Rasahus abolitus, Swanson, 2018

Swanson, Daniel R., 2018, Three new species of Rasahus, with clarifications on the identities of three other Neotropical corsairs (Heteroptera: Reduviidae: Peiratinae), Zootaxa 4471 (3), pp. 446-472 : 455-458

Rasahus abolitus sp. nov.

( Figs. 3 , 10B , 11C )

Diagnosis: Easily separated from all other species of Rasahus by the combination of small size (male less than 12 mm) and the obsolete pronotal sulci and granules. The external genitalia of the male also are unique in possessing the combination of a strongly-bent, apically-tapering median process of the pygophore.

Coloration: Blackish, except apical spine of scutellum, apical interior of clavus from scutellar spine to apex, adjacent part of corium from base to apex of clavus, three spots on hemelytral membrane (ovoidal spot near base, narrow arcuate spot near apex of corium, and forked spot at apex), anterior half of connexiva (dorsally and ventrally, with adjacent part of ventrite), apex of coxae, base of metafemur, base of all tibiae, and meso- and metatarsi whitish. Incisures of antennal segments (plus, base of scape), protarsi, and fossula spongiosa brownish.

Structure: Anteocular region covered on all surfaces with short silvery pile, laterally with few long dark setae. Interocular region with width subequal to width of eye, with three setae in triangle and silvery pile dorsally (less so than anteocular but possibly abraided). Postocular region with short longitudinal sulcus reaching cephalad from transverse sulcus. Neck dorsally glabrous, laterally and ventrally with short pile.

Antennae: as per description under Rasahus .

Eyes in lateral view surpassing dorsal margin and nearly reaching ventral margin.

Ocelli large, somewhat raised, separated from each other by width of one ocellus, separated from eye by less than width of one ocellus.

Rostrum: as per description under Rasahus .

Pronotum: Anterior pronotal lobe with sulci essentially obliterated, short and long setae in remains of sulci, glabrous inbetween, disc unarmed, deep sulcus on midline in front of transverse suture that extends cephalad to middle of lobe. Posterior pronotal lobe smooth, without wrinkles or sulci, pilose along lateral and posterior margins.

Scutellum mostly obscured by pin, apex prolonged in dorsally-setose spine.

Pleura: Propleuron smooth. Metapleuron slightly transversely wrinkled, glabrous, metapleural sulcus narrow between carinae.

Sterna: Metasternum medially obscured by pin, possibly carinate midlongitudinally.

Hemelytra slightly but distinctly exceeding abdominal apex, veins of corium bearing semi-erect setae.

Forelegs: Profemur with ventral setae arranged in two rows. Protibial fossula spongiosa long, greater than halflength of tibia.

Middle legs: Tibia generally more pilose (more densely so ventrally) and with fewer distinct dorsal setae, mesotibial fossula spongiosa relatively shorter, about half-length of tibia. All else as fore legs.

Hind legs: as per description under Rasahus .

Abdomen connexiva with long thin seta at posterolateral angle, sutures poorly indicated. Apex of seventh ventrite strongly pilose.

Male genitalia: Eighth ventrite extended caudad as median triangular spine. Pygophore sparsely pilose, posterior margin concave between median process and base of parameres, median apical process tall, strongly sinuate (left margin strongly curved, right margin weakly so), broad and bent sinistral in basal half, curving dextral in apical half, apically tapering to acuminate point. Parameres large, asymmetrical, both spade-shaped, more pilose than pygophore, especially near apex, left paramere larger, with attenuated, mesally-bent, somewhat flattened apex, right paramere slightly broader with non-attenuated tectiform apex. Aedeagus not examined.

Female: unknown.

Measurements (in mm): total length (apex of head to apex of hemelytra): 10.2; head length: 1.7; head width (across eyes): 1.2; anteocular length: 0.7; postocular length: 0.3; neck length: 0.3; scape length: 0.8; pedicel length: 2.2; basiflagellum length: 1.8; distiflagellum length: 2.3; antennal segment ratio: 1.0: 2.75: 2.25: 2.9; eye length: 0.7; eye width: 0.4; rostral segment 1 length: 0.6; rostral segment 2 length: 1.0; rostral segment 3 length: 0.6; rostral segment ratio: 1.0: 1.67: 1.0; prothorax length: 2.4; prothorax width (across humeri): 2.5; anterior pronotal lobe length: 1.7; posterior pronotal lobe length: 0.7; scutellum length: 1.2; scutellum width (at base): 0.9; hemelytra length: 8.1; procoxa length: 1.6; protrochanter length: 0.6; profemur length: 2.7; protibia length: 2.5; protibial fossula spongiosa length: 2.0; protarsi length: 0.6; protarsal segment ratio: 1.0: 1.6: 1.6; mesocoxa length: 0.7; mesotrochanter length: 0.6; mesofemur length: 2.9; mesotibia length: 2.4; mesotibial fossula spongiosa length: 1.5; mesotarsi length: 1.1; mesotarsal segment ratio: 1.0: 2.1: 2.1; metacoxa length: 0.8; metatrochanter length: 0.7; metafemur length: 4.4; metatibia length: 5.0; metatarsi length: 1.9; metatarsal segment ratio: 1.0: 2.5: 2.0; abdomen length: 5.7; abdomen (widest) width: 2.7; pygophore length: 1.4; pygophore width (across widest point): 1.1.

Material examined: FRENCH GUIANA: Kaw Mountains, 2 km N. Route D6, MV light, 4°33.91’N, 52°9.38’W, 22 December 2000, V. R. Block, INHS Insect Collection 780,124 [1 male, holotype] ( INHS).

Distribution: Known only from the type locality ( Fig. 4 ).

Etymology: The specific epithet is the Latin adjective abolitus , - a, - um, formed from the Latin verb aboleo ‘to destroy, abolish, efface, annihilate, check the growth of, retard, decay’. This name was chosen to highlight the “effaced” sulci and granulations of the pronotal lobes.

Remarks: The new species is very similar to Rasahus scutellaris auct. (nec Fabricius, 1787) (see below) in structure, color pattern, and small size (both 10–10.5 mm in males). The color pattern also is similar to R. sulcicollis and to a lesser extent, R. castaneus , although their larger size precludes any of these species and their associated junior synonyms from being conspecific with R. abolitus sp. nov.

Morphologically, however, R. abolitus sp. nov. and R. scutellaris auct. differ markedly in the structure of the pronotum. Coscarόn (1983a) noted in her redescription of R. scutellaris auct.: “[English transl.] Anterior [pronotal] lobe with granulations in the sulci and more or less well-marked basal depression where joins the lateral internal sulci.” In contrast, the anterior pronotal sulci of the new species are not at all well marked, being rather obsolescent. Granulations also appear to be essentially absent in the lateral internal sulci, but in the external and middle lateral sulci minor sculpturing is apparent under higher magnification ( Fig. 3C ). Coscarόn (1983a) also noted of R. scutellaris auct.: “[English transl.] Posterior [pronotal] lobe with granulation, rugosities, and hairs.”, and the posterior pronotal lobe of the new species is very smooth, lacking any granulation (ignoring microsculpture). The anteocular part of the head also is a slightly longer, composing a larger proportion of the overall head length than in R. scutellaris auct. Two other species, i.e., R. albomaculatus and R. surinamensis , also lack granulations and well-defined sulci, but each possesses more extensive pale patterning on the hemelytra and is much larger (21–25 mm in R. albomaculatus and 16–18 mm in R. surinamensis ). Based on Coscarόn’s (1983a) plates, the genitalia closely resembles R. scutellaris auct., although R. abolitus sp. nov. might differ in possessing a more acuminated apex of the median process ( Fig. 5D ) and a less attenuated left paramere ( Fig. 5E, F ).

As mentioned, the color pattern is very similar to R. scutellaris auct. In addition to generally sharing the same pale maculations, both species appear to be distinctive in their bicolorous scutellum: black with a whitish spine. However, a few differences exist. First, the claval stripe does not extend beyond the base of the scutellar spine in R. abolitus sp. nov., occupying approximately the apical third of the clavus, whereas in R. scutellaris auct. the claval stripe extends well beyond the base of the scutellar spine, occupying at least the apical half of the clavus. Second, the oblique pale corial stripe adjacent to the clavus (paraclaval stripe) is essentially complete in R. abolitus sp. nov., whereas it is nearly interrupted near the base in R. scutellaris auct. Third, a pale marginal stripe connects the paraclaval stripe to the central corial spot and continues along the posterior margin of the hemelytra in R. abolitus sp. nov.; yet, this pale marginal stripe appears to be missing or obsolete in R. scutellaris auct. Fourth, the connexiva are pale in the basal half in R. abolitus sp. nov., rather than in the basal two-thirds in R. scutellaris auct. Finally, the apical pale spot of the membrane appears to follow the two apical veins, forming an inverted “Y”, in R. abolitus sp. nov., whereas the spot appears as a regular oval, enveloping the area between the two apical veins, in R. scutellaris auct. It is recognized that some of these color characters might be shown to vary intraspecifically in one or both species, as more specimens are examined.

Two other species of Rasahus were taken syntopically with R. abolitus sp. nov.: a single adult male of R. sulcicollis (INHS Insect Collection 780,186) and a single adult female of R. castaneus ( Fig. 6A ). The two specimens bear an identical locality label to the holotype of R. abolitus sp. nov. and were determined by the author. The latter specimen represents the first record of R. castaneus from French Guiana.

The identity of Reduvius scutellaris Fabricius, 1787 . In order to confirm that R. abolitus sp. nov. was not conspecific with R. scutellaris , images of the holotype of Reduvius scutellaris from ZMUC were studied. The species was described from “Cajennae” [=Cayenne, French Guiana] by Fabricius (1787), and Stål (1868) later reported that the single type specimen was greatly damaged, with only portions of the head, thorax, scutellum, clavus, [hemelytral] membrane, and [hind] wings remaining. Receiving these images ( Fig. 7 ) confirmed this highly-damaged status. However, the images also revealed that Rasahus scutellaris auct. (nec Fabricius, 1787) is not the same species as Reduvius scutellaris Fabricius, 1787 . Coscarόn (1983a) apparently had not studied the type of Reduvius scutellaris , nor had she examined material of this species from French Guiana.

It can be clearly seen that Reduvius scutellaris is a species of Rasahus in which a small pale spot is fully contained in the apical portion of the medial membranal cell, as opposed to R. abolitus sp. nov., the species referred to Rasahus scutellaris examined by Champion (1899: pl. 13, fig. 9), and the species referred to Rasahus scutellaris figured by Coscarόn (1983a: pl. 18, fig. A). Contrary to Coscarόn’s (1983a) redescription, Stål (1868) stated that the length of Reduvius scutellaris was 15 mm. The true identity of Reduvius scutellaris , based on plates in the revision (i.e., Coscarόn 1983a), should be one of the following species: R. amapaensis , R. arcitenens , R. arcuiger , or Rasahus rufiventris ( Walker, 1873) , as Coscarόn (1983a) had examined the type of each. Of these, R. arcitenens and R. arcuiger have a strong pale postscutellar macula (not apparent in holotype of R. scutellaris ) and a larger pale spot of the medial membranal cell. Similarly, R. amapaensis also possesses a postscutellar spot, although it is not as striking. Conversely, R. rufiventris ( Fig. 6B ) matches well the damaged holotype of Reduvius scutellaris in the lack of a distinct postscutellar spot, the shape of the arcuate spot of the cubital membranal cell, and the small spot of the medial membranal cell.

Thus, Pirates rufiventris Walker, 1873 is here considered to be a junior synonym of Reduvius scutellaris Fabricius, 1787 syn. nov. Additional specimens from the type locality compared with the remains of Fabricius’ mutilated type material will be useful to corroborate this status.

The identity of Pirates myrmecinus Erichson, 1848 . Given the confounded identity of R. scutellaris , images of the holotype of Pirates myrmecinus from ZMHB were also studied. This is the only junior synonym of R. scutellaris , which was established by Stål (1868); Cimex scutatus Gmelin, 1788 is clearly a misspelling of Fabricius’ specific epithet, as Gmelin referred to Fabricius’ original description. Like R. scutellaris , the holotype of P. myrmecinus ( Fig. 8 ) is badly damaged. Despite this damage, some important morphological features are still visible, allowing the status of this taxon to be further clarified. Simultaneously under study by me were two complete specimens from Belize that share these conspicuous morphologies (see Remarks below) and agree well with the holotype in other general facies. Thus, the taxon Pirates myrmecinus Erichson, 1848 , is here resurrected as a valid species, transferred to Rasahus , and redescribed, based on the Belizean specimens:

Figures

FIGURE 3. Rasahus abolitus sp. nov., adult male (holotype): (A) dorsal habitus; (B) lateral habitus; (C) pronotum, dorsal view; (D) pygophore, caudal view; (E) labels. Scale bar = 2 mm.

FIGURE 4. Map indicating type locality of Rasahus nesiotes sp. nov., R. deliquus sp. nov., and R. abolitus sp. nov.

FIGURE 5. Male external genitalia: (A–C) Rasahus deliquus sp. nov.: (A) median process of pygophore; (B) left paramere; (C) right paramere; (D–F) R. abolitus sp. nov.: (D) median process of pygophore; (E) left paramere; (F) right paramere; (G–I) R. myrmecinus stat. rev. et comb. nov.: (G) median process of pygophore; (H) left paramere; (I) right paramere.

FIGURE 6. Dorsal habitus: (A) Reduvius castaneus, adult female. Label data: FRENCH GUIANA: Kaw Mountains, 2 km N. Route D6, MV light, 4°33.91’N, 52°9.38’W, 22 December 2000, V. R. Block, INHS Insect Collection 780,125 [1 female] (INHS); (B) Reduvius scutellaris stat. rev. (=R. rufiventris), adult male. Label data: BRAZIL: Pará, Jacareacanga, (6°16’S, 57°44’W), 110 m., Dec. 1968, Moacir Alvarenga, Rasahus rufiventris (Walk.) det. J. Maldonado C. 1986, Rasahus scutellaris det. D. R. Swanson 2017 [1 male] (UMMZ). Scale bar = 2 mm.

FIGURE 7. Holotype of Reduvius scutellaris housed in ZMUC: (A) ventral habitus; (B) ventral habitus of head and pronotum; (C) dorsal habitus; (D) dorsal habitus of head and pronotum; (E) labels. Scale bar = 2 mm. Photographed by Mikkel Post (ZMUC); used with permission.

FIGURE 8. Holotype of Pirates myrmecinus housed in ZMHB: (A) lateral habitus, left side; (B) dorsal habitus; (C) ventral habitus; (D) head, pronotum, and forelegs, left lateral view; (E) thoracic pleura, right lateral view; (F) labels. Photographed by Jürgen Deckert (ZMHB); used with permission.

FIGURE 10. Protibial fossula spongiosa, lateral view: (A) Belizean male of Rasahus myrmecinus stat. rev. et comb. nov.; and (B) R. abolitus sp. nov. (holotype).

FIGURE 11. Metapleural sulcus, lateral view: (A) Belizean specimen of Rasahus myrmecinus stat. rev. et comb. nov., adult male; (B) idem., adult female; (C) R. abolitus sp. nov. (holotype); (D) R. albomaculatus; (E) R. biguttatus; (F) R. setosus; (G) R. sulcicollis; (H) Melanolestes picipes; and (I) Sirthenea stria carinata. Solid lines separate genera, dashed lines separate species.