Volesus nigripennis Champion, 1899, by monotypy.

Volesus can be separated from other genera of Sphaeridopinae by the combination of characters presented in the key below, and additionally by the following characteristics: eyes medium-sized, not covering the head; interocular distance larger than the width of eye, dorsally, and approximately equivalent to it, ventrally; labium with only two visible segments.

Body integument shiny, generally diffusely rugose, with linear irregular impressions more intensively and coarsely in thorax, except on lateral portions of mesosternum and median portions of some sternites, in which it is mostly smooth. Head subrectangular in dorsal view, moderately elongate in lateral view; transverse sulcus straight, moderately impressed meeting eyes at inner posterior angle; a midlongitudinal well-marked sulcus running from transverse sulcus to approximately level of anterior margin of eyes; antenniferous stout, cylindrical, diverging forward, straight apically; anteocular region curved downwards, not, or barely, visible in dorsal view; eyes medium-sized, interocular distance in dorsal view larger than width of an eye; labium with only two visible segments; first visible labial segment short, enlarged; second visible segment long, thin, straight. Thorax: pronotum trapezoidal; fore lobe much shorter and narrower than hind lobe of pronotum; transverse (interlobar) sulcus indistinct; median longitudinal sulcus ill defined, short, running on approximately basal fourth of hind lobe and separated from the median transverse depression of fore lobe by an irregular, curved carina. Prosternum somewhat depressed, with a pair of acute short, lateral processes, directed forward, median portion mostly occupied by stridulitrum, shortly prolonged posteriorly on midline, not surpassing the level of posterior margin of fore coxae and continuous with adjacent sclerite; meso- and metasternum flattened; fore coxae close, separate by a distance smaller than width of each coxa; middle and hind coxae separated from each other by a distance approximately equivalent to slightly more than twice width of each of them. Femora, tibia and tarsi slender, segments with similar width in all three pairs of legs; femora with a small ventral subapical protuberance; a small spongy fossa on apices of fore and mid tibiae. Tarsi three segmented. Abdomen enlarged at about middle portion; small scars of dorsal abdominal glands openings (dag) on medial anterior margins of tergites IV–VI; a vertical sclerite separating dorsal and ventral components of connexivum. Sternites with canaliculae (carinulate) on anterior margin of some segments.

Colombia, Costa Rica, Ecuador (new record), Panama (new record).

Volesus nigripennis was described based on a female from Costa Rica (Champion 1899). The female holotype is deposited at the Swedish Museum of Natural History (NRM), Stockholm, Sweden, and its photos are available on their website (Figs 1–3).

Forero (2004, 2006) recorded this species from Colombia, based on a unique female. These two females have been the only specimens of V. nigripennis known so far. Forero (2004) argued that the knowledge of the male of the species would be useful to a definition in relation to other members of Sphaeridopinae.

Additionally, a female specimen of V. nigripennis from Panama was located in the collection of the NMNH. Upon our request, Dr Silvia A. Justi (WRBU) examined the specimen, sent us photos of it and provided the data on the labels, which are transcribed below. The specimen was identified by the Late P. Wygodzinsky. Although it had been previously coated with metal for electronic microscopy, the identification of the specimen is still possible and represents a new record of this species for Panama.

Volesus nigripennis. ECUADOR, Esmeraldas, Tundaloma Lodge, near Calderón, 01.18277N, 078.75259W (01°10'57"N 78°45'09"W), 55m a.s.l., 8–9.ii.2014, A. Kury & A. Giupponi leg., 1 male (CEIOC), 1 male (CTJMSB).

Volesus nigripennis. PANAMA: Escobal Road / Atl. Canal Zone / 24 VI [19]74 [handwritten] / Col: D. Engleman // Drake Colln. ex / J. Maldonado C. / Coll 1996 [characters partially cut off at the bottom of the label] // Volesus [handwritten] / nigripennis [handwritten] / Champion [handwritten] / Wygodzinsky [det.], 1 female (NMNH).

Male. (Figs 4–57). Measurements: total length to tip of abdomen: 16.9–17.3; to tip of forewings: 16.1–16.5; head (excluding neck, measured in lateral view) length: 2.2; length of anteocular portion (measured in lateral view): 0.5; length of postocular portion (measured in lateral view): 0.7; width across eyes: 1.8; interocular distance, dorsal view: 0.9, ventral view: 0.5–0.6; width of eye, dorsal view: 0.5; ventral view: 0.6; length of eye: 0.6–0.7; distance between external margin of ocelli: 0.7–0.8; distance between ocelli: 0.25; maximum width of ocellus: 0.2–0.25; length of antennifer: 0.7; lengths of antennal segments: I: 2.5; II: 3.8; III: 1.5; IV: 0.9; lengths of labial segments, first visible: 0.3; second visible: 1.7–1.8. Thorax: pronotum: fore lobe, length: 0.8; maximum width: 3.2; hind lobe: length 3.0; maximum width: 5.9; scutellum, length: 2.3; width: 2.7; length of process: 1.1–1.2; length of hemelytra: 12.5. Fore legs: length of femur: 3.8; length of tibia: 4.8–4.7; length of spongy fossa: 0.25; length of tarsus: 1.2–1.3; middle legs, length of femur: 4.5–4.6; length of tibia: 4.8–5.1; length of spongy fossa: 0.25; length of tarsus: 1.2–1.3; hind legs: length of femur: 5.2–5.3; length of tibia: 6.3–6.7; length of tarsus: 1.3. Abdomen, length: 12.5; maximum width: 7.7–7.8.

Coloration: general coloration blackish with reddish markings (Figs 4–5, 14, 20, 26, 28, 35). Head generally blackish; neck mostly reddish; apices of antenniferous tubercles pale; antennal segment II brownish black; antennal segments III–IV brownish; labium brownish (Figs 4–6, 9–11, 14, 20). Thorax blackish, brownish black on meso- and metasternum, with the following reddish thoracic markings: on anterior collar and their projections; on lateral and posterior margins of pronotum; on most of fore lobe of pronotum, except its median portion; on hind lobe of pronotum, a median and a pair of lateral converging bands, which are continuous with reddish posterior margin, ending approximately at mid and anterior thirds of hind lobe, respectively; and on postero-superior portion (approximately) of propleura and process of scutellum (Figs 4–6, 14, 16, 20, 26, 28). Legs generally blackish; spongy fossa on fore and mid tibiae somewhat paler (Figs 4–5, 20, 24–25). Hemelytra black, somewhat paler, brownish, on approximately distal half of clavus, medially and about distal half of the membrane, except veins and area just surrounding them (Figs 4–5, 26). Hind wing generally brownish, with veins darkened (Fig. 27). Abdomen blackish to blackish brown; tergite VI with a median reddish spot just below anterior margin; tergite VII almost completely reddish, blackish on and just below anterior margin and with a pair of rounded blackish spots on mid-lateral portion (Fig. 28). Connexivum reddish on: extreme base of segment II, approximately basal third of segments III–V, and somewhat less than basal half of segment VI; connexival portion of segment VII almost entirely reddish with only posterior border of approximately distal half darkened; ventrally, marking on segment II is a small spot on external margin; on segments III–VI connexival reddish markings are prolonged dorsally to a short distance on lateral portion of respective tergite as a subtriangular marking, and ventrally, as a somewhat curved lateral marking, directed backwards, reaching spiracles, which are surrounded by reddish posterior margin; sternite II with anterior margin and median portion, on approximately distal half reddish to reddish brown; transverse median bands, on sternites III–VII, progressively larger, reddish brown in one specimen and pale brownish in other, joining lateral reddish markings described above in sternites V–VII, the latter almost completely reddish, with dark coloration restricted to anterior margin and adjacent to genital capsule (Figs 4–5, 26, 28, 35). Exposed portion of pygophore and parameres blackish (Fig. 35).

Vestiture: body generally covered by sparse short, somewhat curved, adpressed, thin, golden to brownish setae. Head: eyes, ocelli and neck glabrous; region adjacent to insertion of labium with more numerous and somewhat longer setae; ventral surface of first visible labial segment and basal portion of second visible labial segment moderately setose, dorsal surface of correspondent portions with fewer setae; additionally, some sparse setae scattered on the proximal third of second visible segment, remainder glabrous. Antenna: segment I sparsely covered with setae similar to those of general vestiture but slightly longer, more numerous at apex; segments II–IV densely setose, covered with scattered longer, somewhat curved, brownish setae and much more numerous shorter, thinner, whitish setae (Figs 9, 10). Thorax. Some longer straight thin setae on posterior margin of pronotum adjacent to lateral portion of scutellar base; setae are sparser on ventral surface; smooth lateral areas of mesosternum glabrous. Hemelytra: small adpressed setae sparsely scattered on corium, more numerous at its apex; apical two thirds of clavus, respective adjacent area of corium and membrane glabrous. Legs generally with similar vestiture of the body; setae longer and thicker on tibiae, becoming more numerous towards apex; tarsi with stiff, pale, yellowish to golden-yellowish, oblique to curved setae, with variable lengths. Abdomen: tergites I–V almost completely glabrous, with some scattered small darkened or pale setae, almost imperceptible; tergite VI with some more numerous pale setae; tergite VII with scattered longer golden setae. Connexivum: lateral margins with numerous adpressed short curved darkened setae, forming a few irregular rows; these setae become somewhat longer and paler on distal margin of segment VII; segments II–VI dorsally glabrous; some sparse setae on dorsal surface of distal third of segment VII. Sternites generally covered with sparse thin golden to pale setae; somewhat longer and more numerous setae on median portion of segments VI–VII and on pygophore, except its middle portion.

Structure: Head. Anteocular portion slightly shorter than postocular portion (in lateral view); ocelli separated by a distance slightly larger than transverse width of each ocellus, positioned medially to level of inner posterior angle of eyes and close to transverse sulcus; antenniferous large; first antennal segment slightly longer than head, stout, somewhat curved, its approximately basal fourth slightly thinner; remaining antennal segments progressively thinner, cylindrical; labium reaching or surpassing the mid third of stridulitrum (Figs 6–14, 20–22). Thorax. Anterior collar inconspicuous; anterolateral angles rounded and small (Figs 15, 16); fore lobe with irregular areas with smooth and whitish integument; a median transverse depression on fore lobe present between medial margins of longer curved smooth areas (Figs 14–17); humeral angles acute, slightly prominent (Figs 14, 18); posterior margin of hind lobe slightly curved on middle third (Figs 14, 15). Scutellum sculptured, median depression shallow, process stout, horizontal, apex rounded (Figs 14, 19). Distance between acute prosternal processes: 0.7. Hemelytra generally dull; on extreme base of dorsal surface, laterally, and on lateral portion, basally, moderately shiny; not reaching tip of abdomen, ending somewhat apically to level of the mid third of seventh tergite (Figs 4–5, 26); in one specimen, the membrane has a small additional cell at approximately apical fourth of cubital vein (Fig. 26). Abdomen. Integument generally also rugose (Figs 28–34), except on median portions of sternites IV–VII, in which it is mostly smooth (Figs 34–38). Connexivum largely exposed, laterally to hemelytra (Figs 4–5); anterior margin of tergite I carinulate (Figs 29–31); tergite II with a mid-longitudinal keel and median third of posterior margin curved backwards (Figs 28–31). Sternites carinulate on anterior margin of segments III–V in one specimen and also on segment VI in the other; on sternite III, canaliculae are somewhat larger and extend more towards lateral portion, occupying approximately two thirds of anterior margin, except midline; on following segments canaliculae become progressively slightly smaller and occupy approximately median third of anterior margin, except midline; a median shallow keel on distal two thirds of segment II and somewhat more elevated in sternites III–VI (Figs 35–38). Segment VIII not visible externally, sclerotized on ventral portion, which becomes somewhat wider towards posterior margin; latter almost straight and with a few short setae; dorsal portion membranous and narrower; spiracles on dorsal margin of ventral portion (Figs 39–41).

Male genitalia (Figs 35, 39–40, 42–57): genital capsule, in ventral and lateral views: exposed portion of pygophore hemispherical, posterior margin (pm) flattened, integument rugose and setose; non-exposed portion of pygophore less pigmented and less sclerotized, integument smooth and glabrous (Figs 39, 42–44); in dorsal view: between anterior and posterior genital openings, a very well-sclerotized dorsal (transverse) somewhat curved bridge; socket of insertion of paramere (sp) approximately in mid portion of pygophore, with a conspicuous medial prolongation obliquely directed posteriorly (psp); numerous, somewhat long, erect setae inserted on inner surface of basal portion of this prolongation; membranous areas of genital opening smooth; proctiger (pct) somewhat enlarged toward apex, with numerous long setae on distal half; posterior dorsal margin of pygophore (pdm) large, forming a horizontal extension of pygophore wall, with some scattered setae on inner margin and more numerous and somewhat shorter elements on median portion (Fig. 40). Median process of pygophore (mpp) only visible in dorsal and lateral views of pygophore, directed upwards, situated some distance from posterior margin, somewhat enlarged, almost straight and subsquared in dorsal and anterior views, respectively (Figs 40, 42–43, 47). Paramere apices in contact in resting position (Fig. 35); parameres (pa) (Figs 40, 42–43) symmetrical, elongated, with a lateral rounded enlargement just above inserted portion, moderately and strongly curved inwards at mid and apical portions, respectively, narrowing towards tip, which is somewhat rounded (Fig. 45) to acute (Fig. 46); with straight to moderately curved setae, more numerous towards apical portion; setae absent on basal (inserted) portion and on inner surface of approximately basal fourth of the not inserted portion (Figs 40, 43, 45–46). Articulatory apparatus with moderately short basal plate arms (bpa); basal arms and basal plate bridge (bpb) forming a subtriangular set (Fig. 50); basal plate bridge (bpb) slightly bent ventrally (Fig. 50); pedicel (pd) elongated, somewhat enlarged at midportion, curved in lateral view (Figs 48, 49, 51, 52). Before inflation of the endosoma, a lateral oval area (loa) somewhat more sclerotized on endosoma wall is evident (Figs 48–50) as well as a conspicuous dorsal pair of membranous lobes on endosoma (mle), united at their basal median portion which is inserted just above apex of dorsal phallothecal sclerite (dps) (Fig. 50). Each membranous lobe on endosoma (mle) is flattened, elongated, apex rounded, directed outwards, laterally to dorsal phallothecal sclerite (Figs 48, 50–52, 55). Dorsal phallothecal sclerite (dps) elongated, thrice curved in lateral view (Figs 51, 54); in dorsal view, it is narrower at approximately midportion and towards apical portion (Fig. 53); apical margin almost straight (Figs 50, 52, 53, 56); at its subapical enlarged portion there is a pair of symmetrical rounded flat lateral expansions (fle) (Figs 50, 52, 53). After inflation of endosoma, endosoma wall is smooth to longitudinally and transversely finely striated at approximately basal two thirds and coarsely rugose at distal third, with some areas in which the rugosities are more sclerotized (ars) (Figs 56, 57); endosoma wall forming three apical expansions: a median subrounded flat expansion (mfe) and a pair of lateral tubular short expansions (lte), each of the latter with a more sclerotized thin longitudinal line along its length (lsl) (Figs 52, 57). Endosoma with the following processes: a pair of flat, somewhat sclerotized, asymmetrical and striated processes (stp) between apex of dorsal phallothecal sclerite and subapical process (sbp) (Fig. 56). The subapical process (sbp) provided with a pair of sclerotized arms, in which basal halves are shorter, diverge more and are formed by stronger sclerotizations of rugosities of wall, while distal half is somewhat longer, less diverging and formed by linear and aggregate thickenings (Figs 51, 52, 56, 57).

Colombia, Costa Rica, Ecuador (new record), Panama (new record).

Volesus nigripennis is the first Sphaeridopinae recorded for Ecuador and Panama (Froeschner 1981, 1999, Maldonado 1990).

The male specimens (Figs 4, 5, 20, 35) described here seem to be generally similar to the female of the species in structure and coloration (Champion 1899, Forero 2006; Figs 1, 2). However, only the examination of more specimens of V. nigripennis will make it possible to ascertain whether there is sexual dimorphism.

Smooth areas on the fore lobe of pronotum were recorded here in V. nigripennis (Figs 6, 15–17) but it was not possible to distinguish a paired sensory organ similar to that described in Sphaeridops eulus by Maldonado and Santiago-Blay (1992: figs 13, 14). These authors emphasized that the nature of the sensory organ of these areas could be seen in their SEM images. However, judging by the SEM images obtained in the present study (Figs 15, 17), it is possible that the supposed sensory organ, also mentioned as present in both species of Veseris (Gil-Santana et al. 1999, Gil-Santana and Alencar 2001) may be in fact a portion of these smooth areas. Only future studies, preferably employing histological techniques will allow the evaluation of the existence and/or possible sensory functions of such portions in these species.

Although Champion (1899) had described that the labium would have the second and third visible labial segments equal in length, our studies, including the SEM images, made it clear that the labium is formed by only two visible segments, with the first visible segment short and enlarged and the other long, thin and straight (Figs 11, 12). It is opportune to mention that, according to our request, Dr Dimitri Forero kindly reexamined the female recorded by him from Colombia, sent us photos and confirmed these same features on the labial segments. Similarly, Dr Silvia A. Justi, when examining the female specimen from Panama, also verified that it had only two visible labial segments, with the same characteristics.

Some of the portions of the male genitalia of V. nigripennis, such as the parameres and articulatory apparatus, including a basal plate bridge bent ventrally (Figs 40, 45, 46, 50) seem similar to those recorded for species of Veseris (Gil-Santana et al. 1999, Gil-Santana and Alencar 2001).

Weirauch (2008) recorded the presence of the basal plate bridge (=ponticulus basilaris) bent ventrad and a pair of membranous lobes on endosoma, lateral to the dorsal phallothecal sclerite in Sphaeridops amoenus and Salyavata nigrofasciata Costa Lima, 1935 (Salyavatinae). Judging by her drawings, these lobes are smaller in S. amoenus and somewhat larger but shorter in S. nigrofasciata, respectively, than those recorded here in V. nigripennis (Figs 50–52). It is noteworthy that Weirauch (2008) considered both characteristics (a basal bridge bent ventrad and the pair or membranous lobes on the endosoma) as synamoporphies of the clade Salyavatinae + Sphaeridopinae obtained in her cladistic analysis.

On the other hand, because all other structures, such as those of phallus and endosoma, were not adequately recorded by the above-mentioned authors, nor by others who included just partial or incomplete descriptions of the male genitalia of species of Sphaeridops (e.g. Maldonado and Santiago-Blay 1992, Gil-Santana et al. 2000), only future comprehensive studies of these structures among Sphaeridopinae will allow useful comparisons with the results obtained here.