Neoelmis guarani, Shepard & Barr, 2016

Shepard, William D. & Barr, Cheryl B., 2016, Neoelmis guarani Shepard & Barr, a sexually dimorphic new species from Paraguay (Insecta: Coleoptera: Elmidae: Elminae), Zootaxa 4083 (3), pp. 418-430 : 419-429

Neoelmis guarani sp. n.

Figs. 1–12

Holotype, adult male. Body slender, 2.1 mm long (pronotum + elytra), 0.7 mm wide at widest point; body color testaceous, appendages (antennae, palpi, legs) paler ( Figs. 1–5 ).

Head with frons moderately setose, setae long and pale; genae covered with fine, adpressed, plastron setae; eyes large, protuberant; antennal ridges produced, especially anteriorly. Antennae filiform, each with 11 segments; antennomeres 1–2 twice as long as wide, antennomeres 3–10 more than twice as long as wide; antennomere 11 clavate, slightly curved, longer than antennomeres 9+10 ( Figs. 1 , 2 ). Clypeus setose, transverse, apex feebly emarginate. Labrum transverse, apex arcuate; surface shiny with few setae; apicolateral margins with fringe of pale, dense setae. Maxillary and labial palpi each with three palpomeres.

Pronotum ( Fig. 1 ) elongate, 0.6 mm long, 0.5 mm wide at widest point about 1/3 distance from base; surface shiny, smooth, and sparsely clothed with pale, recumbent setae except for central disc where finely granulate and more densely setose; lateral margins bisinuate and irregularly crenulate; apicolateral angles acute, produced; posterior border bisinuate, notched medially to receive scutellum; prominent, wide transverse sulcus at 1/3 distance from apex, deeper fovea at midline with longitudinal groove which tapers posteriorly; two prominent, sinuate, sublateral carinae; broad, shallow depression between each sublateral carina and lateral margin, with a large fovea ventrally adjacent to transverse sulcus. Hypomeron with shallow depression on each side at basal 1/3 and a large fovea ventrally adjacent to fovea between lateral margin and sublateral carina; without plastron setae.

Scutellum subovoid, longer than wide, feebly convex.

Elytra ( Fig. 1 ) elongate, 1.5 mm long, 0.7 mm wide at widest point 1/3–1/2 distance from elytral apices; shallow linear punctures and setae present. Each elytron with a short, prominent, basal carina on third interval separating shallow lateral and medial depressions; two long sublateral carinae extending posteriorly from humeral angle, inner one extending to apical 1/3, outer one extending nearly to apex. Epipleuron with plastron setae, notched just before apex to receive tooth from abdominal ventrite 5.

Prosternum ( Fig. 2 ) longer than wide, with flat, evenly and lightly setose, shiny disc bordered by two longitudinal carinae 3/4 length of prosternum, fading out anteriorly; episternum clothed with plastron setae; prosternal process wide, apex extending posterior to procoxae, margins raised and rimmed with narrow sulcus between. Mesoventrite ( Fig. 2 ) shorter than wide; with a pair of large, posterolateral, ventrally projecting processes ( Fig. 2 , arrow) adjacent to and extending below mesocoxae; processes with ventromedially oriented, flattened surfaces; area between processes excavated; mesanepisternum with plastron setae. Metaventrite ( Fig. 2 ) shorter than prosternum, longer than mesosternum; disc flat, shiny, sparsely setose, with distinct discrimen; with two sublateral carinae extending from mesocoxae to metacoxae and small, carinate tubercle near each posterolateral margin; plastron setae present laterad to carinae and on metanepisternum. Pro- and mesocoxae globular; metacoxae transverse. Pro- and mesotrochanters of similar size, metatrochanters larger.

Prothoracic leg ( Figs. 1–4 ) with profemur abruptly and deeply excavated on both anterior and posterior surfaces 1/3 distance from apex ( Fig. 3 ), excavations lined with short, stiff setae ( Fig. 4 ); anterior surface bearing a large, blunt, distally directed tooth at inner edge of excavation; plastron setae present except in excavations. Protibia ( Fig. 4 ) slender, wider apically; posterior face with long setae present basally and apically and a deep excavation near apex; cleaning fringe of long, dense, pale setae on anterior surface. Protarsus ( Fig. 4 ) shiny, tarsomeres 1–4 with long setae ventrally, tarsomere 5 with a pair of long, projecting setae at apex; tarsomere 5 longer than tarsomeres 1–4 combined; claws simple. Mesothoracic leg ( Figs. 1 , 2 , 5 ) with mesofemur ( Fig. 5 ) widened medially; a deep, longitudinal groove present on ventral surface to receive tibia when folded, posterior margin of groove with numerous, long, curved setae; plastron setae present except inside of groove. Mesotibia ( Fig. 5 ) in lateral view with ventrally directed expansion at middle and shallow excavation on anterior face about 1/ 3 distance from apex; with anterior and posterior cleaning fringes ( Fig. 1 ) having long, tuft-like setae that extend beyond tibial apex. Mesotarsus similar to protarsus; right mesotarsus missing tarsomeres 3–5 due to breakage. Metathoracic leg ( Figs. 1 , 2 ) with metafemur unmodified. Metatibia with cleaning fringe on posterior surface at central 1/3; inner surface flat at apical 1/4, glabrous and shiny with a small peg near ventral margin. Metatarsus similar to pro- and mesotarsus.

Abdomen ( Fig. 2 ) with five ventrites; ventrites 1–4 decreasing in length posteriorly, ventrite 5 longer than all but ventrite 1. Ventrite 1 longest, with basomedial depression bordered by two short carinae which extend from posterior margin of metacoxae nearly to posterior margin of ventrite; surface shiny and sparsely setose between carinae, plastron setae present laterad to carinae. Ventrite 2 with a pair of processes ( Fig. 2 , arrow) projecting ventrally from anteromedial border, size of each process less than half that of each mesoventral process; surface between processes shiny, plastron setae present elsewhere. Ventrites 3–5 covered with plastron setae; ventrite 5 with a dorsally projecting tooth on each lateral margin which serves to link with a notch in the epipleuron. Ventrite 5 removed from abdomen and mounted on a card point.

Aedeagus ( Fig. 6 ) in dorsal view with phallobase twice as long as parameres, widely open in basal half; parameres widely open at apical 2/3 exposing penis; penis stout, sides faintly arcuate at basal 1/2, then moderately constricted and nearly parallel-sided to apical 1/8, thereafter evenly converging to narrowly rounded apex which extends slightly past paramere apices. Penis in ventral view with fibula at middle. Aedeagus in lateral view with apices of parameres and penis acutely pointed. Aedeagus removed from abdomen and placed in genitalia vial.

Allotype, adult female. Body slender, 2.3 mm long (pronotum + elytra), 0.8 mm wide at widest point about 1/ 3 distance from elytral apices ( Fig. 7 ). Slightly larger but generally similar to male except as follows: Each elytron ( Figs. 7 , 8 ) with a dorsally projecting protuberance in the third interval at about 1/3 distance from apex ( Fig. 7 , arrow), pointed and subtriangular in lateral view ( Fig. 8 ). Mesoventrite and abdominal ventrite 2 lacking modifications. All legs ( Figs. 7 , 8 ) without special modifications, similar to each other; tibiae with cleaning fringes. Ovipositor very elongate; valvifers more than 10 times longer than wide, thin basally then widest apically by coxites; coxites twice as long as wide, rectangular; styli 2-segmented, second segment very short.

Variation. Although seven specimens (three males and four females) is a small sample with which to examine variation, some differences were noted. Most striking of these are the different external modifications of males and females, detailed in the descriptions and Diagnosis. In addition, the females (2.2–2.3 mm long, 0.7–0.8 mm wide) are slightly larger than the males (2.1–2.2 mm long, 0.7 mm wide). In some specimens mineral deposits on the dorsum obscure details of the surface, causing semi-glabrous, shiny areas to appear granulate. Specimens also exhibit varying degrees of surface abrasion which can lessen the number of setae present in the abraded area compared to that of an unabraded specimen.

Diagnosis. The distinctive secondary sexual characters of N. guarani , present in both males and females, serve to distinguish this species from all other known species of Neoelmis . Males ( Figs. 1–5 ) have strong modifications of the profemora, protibiae, mesofemora, mesotibiae, and metatibiae, and bear a pair of ventral processes on both the mesoventrite and second abdominal ventrite. Females ( Figs. 7 , 8 ) have a dorsal pair of elytral protuberances and unmodified legs.

The aedeagus of N. guarani most closely resembles that of N. simoni (Grouvelle) which is known only from Venezuela ( Hinton 1939). However, in N. guarani the phallobase is open only in the basal half and the penis barely projects beyond the tips of the parameres, whereas in N. simoni the phallobase is open entirely and the penis projects well beyond the tips of the parameres. The aedeagus of N. guarani bears no resemblance to those of N. maculata , N. nelo , nor N. opis , other species occurring in Paraguay ( Hinton 1940a, 1972).

Type material. Holotype (male): PARAGUAY: Paraguarí [Dpto.], Arroyo Naranjo at Balneario Salto Cristal 7.5 km S Piribebuy , 17 Feb. 2011, C. B. Barr // 25º32.026’ S 57º01.717’ W; elevation 214 m // HOLOTYPE Neoelmis guarani Shepard & Barr [red label, handwritten]. Deposited in EMEC. A llotype (female): PARAGUAY: Cordillera [Dpto.], Piribebuy-Barrio Santa Ana, unnamed stream, 820 ft [250 m], 25º27.95’S 57º01.99’W, 18 VI 2006, [WDS-A-1687, on underside of label] // W. D. Shepard, leg. // ALLOTYPE Neoelmis guarani Shepard & Barr

[red label, handwritten]. Deposited in EMEC. Paratypes (2MM, 3 FF): PARAGUAY: Cordillera [Dpto.], Piribebuy-Barrio Santa Ana, unnamed stream, 820 ft [250 m], 25º27.95’S 57º01.99’W, 18 VI 2006 [WDS-A-1687, on underside of label] // W. D. Shepard, leg. // PARATYPE Neoelmis guarani Shepard & Barr [yellow label] (1M, EMEC); Cordillera [Dpto.], Piribebuy–B. Sta. Ana, 17 II 2011, 230 m, Arroyo Mborebi, S25º28.075’ W57º02.330’ // W. D. Shepard, leg. [WDS-A- 1830, on underside of label] // PARATYPE Neoelmis guarani Shepard & Barr [yellow label] (1M, INBP); Paraguarí [Dpto.], Arroyo Naranjo at Balneario Salto Cristal 7.5 km S Piribebuy, 17 Feb. 2011, C.B. Barr // 25º32.026’ S 57º01.717’ W, elevation 214 m // PARATYPE Neoelmis guarani Shepard & Barr [yellow label] (2 FF; EMEC, INBP); Paraguari [Dpto.], 15.3 km NE Paraguari, 18 II 2011, 282 m, Capilla Cue, S25º33.210’ W57º02.829’ // W. D. Shepard, leg. [WDS-A-1834, on underside of label] // PARATYPE Neoelmis guarani Shepard & Barr [yellow label] (1F, EMEC).

Etymology. Guarani, a noun in apposition, was chosen to honor the indigenous Guaraní people who are native to the region and whose language is widely spoken in Paraguay.

Distribution. Neoelmis guarani is known from four localities in the highlands area of the Cordillera de los Altos southeast of Asunción in the departments of Cordillera and Paraguarí. Although 42 streams have been sampled during our survey of the aquatic Byrrhoidea of Paraguay, the species has been found only in this small area. The elevations at the collection sites range from 214–282 masl and they are all less than 10 km apart (straight line distance) near the towns of Piribebuy and Chololó.

Habitat. The type locality, Arroyo Naranjo ( Figs. 9 , 10 ), is a small to medium-sized stream with slightly turbid water and a substrate of orange sand with sparse gravel/cobbles, numerous bedrock outcrops and ledges, and small waterfalls. The three other streams are similar in size and substrate, except that Arroyo Mborebí ( Fig. 11 ) lacks extensive bedrock outcrops, at least at the collection site ( Figs. 11 , 12 ). Other elmids collected in association with N. guarani include Heterelmis sp., Hexacylloepus sp., Hexanchorus sp., Macrelmis sp., Microcylloepus longipes (Grouvelle) , M. inaequalis (Sharp) , Neoelmis nelo Hinton , Phanocerus sp., Stenhelmoides sp., and Xenelmis micros (Grouvelle) .

Figures

FIGURE 1. Neoelmis guarani, male dorsal habitus; length 2.1 mm.

FIGURE 2. Neoelmis guarani, male ventral habitus; length 2.2 mm. Arrows indicate paired processes on the mesothorax and abdominal ventrite 2.

FIGURES 3 – 5. Neoelmis guarani, male. 3. Left prothoracic leg, femur, dorsal view. 4. Left prothoracic leg, posteroventral view. 5. Left mesothoracic leg, anteroventral view.

FIGURE 6. Neoelmis guarani, aedeagus, A—dorsal view, B—lateral view. Scale bar = 0.1 mm.

FIGURE 7. Neoelmis guarani, female dorsal habitus; length 2.3 mm. Arrow indicates paired elytral protuberances.

FIGURE 8. Neoelmis guarani, female lateral habitus; length 2.3 mm.

FIGURE 9. Arroyo Naranjo, type locality of Neoelmis guarani.

FIGURE 10. Arroyo Naranjo, type locality of Neoelmis guarani.

FIGURE 11. Arroyo Mborebí, Neoelmis guarani collection site.

FIGURE 12. Capilla Cue, Neoelmis guarani collection site.