified into anal ring terminating in two styliform processes, dorsal epiproct, and ventral paraprocts clavate and extending caudad. Pygofer (segment VIII) annular, developed, and wellsclerotized, prominently expanded ventrally, with two spiracles (Sp) adjacent to anterolateral angles, surrounded by sclerotized plates. Medioventral plate (mvP) of segment VIII present. Intermedia plates (imP) paired and located dorsally to mvP. Anteroventral lip under oviporus following imP. Intergonocoxal plate IX (iGxP) more or less membranous. Gonocoxa IX developed. Gonoplac (Gp) laminated and C-shaped. Impaired mediodorsal sclerotized plate (mdP) connected ventrally to tergite IX. Remarks In the key provided by Fennah (1952), the genus is misplaced based on the following distinctions: 1) “Antennae generally longer than frons”; however, Muir’s (1917) illustrations showed that the antennae are distinctly shorter than the frons. 2) “Media generally with five sectors” and “first medial sector with two to four branches”; Muir’s (1917) descriptions stated, “Tegmina with six median sectors, the third furcate”, and further notes, “The tegmen in this genus is similar to that in Paraproutista (syn. Pamendanga Distant, 1906)”. This genus closely resembles Helcita Stål, 1856, and Formodanga Yang & Wu, 1994, but can be separated from them by the following features: 1) vertex with anterior margin distinctly carinate and slightly convex medially, whereas in Formodanga, vertex with anterior margin indistinctly carinate and distinctly incised medially; 2) head in profile not produced conically, whereas in Helcita, head in profile produced conically. In addition, sucker-like apical segment of rostrum, elongate paraprocts of males, and mottled tegminal veins (unknown in M. wahri) may be important features of this genus. The current research provides the first descriptions of female genitalia of this genus, and the reduced features support the classification of this genus under the subtribe Lyddina. The greatly enlarged apical segment of the rostrum easily distinguishes it from other genera within the subtribe (e.g., Proutista Kirkaldy, 1904 and Diostrombus Uhler, 1896) (Fig. 1B–D). Checklist of the species of Monochorhynchus Muir, 1917 1. Monochorhynchus dehongensis sp. nov. Distribution: China (Yunnan) 2. Monochorhynchus obscurus sp. nov. Distribution: China (Guangxi) 3. Monochorhynchus psammochroma sp. nov. Distribution: China (Fujian) 4. Monochorhynchus wahri Muir, 1917 Distribution: Borneo Key to the species of Monorhynchus Muir, 1917 (♂) 1. Anal tube with apex bifurcated in profile; pygofer with medioventral process truncated................... ................................................................................................................ M. psammochroma sp. nov. – Anal tube with apex single in profile; pygofer with medioventral process angular or round .......... 2 2. Body generally brownish; anal tube with apex curved caudad in profile .......... M. wahri Muir, 1917 – Body generally dark brown; anal tube with apex straight or inclined ventrad in profile ................. 3 3. Anal tube with apex round in dorsal view; pygofer with medioventral process round ...................... ...................................................................................................................... M. dehongensis sp. nov. – Anal tube with apex obtusely angular in dorsal view; pygofer with medioventral process obtusely angular ............................................................................................................... M. obscurus sp. nov.