Medical and Veterinary Entomology (2002) 16, 75±82
A new species of Triatominae from Tamil Nadu, India C . G A L V AÄ O * , J . S . P A T T E R S O N y, D . D A S I L V A R O C H A * , J . J U R B E R G * , R . C A R C A V A L L O * , K . R A J E N z, D . P . A M B R O S E z and M . A . M I L E S y *
LaboratoÂrio Nacional e Internacional de RefereÃncia em Taxonomia de TriatomõÂ neos, Departamento de Entomologia, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brazil, yPathogen Molecular Biology and Biochemistry Unit, London School of Hygiene and Tropical Medicine, London, U.K. and zEntomology Research unit, St Xavier's College, Palayankottai, India
Abstract. A new species of the genus Linshcosteus Distant, 1904 (Hemiptera: Reduviidae: Triatominae) is described from specimens collected near Kalakkadu, Tamil Nadu state, southern India. Specimens were found in deep crevices between rocks, in a region of semi-arid scrub jungle. The distinctiveness of the new species was demonstrated by a morphometric analysis including the five previously described species of Linshcosteus, all from India. Nine measurements of the head were used in an isometric size-free principal component analysis. In terms of discrete morphology the new species, Linshcosteus karupus sp.n. GalvaÄo, Patterson, Rocha & Jurberg differs from the most similar one, L. kali Lent & Wygodzinsky, 1979, by its very prominent anterolateral projections of the pronotum, by the length to width ratio of the pronotum, by the pilosity of the head and several other characters, including phallic structures. A revised key is presented for the six species of the genus. Key words. Linshcosteus karupus, Reduviidae, Triatominae, morphometrics, new species.
Introduction The subfamily Triatominae is organized into six tribes with 18 genera, composed of 134 species, all characterized by their obligate haematophagy. The great majority of species are found only in the New World, where several are important as vectors of Trypanosoma cruzi Chagas, 1909, the causative agent of Chagas disease or American trypanosomiasis (Lent & Wygodzinsky, 1979; Carcavallo et al., 2000). The genus Linshcosteus Distant, 1904, is restricted to the Indian subcontinent. Only one species, Linshcosteus carnifex Distant, 1904, was known until Ghauri (1976) described two more species, L. confumus and L. costalis. Later, Lent & Wygodinsky (1979) described another two species, L. chota and L. kali. The genus is well characterized (Schaefer & CoscaroÃn, 2001) and can be easily
Correspondence: James Patterson, Pathogen Molecular Biology and Biochemistry Unit, Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, U.K. E-mail:
[email protected] #
2002 The Royal Entomological Society
differentiated from other Triatominae by absence of the stridulatory sulcus and by a short rostrum, not reaching the prosternum. Lent & Wygodzinsky (1979) designated these characteristics as apomorphic characteristics of the genera of the tribe Triatomini. Gorla et al. (1997) showed, based on morphometric analysis, that all species of Linshcosteus were unrelated to the species of Triatoma recorded from the Old World and suggested an independent Old World origin for Linshcosteus, a view supported by Schofield (2000). Schaefer (1998) commented on the divergent opinions of several authors as to the taxonomic position of Linshcosteus within the subfamily Triatominae, concluding that studies on the phylogenetic relationships of Linshcosteus with other Triatominae should be based not only on morphology, but also on biological and behavioural data. In response to these arguments and the morphological distinctiveness of the genus, Carcavallo et al. (2000) made an adjustment to the taxonomy of the Triatominae by removing Linshcosteus from the tribe Triatomini to create the new tribe, Linshcosteini. In August 2000 approximately 30 specimens of the genus Linshcosteus were collected close to Kalakkadu, Tamil Nadu state, south India (77 290 21.600 E, 8 350 6600 N, 143 m a.s.l). The insects were found at a single locality, 75
76 C. GalvaÄo et al. an exfoliated sedimentary rock formation, approximately 10 m high and 40 m in length, situated on an expanse of semi-arid scrub, sparsely populated by xerophytic vegetation (Fig. 1b). The bugs were captured from deep fissures and crevices in the rock (Figs 1c,d). Examination of the specimens revealed the characters of a new species, which is described below. A pair of adults and seven nymphs were kept alive to create a colony, now maintained in the insectary of the LaboratoÂrio Nacional e Internacional de RefereÃncia em Taxonomia de TriatomõÂ neos do Departamento de Entomologia, Oswaldo Cruz Institute (FIOCRUZ), Rio de Janeiro, where the species is being studied. Preliminary observations have shown that the new species of Linshcosteus is able to feed on pigeons (Columba livia), mice (Mus musculus) and humans. Hind gut dissection of some of the field-caught bugs revealed the presence of trypanosomatid flagellates, with epimastigote and small metacyclic trypomastigote forms (Patterson et al., 2001a). Preliminary observations of the morphology of these trypanosomatids suggests similarity to T. conorhini, but this requires confirmation. Description Linshcosteus karupus sp. n., GalvaÄo, Patterson, Rocha & Jurberg. Length of < 21±23 mm, of , 22±23 mm; pronotum width of < 4.8±5.6 mm, of , 5.1 mm; maximum abdomen width of < 8.1±10.4 mm, of , 11.6 mm. Overall colour black, pilosity short and inconspicuous. Head black, with numerous setiferous granules, except for a central narrow strip extending the length of the ventral surface; pilosity spread and inconspicuous. Head distinctly longer than pronotum (1 : 0.77) and over twice as long as wide (1 : 0.41). Anteocular region four times as long as postocular (1 : 0.25). Postocular region not strongly convex below with sides faintly rounded, widest behind middle. Clypeus gently widened on posterior half, not strongly elevated in side view. Genae pointed apically, extending beyond level of apex of clypeus, almost attaining level of anteclypeus. Jugae acute but not pointed apically. Eyes in lateral view not attaining level of upper surface of head. Ratio width of eyes to synthlipsis 1 : 2.1. First antennal segment not attaining level of apex of clypeus; second segment with decumbent setae shorter than diameter of segment. Ratio of antennal segments 1 : 5.5±5.7 : 2.8±3.1 : 2.2±2.7. Rostrum with hairs shorter than diameter of segments. Apex of first rostral segment falling distinctly short of level of apex of antenniferous tubercle; apex of second segment attaining level of anterior margin of eyes; third segment attaining or slightly surpassing level of hind margin of eyes. Ratio of rostral segments 1 : 1.6 : 0.42. Anterior lobe of pronotum black, strongly convex; interlobe groove very conspicuous; ridges granulose, anterolateral projections very prominent. Posterior lobe black, rugose-granulose; submedian carinae well elevated, not extending beyond middle of posterior lobe. Humeral #
angles narrowly rounded, slightly projecting, pointed. Ratio length to width of pronotum: 1 : 1.35. Scutellum rugose transversally, its centre only faintly depressed. Posterior process shorter than main body of scutellum, horizontal, elongate and conical, narrowly tapering apically. Legs uniformly black and slender. Hemelytra falling short of base of seventh urotergite. Clavus and corium black; membrane fumose, very dark; veins brown. Abdomen very wide, with lateral portions of urostergites amply exposed. Spiracles brown, adjoining connexival sutures. Abdomen dark, including intersegmental sutures, connexivum margins brown in colour. Venter slightly flattened longitudinally along midline. Setae short, numerous but not conspicuous. Male genitalia. The phallus is characterized by the presence of a long articulatory apparatus, longer than the aedeagus (Fig. 13). It has a large median extension of the basal plate (Eplb), rectangular-shaped, smaller than the basal plate (Plb), which is cylindrical with a strong free apex from where the dorsal connections (Cd) emerge, having at the apex the capitate processes (Prc) (Fig. 13). The gonopore process (PrG) is cylindrical; the apical twothirds are hollow, and the basal third compact, where it joins the basal bridge (Fig. 14). The aedeagus is ovoid and shows four structures. The support of phallosome or struts (SPh) extend the entire length of the aedeagus, with a cylindrical base that bifurcates into two parallel arms, slightly divergent and rejoining at the apex (Fig. 14). 1 1 processes of endosome (PrEn), laminar, striated without spines at the apex, the edge of which is rounded (Fig. 13). The vesica (V) is vestigial, strongly chitinized, triangular-shaped, with the dorsal area slightly elevated and the lower one smooth (Figs 12 and 13). Phallosome (Ph) ovoid (Figs 12±14). Parameres are cylindrical, roller shaped, with a small triangular projection at the apex, with a few bristles on the external side (Figs 9 and 10). Median process of pygophore triangular, with rounded apex, fixed on a lightly arched base with a few bristles (Fig. 11). Etymology. karupus is derived from the Tamil word for dark or black. Material examined. Linshcosteus karupus sp. n. Holotype,
