Corresponding author: Hannelore Hoch (
Academic editor: Dávid Rédei
A new obligate cavernicolous (troglobitic) species in the planthopper family
A recent survey of limestone caves in the Iuiú municipality (Bahia state, Brazil) by a team of the Centro de estudos em Biologia Subterrânea, Federal University of Lavras, Brazil, revealed the existence of a previously unknown species belonging to the planthopper family
With currently 111 species in 21 genera,
The epigean
Although information on the biology and ecology of
The classification of
Unambiguous synapomorphies have not been identified for any of the established genera or tribes. Thus the accommodation of the new species within any of the existing supraspecific taxa is inherently problematic.
Following the key provided by
In characters of the male genitalia, the new cavernicolous species does not share any similarities with any species of the known kinnarid genera (in or outside
Small kinnarid (ca. 3 mm body length), strongly troglomorphic: compound eyes absent, tegmina reduced, wings vestigial, body pigmentation reduced (Fig.
Head. Vertex trapezoidal, short, ca. 3 × wider posteriorly than medially long, with a very faint median carina; anterior and posterior margin of vertex parallel. Frons narrow, ca. 1.8–2.0 × longer than maximally wide, widest between level of antennae and frontoclypeal suture, ca. 1.3 × longer than post- and anteclypeus together, surface medially smooth, devoid of a median carina, lateral margins distinctly ridged. Frontoclypeal suture nearly straight. Post- and anteclypeus with a distinct median carina. Rostrum elongate, in repose well surpassing hind coxae, third joint shorter than second. Compound eyes absent, their former position recognizable by a shallow, vaulted area. Median (frontal) ocellus absent, lateral ocelli vestigial. Antennae with scape short, subcylindrical, slightly expanding distally; pedicel subcylindrical, ca. 2.4 × as long as wide, with distinct sensory plaque organs; arista ca. 2.8 × as long as pedicel.
Thorax. Pronotum tricarinate, ca. 3 × wider than vertex posteriorly, short, posterior margin medially shallowly concave; carinae distinct, median carina attaining but not surpassing anterior margin of pronotum; lateral carinae medially more or less parallel to posterior margin, and joining posterior margin laterally. Mesonotum faintly tricarinate, ca. 1.3 × wider than medially long. Tegulae vestigial. Hind tibiae laterally unarmed, distally with 7 slender teeth, arranged in a shallow arc. First metatarsal joint distally with 4/5 and 5/6, 2nd metatarsal joint with 3/4 or 4/5 teeth (individually and bilaterally variable). Pretarsal claws and arolia small, inconspicuous. Tegmina (Fig.
Male genitalia. Genital segment bilaterally symmetrical, in lateral aspect short, ca. 3 × as high as medially long; in caudal aspect approximately figure-8-shaped, in upper third laterally constricted, with a narrow transversal bridge; anterior margin of genital segment smooth, without any conspicuous median apodemes; medioventral process prominent, broadly subtriangular, in lateral aspect distinctly exceeding caudal margin. Anal segment bilaterally symmetrical, short, stout, ventrally on each side with a compressed wing-shaped process. Parameres slender, narrow throughout, medially converging. Connective straight, narrow, almost terete.
Aedeagus bilaterally symmetrical, tubular, stout; periandrium with two large lateral lobes; proximal apodeme of aedeagus (= „tectiform structure“: term applied by
Females with abdominal tergites VI, VII and VIII bearing wax-fields. Female genitalia as in other
The genus name refers to Iuiú, the name of the municipality were the cave (type locality) is situated. The gender is feminine.
Habitus (Fig.
Body length. Measurements refer to distance between anterior margin of head to tip of abdomen (= caudal margin of parameres), those in brackets to distance of anterior margin of head to distal margin of tegmina.
Males. 2.8 (3.4)–3.8 (3.8) mm (n = 8). Females. 4.4 (4.0)–4.5 (4.1) mm (n = 2).
Colouration. Frons, vertex, pronotum yellowish, carinae contrasting dark brown; mesonotum more or less uniformly sordid yellowish; antennae and tegulae sordid light brown; tegmina translucent, uniformly yellowish-brown, veins slightly darker, without any conspicuous pattern. Metanotum, legs, as well as abdominal tergites and sternites pale yellow.
Configuration, shape and proportions of head and thorax as described for the genus.
Male genitalia (Fig.
External female genitalia (Fig.
Female abdomen and external genitalia. = Vll. sternite = gonocoxae VIII = anal segment (X. segment) = anal style (XI. segment) = tergites of segments VI-VIII
The species is only known from the “Lapa do Baixão” cave in Iuiú municipality, Bahia State, Brazil. The external vegetation in the area corresponds to the “Caatinga” formation, the only xeric biome of the country, with xeromorph, decidual vegetation (Fig.
The “Lapa do Baixão” cave formed within limestones from the “Bambuí” geological group, from the Neoproterozoic, with ages ranging from 650-850 Myr. This group comprises the largest limestone formation in Brazil, embracing most of the known Brazilian limestone caves (Fig.
The Baixão cave possesses dozens of roots, mainly observed in the first portion of the cave (Fig.
Unfortunately, it was not possible to associate the roots to any particular plant species in the surface vegetation, but considering the distance between the surface and the cave, it appears likely that such roots belong to substantial trees with pivotant roots systems, capable of penetrating deep inside the cracks into the soil and rock until reaching the cave chambers.
Such roots shelter a variety of invertebrate species which feed especially in their decomposing parts. However, also many non-troglomorphic
They were only rarely observed on the same roots where the non-troglomorphic
The species epithet “
Holotype male. Brazil. Bahia State, Iuiu municipality, Toca Lapa do Baixão (
Paratypes: 2 males, same data as holotype. 5 males, 2 females, same data as holotype, except 9.vii. 2014, in coll. Universidade Federal de Lavras, ISLA.
In the cave, several 4th and 5th instar nymphs of
The placement of
Thus it cannot be excluded that the closest epigean relative (whether extant yet unknown or extinct) displayed a median carinae of the frons and a darkly pigmented integument.
The genera currently featured in
No close epigean relatives could be identified for
It is certainly difficult to formulate a well-supported hypothesis regarding the evolution of the subterranean lineages of the Brazilian planthoppers, mainly due to the lack of knowledge on the epigean
However, the structure and age of the rocks housing cave environments seem to be important factors acting on the evolution or at least on the distribution pattern of the cavernicolous
1.
2. Populations of the kinnarid
3.
The external area surrounding the cave is heavily impacted, mainly by human activities such as agriculture and extensive breeding of cattle and goats. Moreover, the area is currently being evaluated for its potential for limestone extraction. Hence, although there are no mining activities yet in the area, such activities will probably start in a near future, posing a potential risk to the cave environment. A new railway (FIOL–Ferrovia de Integração Oeste-Leste) that is being constructed connecting the Brazilian coastal area to this inner portion of Bahia state will favour the outflow of feedstock (especially agricultural products and ore), which will certainly contribute to arising the interest of exploiting the limestone in the area. Fortunately, the cave did not show any indication of human visitation, thus we consider the best option for the moment in order to preserve the cave may be to not publicly disclose the precise GPS data of its location.
It is worth mentioning that the Lapa do Baixão cave has many other troglobitic species (12 species) from which only two are currently described:
Accordingly, Toca do Baixão cave certainly has potential to become a hotspot in the future, since only a few samplings were conducted there. Therefore, it is crucial that Brazilian government earmark some conservation efforts to preserve this unique cave and its endemic inhabitants.
The discovery of
We would like to express our sincere thanks to our colleagues Marconi Souza Silva (UFLA) and Luiz Felipe Moretti Iniesta for helping with collections, and to our colleagues at the Museum für Naturkunde, Berlin: Manfred Uhlig for the male habitus photograph (Fig.