Brachysandalus howarthi Malipatil & Liu 2024, sp. nov.
Creators: name: Liu, Yingqi
name: Cai, Wanzhi
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hemiptera
Reduviidae
Brachysandalus
Brachysandalus howarthi

description: Brachysandalus howarthi Malipatil & Liu, sp. nov.
(Figs. 28–30)
Type specimens. Holotype male, Australia, Queensland, Bayliss cave in Undarra lava tunnels via Mt Surprise, Stn 6, 13.vi.1986, Howarth & Robson (QM). Paratypes: 1 male (dissected), same as holotype (QM); 1 male, Bayliss cave, Mt Surprise,, Stn 7, on floor, 12.i.1989 (QM); 1 male, Bayliss cave, Mt Surprise, Undarra, 700 m, in extension crawl, 10.i.1989, H. Hoch, F.G. Howarth, M. Ashe (QM); 1 male, Mt Surprise, Mt Garnet: Undarra, Bayliss cave on the wall, 31.v.1986, F.G. Howarth, D. Irvin & Collis (QM); 1 male, Bayliss cave, Mt Surprise, Rosella Plains Stn, 700 m, 28.v.1986, F.G. Howarth & D. Irvin coll. (QM).
Diagnosis.
Only submacropterous male known, body medium-large sized. Generally brown to dark-brown, eyes and ocelli bright red, hemelytron with distal 1/2 to 2/3 of clavus and corresponding adjoining area of corium between Pcu+1A and Cu yellow (Fig. 28). Body generally covered with dense, short bristly, golden to yellowish brown, sub-shiny setae obvious on head, pronotum, scutellum and hemelytron (Fig. 28); antennal scape elongate, subequal to head length; eyes reduced (Fig. 28A&C), not reaching dorsal and ventral margins in lateral view (Fig. 28C); ocelli small, not raised above surface (Fig. 28A); fore femur armed below with sparse tubercles about six each in two rows separated by a very shallow furrow, tubercles varying in size, in addition with bristly setae along with pilosity, mid femur not armed with tubercles (Fig. 28B&C); fore tibia with fossula spongiosa occupying about 1/3 to 2/5 tibial length, extending post base of tarsi flaplike almost 1/2 fossula spongiosa length, mid tibia with fossula spongiosa slightly more than 1/3 its length (Fig. 28B&C); in male, sternite VII on left side with conspicuous extragenital structure in form of a large, broad hook-shaped, plate-like process close to posterior margin of sternite, curved outwardly on abdominal integument (Figs. 28B, 29, 55B, 56B); male genitalia with median pygophore process straight, oblique to right side, venter strongly ridged in caudal view (Fig. 30B), slenderly spatulate, slightly narrowly at base and gradually narrowing to a point at apex in lateral view (Fig. 30C); inner margin of lateral phallothecal sclerite weakly undulate (Fig. 30I).
Description.
Submacropterous male (Fig. 28)
Colouration (Fig. 28): Generally brown to dark-brown, with abdomen, thoracic venter, distal three segments of antenna, eyes, ocelli, parts of femora and tibiae of all legs with variable shades of ferruginous yellow brown (variable within type series); eyes and ocelli bright red; distal 1/2 to 2/3 of clavus and corresponding adjoining area of corium between Pcu+1A and Cu yellow; claws slightly darker than their tarsi.
Structure (Figs. 28–30): Body medium-large sized, generally covered with dense, short bristly, golden to yellowish brown, sub-shiny setae obvious on head, pronotum, scutellum and hemelytron; venter of body and legs also with less dense, longer, shiny setae; surface of head, pronotum and scutellum rather rough, not smooth, or shiny.
Head: Narrow elongate fusiform, wholly covered with dense bristly setae, some slightly darker and thicker bristle-like on mandibular plates, shiny longer bristly setae on dorsal aspect of labial segments. Head ventrally near base with a large ‘wart-like’ area postero-ventral to each eye, wart-like area smooth, pale in colour and devoid of setae. Anteocular region triangular, clypeus near its base slightly elevated near base above mandibular plates. Interocular region with arcuate convex sulcus at posterior border of eyes, sulci conspicuous dorsally with a small elongate pit medially between ocelli. Postocular region almost rounded to neck. Neck with lateral tubercles not obvious. Antennal segments with short whitish pilosity and sparse longer setae, scape thickest, pedicel thinner, then basi-and distiflagellum thinnest. Eyes reduced, not reaching dorsal and ventral margins in lateral view. Ocelli small, not raised above surface, separated from each other by less than twice diameter of single ocellus, separated from eye by slightly more than diameter of single ocellus. Labium with second and third visible segments covered with long bristly setae particularly on ventral aspect, basal segment hairy like head. Labrum about 1/3 to 1/2 length of first visible labial segment.
Thorax: Anterior lobe of pronotum with integument fairly rugulose, not smooth, with a shallow median longitudinal sulcus in basal 1/3 to 1/2. Posterior pronotal lobe short, arcuately quadrate, integument roughly finely rugulose, with short bristly pilosity, humeri rounded, posterior margin convexly rounded. Scutellum triangular, disc slightly depressed in basal 1/3, lateral ridges in apical 2/3 raised and produced to rounded elongate spine-like scutellar process, apex of process horizontal in lateral view, integument with long bristly hairs. Meso-and metanotum generally also rugulose. Propleuron with integument not granulate, smoothly pilose, set off from dorsal surface by an indistinct carina. Mesopleuron integument also not granulate, sparsely pilose. Metapleuron with integument very finely granulate, granules do not striate, metapleural sulcus distinctly bicarinate and curved, pilose with whitish dense longer setae posteriorly. Mesosternum carinate in middle, metasternum with disc tumid. Hemelytron rather conspicuously narrowed, posteriorly narrowing, and extending to anterior margin or anterior 1/3 of abdominal tergite VII and exposing broad lateral areas of abdominal terga including connexiva. Maximum width of hemelytron in situ from above much less than 1/2 maximum width of abdomen.
Legs: Fore leg with coxa with shiny yellow pilosity particularly in distal 1/2; femur strongly fusiform, greatly incrassate near base narrowing distally, much thicker than other femora, armed below with sparse tubercles about six each in two rows separated by a very shallow furrow, tubercles varying in size, in addition with bristly setae along with pilosity; tibia cylindrical, more or less straight, fossula spongiosa occupying about 1/3 to 2/5 tibial length, extending post base of tarsi flaplike almost 1/2 fossula spongiosa length, tarsi thin and elongate, with denser short pilosity ventrally. Mid leg with coxa globular, femur only slightly thickened, not armed with tubercles, only dense spine-like bristles, tibia with shiny yellow pilosity, with fossula spongiosa slightly more than 1/3 its length. Hind leg with femur very long, cylindrical, tibia also cylindrical, brushy hairs ventrally and apically like on mid tibia, hind coxae also globular. Claws of all legs well developed.
Abdomen: Dorsally elongate ovate, sternum carinate in midline and slightly curved to right side of body, smooth, covered with fine pilosity, and longer setae on sternum (Fig. 28B), sternite VII on left side with conspicuous extragenital structure in form of a large, broad hook-shaped, plate-like process close to posterior margin of sternite, curved outwardly on abdominal integument (Figs. 28B, 29, 56B, 57B). Connexivum with conspicuous golden pilosity as elsewhere on sternum, abdominal sterna and terga entire. Spiracles situated about middle of each segment. Each spiracle with spot-like smooth impressed not obviously visible areas, one anteriorly close to anterior margin and one postero-ventrally on each sternite.
Male genitalia (Fig. 30): Median pygophore process straight, oblique to right side, venter strongly ridged in caudal view (Fig. 30B); slenderly spatulate, slightly narrowly at base and gradually narrowing to a point at apex in lateral view (Fig. 30C). Parameres (Fig. 30D&E) with outer surfaces densely covered with brown hairs, left paramere (Fig. 30D) falcate with apex truncate, right paramere (Fig. 30E) subtriangular and curved in middle, right paramere only slightly broader and shorter than left paramere. Phallus (Fig. 30F–I) in resting condition with basal plate subequal to length of basal plate bridge (Fig. 30F), pedicel thick and subequal to length of basal plate (Fig. 30H&I); length of struts distinctly longer than half length of phallosoma (Fig. 30F); apex of dorsal phallothecal sclerite arcuate (Fig. 30F); lateral phallothecal sclerite subquadrangular, inner margin weakly undulate (Fig. 30I); pair of slender sclerites near base of venter of phallosoma strongly sclerotized (Fig. 30G).
Measurements: [of holotype male, followed by one paratype male]. Body length 17.20, 17.50; maximum width of abdomen 5.46, 4.80; length of head 2.58, 2.57; length of anteocular region 1.14, 1.20; length of postocular region 0.57, 0.54; width of head across eyes 1.67, 1.70; width of interocular space 0.95, 0.95; width of interocellar space 0.22, 0.30; length of eye in dorsal view 0.68, 0.68; width of eye in dorsal view 0.30, 0.30; lengths of antennal segments I–IV 2.47, 2.43 / 4.37, 4.50 / 4.96, 4.80 / 3.61, 4.00; length of visible labial segments I–III 1.06, 1.10 / 1.78, 1.74 / 0.66, 0.62; length of pronotum 3.99, 3.95; length of anterior pronotal lobe 2.66, 2.69; length of posterior pronotal lobe 1.25, 1.21; width of anterior pronotal lobe 3.23, 3.26; width of posterior pronotal lobe 3.85, 3.80; length of scutellum 1.59, 1.33; maximum width of scutellum 2.01, 1.50; length of hemelytron 10.14, 9.50; length of fore tibia 4.18, 4.10; length of fossula spongiosa on fore tibia 1.25, 1.52.
Distribution. Australia (Queensland).
Etymology. The species is named after Dr. Francis G. Howarth (formerly Bishop Museum, Honolulu), the primary collector of the type series, and who provided the below biological information on the species based on his extensive field observations.
Comparative notes. This species may be readily distinguished by the following combination of characters. The elongate antennal scape that is subequal to head length, the conspicuously narrowed hemelytron, the reduced eyes and ocelli, and the body generally covered with very short brushy setae.
Remarks. There is slight variation in general body colour within the type series.
Biology. Brachysandalus howarthi sp. nov., reported as Peirates sp. 1 in Eberhard & Howarth (2021), is morphologically and behaviourally adapted to live in caves and is regarded to be an obligate subterranean species. The species has been collected only within the deep zone of Bayliss Cave, a 1,300 m long lava tube, 25 km southeast of Mt Surprise, North Queensland. The average passage width and height is 8 by 5 m respectively (maximum 25 by 11.5 m).
The deep zone in Bayliss Cave includes the passage beyond a constriction that isolates the interior environment from that in the outer portion of the cave. The constriction is 350 m downslope from the only known entrance (Howarth & Stone 1990). The deep zone environment is extreme, being perpetually dark and containing high concentrations of carbon dioxide, which ranges from 3% to more than 6% by volume (Howarth & Stone 1990). The atmosphere remains at a nearly constant temperature of 27°C and is stagnant and saturated to supersaturated with water vapor. The ceiling, walls, and floor are wet from condensing vapor. The floor is mostly covered by a few centimetres thick layer of semi-fluid clay along with widely scattered small patches of bat guano. Large curtains of tree roots (most likely Eucalyptus species) hang from the ceiling and occasionally extend to the floor (see figure 5 in Eberhard & Howarth 2021).
Bayliss Cave contains one of the most diverse obligate cave faunas in the world with 25 of the 51 resident species of arthropods obligately adapted to subterranean life (Eberhard & Howarth 2021). Significantly, the distribution of each of the obligate cave species in Bayliss Cave is positively correlated with the concentration of carbon dioxide (Howarth 1988, Howarth & Stone 1990).
Brachysandalus howarthi sp. nov. has been observed hunting on the wet muddy floor and lower walls, and adult was captured feeding on an advanced stage nymph of the obligate cave cockroach (Neotemnopteryx baylissensis Slaney, 2000) on the floor in the middle of the passage about 4 m from the wall (see figure 7g in Eberhard & Howarth 2021). Like other obligate cave species (Howarth & Moldovan 2018), it moves very slowly, cautiously, and deliberately, moving one leg at a time when walking. It shows no reaction to light. As envisioned for the Hawaiian cave animals (Howarth 1983), the cave-adapted fauna in Bayliss Cave, including Brachysandalus howarthi sp. nov. could have colonized the voids and caves within the Undara lava flow from a neighbouring older flow. Thus, the age of the cave may not indicate a maximum age of cave adaptation.
description: Published as part of Liu, Yingqi & Cai, Wanzhi, 2024, Revision of Australian Brachysandalus with the description of nine new species including one cavernicolous species (Hemiptera: Heteroptera: Reduviidae), and observations on male extragenital structure and leg teratology, pp. 1-112 in Zootaxa 5490 (1) on pages 57-61, DOI: 10.11646/zootaxa.5490.1.1, http://zenodo.org/record/13211621