Megamelus serpentinus Mariani & Remes Lenicov, 2025

Megamelus serpentinus Mariani & Remes Lenicov sp. nov.

Figs 4 View Figure 4 , 5 View Figure 5 , 6 View Figure 6

Type material.

Holotype male (macropter): Argentina • Corrientes, Esquina , - 29.99197098266, - 59.52115137130, V- 2022, on Pontederia azurea, Salinas-Sosa col. ( MLP) . Paratypes • same data as holotype, 3 macropterous males (1 with genitalia dissected), 5 macropterous females, 2 brachypterous females, 2 brachypterous males ( MLP) .

Other material.

Argentina • 1 male macropter, Santa Fe, Reconquista , 26 - XI- 1939, Biraben-Bezzi ( MLP) ; • 1 female macropter, Chaco, Resistencia , 20 - III- 1939, Denier, col. ( MLP) ; • 1 female brachypter, Misiones, Concepción de la Sierra , 27 - XI- 2022, on Pontederia azurea, Salinas col. ( MLP) ; • 1 male brachypter, Buenos Aires, Arroyo Botija , 10 - VI- 2023, on Pontederia azurea, Salinas col. ( MLP) ; • 2 female macropters, Corrientes, Ramada Paso , 15 - V- 2022, on Pontederia azurea, Salinas col. ( MLP) ; • 2 female macropters, Corrientes, Bañado Virocay , 27 - XI- 2022, on Pontederia azurea, Salinas col. ( MLP); Paraguay : • 2 female macropters, Cordillera, Arroyos y Esteros , 7 - IV- 2022, on Pontederia azurea, Salinas col. ( MLP) .

Type locality.

Argentina, Corrientes: Esquina, - 29.9920 S, - 59.5212 W, on Pontederia azurea floating near the bank of a stream, 12 May 2022.

Diagnosis.

Macropter and brachypter. The salient features of the new species include the following: body mostly dark brown with distinctive yellowish to white marks bordering most of the sclerites of the body with legs paler and lightly marked with dark pigment. Macropters with forewings amber with pale brown veins, with strong dark marks on clavus, along Cu vein, over cross veins, and on last apical cells; brachypter with tegmen amber, brownish transverse marks in middle and claval apex, male pygofer dark brown, with dorsal surface, anal angles, and anal segment pale brown. Vertex narrow, with submedian carina forking dorsally quite far from fastigium; carinal branches closely forming a slender triangle; fastigium rounded in lateral view. Frons long, median carina prominent at or just below fastigium then fine; lateral carinae at base foliated, all carinae fine before the well-defined frontoclypeal suture. Spur large and wide, with 17 or 18 sharp, black-tipped teeth on trailing margin. Male terminalia: pygofer with relatively large lobes, the inner sharpened at apex with rounded external margin and internal sinuous; aedeagus short and tubular, with a short, slender dorso-caudally process curved at apex. Anal segment with two long, sinuous, slender caudally directed processes projecting laterally from the base.

Description.

Macropterous male (Figs 4 A – C, G View Figure 4 , 5 A – F View Figure 5 ). Color (Fig. 4 A – C View Figure 4 ) dark brown, with distinctive marginal castaneous and yellowish white marks on head, thorax, and abdomen. Head yellowish on posterior compartments of vertex and fovea, only infuscated in concavities, and on both sides of lateral and median carinae of face below fastigium; distinctive whitish marks below the eyes and across frontoclypeal area. Thorax, whitish colored on the pronotal disc between lateral carinae, one spot behind eyes on paranotal disc, a subtriangular shaped spot on each side of postero-lateral margin of mesonotum, metanotum, and scutellum; yellowish, on lateral edges of pronotum, tegula, and a suboval longitudinal median spot on mesonotum disc. Antennal segments pale castaneous with basal segment and proximal 1 / 2 of second segment darkish on dorsal surface. Legs yellow with tarsi dorsally darker, with longitudinal darker spots near base and apex of pro- and mesocoxae, on dorsal surface of femora, apical region of metafemur, and base and apex of metatibiae. Forewing amber, veins pale brown, fuscous along apical veins M 1 + 2 and M 3 + 4 with infuscate areas on central nodal line, last apical cell, along Cu vein, on postclaval angle, and apex of clavus. Abdomen in dorsal view with contrasting white yellowish coloration on drumming segments and two lateral spots on tergites V and VIII, ventrally with most of the segment margined with yellow. Pygofer dark brown on outer lobes and ventral surface; pale castaneous on dorsal surface and inner lobes. Anal segment yellowish and anal style dark brown (Fig. 4 A, B View Figure 4 ).

Structure. Head narrower than pronotum. Vertex rectangular, longer than wide at base (2.1: 1) projecting beyond eyes> 1 / 3 of its length, with rounded frontal inflection; basal compartment slightly concave, occupying approximately more than basal third, stem of Y-shaped carina fine, delimiting shallow depressed areas on both sides; other carinae of head pronounced; submedian carinae forking at dorsal surface of vertex, quite far from fastigium, carinal branches forming a slender triangle, fovea, or areola little> 2 × the length; median carina strongly ridged and prominent at base at or just below fastigium then smooth; lateral carinae foliated at base, removed from eye along the length. (Fig. 4 A View Figure 4 ). Frons nearly 3 × longer than wide (3: 1.1), strongly narrowed between anterior margins of eyes, maximum width near basal 1 / 3, lateral margins slightly convex at apex; lateral and submedian carinae fine just before frontoclypeal suture, which is arched dorsally. Clypeus subtriangular, longer than wide, median carina weaker at base. Eyes globose, deeply emarginate below to receive the antennae. Rostrum reaching metacoxae, longer than frons, subapical and apical segment subequal. Antennae with the first segment longer than wide, the second segment <2 × the first, length> 2 × its width (Fig. 4 A, B View Figure 4 ). Pronotum with conspicuous carinae, laterals divergent, slightly convex toward hind margin, reaching it. Mesonotum almost as long as vertex plus pronotum, fine median carina becoming obsolete at apex, lateral carinae inconspicuous, slightly divergent posteriorly, not reaching hind margin (Fig. 4 A View Figure 4 ). Forewings rather long and slender, rounded at apex, length 3 × their width at subapical region, surpassing distal end of abdomen> ~ 1 / 3 of their length. Metatibial spur, leaf-like, long, and broad, with median rib becoming obsolete at apex which is truncated without teeth, slightly longer than metatarsomere I, with 17 or 18 regular, large, black-tipped teeth on trailing margin; first hind tarsomere longer than second plus third (1.5: 1) (Fig. 4 G View Figure 4 ). Abdomen regularly wide, compressed dorsoventrally (Fig. 4 A View Figure 4 ).

Terminalia (Fig. 5 A – F View Figure 5 ). Pygofer in dorsal view, with deeply concave anal emargination, anal angles distinctly projected caudad. In ventral view, expanded, with large, round, kidney-shaped outer lobes enfolding almost the entire lateral surface (Fig. 5 A, B View Figure 5 ); inner lobes, large, wide in basal 2 / 3, external margin rounded, inner margin sinuous ending apically pointed with deep and broad concavity between their bases; strong emargination between inner and outer lobes (Fig. 5 A, B View Figure 5 ); diaphragm broad with dorsal margin deeply concave and medially caudad projected into lip-shaped process bearing bunch of rather short, stiff hairs. Aedeagus short, tubular, strongly narrow at base, widening up to the basal 1 / 3 then uniformly tubular and obliquely truncated at apex, with a single short, slender, apically curved process extending shortly beyond oval and apical phallotreme (Fig. 5 C, D View Figure 5 ). Genital styles (parameres) long, narrow, convergent apically, expanded and gradually tapering basally, broadly rounded along apical 1 / 2 on outer margin, apex hook-like, very curved inward; in ventral view visible between the internal lobes, in almost its entire length (Fig. 5 E View Figure 5 ). Suspensorium strap-like, connected to the aedeagal base, as long as half length of aedeagus (Fig. 5 C View Figure 5 ). Connective slightly compressed, almost straight (Fig. 5 C View Figure 5 ). Anal segment tubular, longer than twice the width, with caudal margin deeply emarginate ventrally; with two long, sinuous, slender, caudally directed processes arising ventrolaterally just below anterior angle which is membranous; anal style slender, twice longer than broad (Fig. 5 F View Figure 5 ).

Measurements (n = 6). L., 3.8; B. L., 2.3; b. w., 1; t. l., 3.2; v. l., 0.4; v. w., 0.2; f. l., 0.6; M. f. w., 0.3; m. f. w., 0.2; a. l. I, 0.15; a. l. II, 0.3; p. l., 0.2; m. l., 0.5; mti. l., 1.13; mta. l., 1; mta. Il., 0.7; s. l., 0.8; t. n., 17–18.

Brachypterous male. Color similar to macropterous form, with mesonotum paler and uniformly colored; tegmen amber with veins concolorous, with fuscous transverse marks continuous or fragmented, from base of clavus at near axillary region, and one spot at claval apex. Abdomen with similar patterns except tergites V and VI which are more uniformly dark brown contrasting with yellowish segments VII and VIII.

Structure. Mesonotum shorter,> 1 / 2 of vertex plus pronotum length. Tegmen slightly longer than wide, rounded on external lateral margins; posterior margin truncate, covering tergite II.

Measurements (n = 6). L., 2.3; b. w., 0.8; t. l., 1; v. l., 0.4; v. w., 0.18; f. l., 0.6; M. f. w., 0.25; m. f. w., 0.15; a. l. I, 0.15; a. l. II, 0.3; p. l., 0.2; m. l., 0.25; mti. l., 0.9; mta. l., 0.9; mta. Il., 0.6; s. l., 0.65; t. n., 17–18.

Macropterous female (Figs 4 E, F View Figure 4 , 5 G – I View Figure 5 ). Color: Head and thorax resemble male. Abdomen, in dorsal view, with contrasting yellowish marks on sides and posterior margins of sclerites, except V and VIII, which are uniformly brown. Abdominal sternites with yellowish margins; pygofer and anal segment yellowish, anal style castaneous; ovipositor dark brown (Fig. 4 E, F View Figure 4 ).

Structure. Resembling male but abdomen is sharply tapered towards genital segments. Forewings surpassing distal end of abdomen ~ 1 / 6 of their length. Anal segment subrectangular; anal style slender.

Terminalia (Fig. 5 G – I View Figure 5 ). Pygofer long, tubular-shaped, tapering toward the apical 1 / 2; in dorsal view exposed shortly beyond tergite VIII. Ovipositor long, strong, slightly sinuous in apical 1 / 2, as long as length of pygofer plus anal segment. Valvifer VIII regularly wide, inner margin rounded at base, separated in repose (Fig. 5 G View Figure 5 ). Gonapophysis IX, long and slender, overall shape slightly sinuous, apical fifth concave ventrally, with numerous blunt small teeth on most of dorsal surface (Fig. 5 H, I View Figure 5 ).

Measurements (n = 10). L., 4.3; B. L., 3.2; b. w: 0.9; t. l., 3.5; v. l., 0.45; v. w., 0.2; f. l., 0.7; M. f. w., 0.3; m. f. w., 0.2; a. l. I, 0.2; a. l. II, 0.3; p. l., 0.2; m. l., 0.6; mti. l., 1.1; mta. l., 1; mta. Il., 0.7; s. l., 0.6; t. n., 21–23.

Brachypterous female (Fig. 4 D View Figure 4 ). Color pattern similar to that of the macropterous female, but tegmina resemble those of brachypterous male.

Measurements (n = 5). B. L., 2.9; b. w: 0.8; t. l., 1; v. l., 0.45; v. w., 0.2; f. l., 0.7; M. f. w., 0.3; m. f. w., 0.2; a. l. I, 0.2; a. l. II, 0.3; p. l., 0.2; m. l., 0.3; mti. l., 1; mta. l, 1; mta. Il., 0.6; s. l., 0.7; t. n., 21–23.

Etymology.

The specific name comes from the Latin, serpentinum (serpentine), referring to the undulated shape of the long and slender male anal processes.

Distribution.

Argentina: Misiones, Chaco, Corrientes, Santa Fe, and Buenos Aires provinces. Paraguay: Cordillera department (Fig. 6 A View Figure 6 , Suppl. material 2).

Host plant.

Pontederia azurea Sw.

Ecology.

In the field, M. serpentinus was recorded on P. azurea in wetlands of the La Plata Basin (Fig. 6 B – D View Figure 6 ). Both adults and nymphs were observed feeding on the host plant.

Remarks.

This species is distinguished from the other South American Megamelus species principally by their characteristic coloration and the morphology of the male genitalia. Salient features include whitish yellow marks on head, thorax and abdomen, forewings with strongly dark marks on clavus, along Cu vein, over cross veins and last apical cells; the slender vertex with submedian carinae forking at dorsal surface, quite far from fastigium; male with inner lobes of the pygofer long and sharpened at apex with a strong emargination among inner and outer lobes; the aedeagus short and tubular with a short thin apical process slightly curved apically, and the long anal segment with a long, slender and sinuous, posteriorly directed anal processes, emerging from its anterior ventral margin.

Among its congeners, M. serpentinus shares morphological features with M. davisi such as the sinuous shape and placement of the anal processes in the male, the long ovipositor in the female and the large foliaceous spur, truncated at apex. The examination of the type specimens, macropter and brachypter, in the NHNM collection, by AMRL (Fig. 7 View Figure 7 ) showed that M. davisi has a darker coloration, almost piceous black with the carinae and fine edges on sides and posterior margin of pro and mesothorax pale, the forewings whitish with only claval area darkish, and the tegmina darker with pale veins (in the brachypter). Megamelus davisi also differs in the submedian carinae of vertex which is forked just on fastigium, and the flat shape of the aedeagus with a narrow twisted apex ( Beamer 1955: 32, plate 1, fig. 1). Megamelus serpentinus also shares with M. timehri and M. davisi the arrangement of the anal segment processes, caudally projected from the anterior ventral margin of the segment.