Research Article |
Corresponding author: Maks Deranja ( maks.deranja@gmail.com ) Corresponding author: Niko Kasalo ( niko.kasalo5@gmail.com ) Academic editor: Zhu-Qing He
© 2022 Maks Deranja, Niko Kasalo, Karmela Adžić, Damjan Franjević, Josip Skejo.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Deranja M, Kasalo N, Adžić K, Franjević D, Skejo J (2022) Lepocranus and Valalyllum gen. nov. (Orthoptera, Tetrigidae, Cladonotinae), endangered Malagasy dead-leaf-like grasshoppers. ZooKeys 1109: 1-15. https://doi.org/10.3897/zookeys.1109.85565
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Only two leaf-like pygmy grasshopper species and specimens are known from Madagascar: the Leatherback Pygmy Grasshopper (Lepocranus fuscus Devriese, 1991) —which has a relatively low median carina of the pronotum; and the Malagasy Litterhopper (Valalyllum folium gen. et. sp. nov.), herein described — which has a high median carina. Lepocranus fuscus is known from the rainforests around Tampolo, Manakambahiny, and Mahavelona (Foulpointe). The new taxon, Valalyllum folium gen. et. sp. nov. is known only from the Belanono forest. Both species inhabit northeastern Madagascar. The new species could be rare or not-easy-to-spot in the rainforest leaf litter, where it most probably lives. A new tribe, Valalyllini trib. nov., is described for the two mentioned genera because its members are different from the Caribbean leaf-like Choriphyllini Cadena-Castañeda & Silva, 2019, from the African leaf-like Xerophyllini Günther, 1979, and from the Asian leaf-like Cladonotini Bolívar, 1887. A tabular key to the tribes of Cladonotinae with leaf-like representatives is provided, together with photographs of type specimens of both species belonging to the newly described tribe. The holotype of the new species belongs to the Muséum national d’Histoire naturelle Orthoptera collection, Paris.
Gondwana, identification traits, mimicry, new genus, new species, new tribe, phylogenetic position, rainforest, taxonomy, Valalyllini
Leaf mimicry in animals has evolved independently a number of times (
Until now, only a single leaf-like species of Tetrigidae was known to inhabit Madagascar—the Leatherback Pygmy Grasshopper, Lepocranus fuscus (
Museum acronyms used were MNCN for Museo Nacional de Ciencias Naturales (Madrid) and MNHN for the Muséum national d’Histoire naturelle. Taxonomy follows the Orthoptera species file (
Order Orthoptera
Suborder Caelifera
Infraorder Acrididea
Altogether, 76 Tetrigidae species (including the new one) are known to inhabit Madagascar, of which 73 (= 96%) can be found only in Madagascar and nowhere else in the world (
This diverse and polyphyletic family includes altogether 314 species assigned to 74 genera (
Altogether, 18 Tetrigidae species of Madagascar are assigned to the subfamily Cladonotinae: two members of Valalyllini trib. nov. (L. fuscus and V. folium); 13 species of the genus Thymochares, which is currently not assigned to any of the tribes, and it is questionable whether it represents a genus of Cladonotinae; Microthymochares pullus, an endemic genus and species with the same taxonomic problem as Thymochares; Epitettix spheniscus also with the same problematic assignment; and Xerophyllini and its member Morphopoides madagascariensis (
Cladonotini
(partim):
Valalyllum gen. nov., herein described (see below), type species V. folium sp. nov., also described herein.
Two monotypic genera, Lepocranus (including only L. fuscus) and Valalyllum gen. nov. (including V. folium sp. nov.). Lepocranus fuscus is endemic to the rainforests east of Mahavelona (Foulpointe) (
Members of Valalyllini (Lepocranus, Valalyllum gen. nov.) are very similar to and thus most likely closely related to Asian Cladonotini (genera Misythus Stål, 1877, Hymenotes Westwood, 1837, Holoarcus Hancock, 1909) and Caribbean Choriphyllini (Choriphyllum Serville, 1838 and Phyllotettix Hancock, 1902). Head, pronotum and legs in these three tribes show remarkable similarity and are regarded as homologous. Superficially, the leaf-like morphology of Valalyllini trib. nov. also resembles that of leaf-like Xerophyllini, but detailed comparisons reveal no homologous parts.
Antenna shorter than hind femur; vertex very wide; vertex slightly and obliquely elevated above the compound eyes; vertex without horns; upper margin of the antennal grove in the level of the lower margin of a compound eye; pronotal tip of the pronotum projected above the head, but not before the eyes or before the face; transverse pronotal veins weak, almost unrecognizable; pronotal tip obliquely bilobate in dorsal view; legs smooth, only with weak (small) undulations and triangular projections, not toothed or sawed. Found only in Madagascar.
Table
Tabular key to the four Cladonotinae tribes with leaf-like representatives (Valalyllini trib. nov. from Madagascar, Choriphyllini from the Caribbean, Cladonotini from SE Asia, and Xerophyllini from Africa).
Valalyllini trib. nov. | Choriphyllini | Cladonotini | Xerophyllini | |
---|---|---|---|---|
Distribution | Madagascar | Caribbean | Philippines, Papua | Tropical Africa |
Antenna | short | long or short | short | short |
Vertex horns | absent | absent | absent | present |
Upper margin of the antennal groove | on the level of the lower margin of a compound eye | on the level of the lower margin of a compound eye | on the level of the lower margin of a compound eye | below the lower margin of a compound eye |
Anterior tip of the pronotum | not falling in front of the face | strongly projected in front of the face | projected in front of the eyes | variable, not falling in front of the face (Trypophyllum) or projected in front of the face (Xerophyllum) |
Transverse veins on the pronotum | weak | strong | very strong | weak |
Posterior tip of the pronotum | obliquely bilobate | pointed | variable (pointed in Misythus, bilobate in Cladonotus) | pointed |
Legs texture | smooth, with small protrusions | smooth | toothed or spiky | toothed or spiky |
Lepocranus:
Lepocranus fuscus, by original designation and by the original monotypy.
A single species only (L. fuscus), endemic to the Malagasy rainforests east of Mahavelona (Foulpointe), such as Tampolo, where the holotype is from, and Manakambahiny (reported in
Complex noun, male in gender, composed of Latinized Ancient Greek “lepos” (λέπος), meaning bark, and “chranos” (χράνος), meaning helmet (
Same as for the species, see below.
Lepocranus fuscus:
Holotype. Madagascar • 1♂; “Foret de Tampolo, Madagascar”; May. 1932; A. Seyrig leg.; MNCN 7230.
Small (< 10 mm long), apterous, leaf-like, cryptic species endemic to northern Madagascar. Antennae are short and filiform, composed of 15 antennomeres. The upper margins of the antennal groove are at the lower margin of a compound eye. Frontal costa bifurcates between the eyes into rounded facial carinae (parallel in Valalyllum gen. nov.), between which there is a wide scutellum, as wide as a compound eye. Vertex obliquely projected above the eyes in frontal view. Vertex about 3 times wider than a compound eye. In the frontal view, a compound eye is rounded (ovoid in Valalyllum gen. nov.). Pronotum is leaf-like, 2.4 times as long as high (1.75 times in Valalyllum gen. nov.) because of the compressed and elevated median carina. In the dorsal view, the median carina of the pronotum is sulcate. Median carina of the pronotum is straight in the dorsal view (undulated in Valalyllum gen. nov.). Pronotum dips above the head in dorsal view, then smoothly curves upwards and gradually descends towards the posterior apex at an obtuse angle (150° slope, already reported in
Latin adjective in male gender, “fuscus, -a, -um” meaning brown (
Leatherback Pygmy Grasshopper (
(male holotype). Body length: (from the tip of the head to the tip of the subgenital plate) 8.6 mm (cited 9.8 mm in
Madagascar, Tampolo.
The Leatherback Pygmy Grasshopper was listed as an endangered species on the IUCN Red List because (1) the minimal geographic range it inhabits (the extent of occurrence is only about 3000 km2), (2) the population seems to be fragmented, and (3) the decline in both the number of mature individuals and the size and quality of the range area due to inferred severe deforestation (
Valalyllum folium gen. et sp. nov., here described, by original monotypy.
A single species only (V. folium), endemic to Madagascar (Belanono).
Noun of neuter gender. From Malagasy “valala” or “vahalala”- grasshopper and Latinized Ancient Greek “phyllum” - leaf
Same as for the species, see below.
Holotype. Madagascar • 1 ♂; East Madagascar, Belanono, “30 km SW de Sambava, sur la route d’Andapa” [along the road to Andapa]; Valdon and Peyrieras leg.; MNHN.
Large (> 11 mm long), apterous, leaf-like, rectangular, and cryptic species endemic to northern Madagascar. Antennae are short and filiform, composed of 15 antennomeres. Upper margins of the antennal groove in the level of the lower margin of a compound eye. Frontal costa bifurcates between the eyes into parallel facial carinae (more rounded in Lepocranus), between which there is a wide scutellum, as wide as a compound eye. Vertex obliquely projected above the eyes in the frontal view. Vertex about 3 times wider than a compound eye (measured at its widest part as seen in the frontal view). In the frontal view, a compound eye is ovoid (rounded in Lepocranus). Pronotum is rectangular and 1.75 times as long as high (2.4 times in Lepocranus) because of the compressed and elevated median carina. In the dorsal view, the median carina of the pronotum is sulcate. Median carina of the pronotum is undulated in a sinusoid fashion in the dorsal view (straight in Lepocraus). Pronotum dips above the head in dorsal view, then smoothly curves upwards and sharply descends towards the posterior apex. The posterior slope of the pronotum is abrupt (gradual in Lepocranus), forming a right-angle (obtuse angle in Lepocranus), and undulated. The posterior apex of the pronotum is bilobated in the dorsal view. Pronotum covers the whole abdomen (last segments not covered in Lepocranus). Dorsal margin of the hind femora bears three small projections (lappets). Genicular and antegenicular teeth are small and angular. Mid tibia is stout. Top margins of the mid and the fore femora lack tubercules. Pulvilli of the hind tarsi are rounded.
The specific epitheton is a noun in apposition, from Latin “folium, -i, n.” leaf, because of the species’ leaf-like morphology.
Malagasy Litterhopper
Holotype (male). General appearance. Valalyllum folium gen. et sp. nov. is a large (> 11 mm); smooth; rectangular; cryptic; dead-leaf-mimicking species with fine leaf-like venation on the elevated part of pronotum; uniformly brown except for the yellowish tarsi of all legs, as well as pale-yellowish hind tibiae.
Head. Antenna (Fig.
Pronotum
In the frontal view (Fig.
Legs. Fore legs (Fig.
(male holotype). Body length (from the tip of head to the tip of the subgenital plate) 11.3 mm. Pronotum length 13.4 mm. Pronotum maximum height 7.6 mm. Pronotum width between lateral lobes 5.2 mm. Pronotum width between the shoulders 3.5 mm. Eye width 0.4 mm. Vertex width 1.2 mm. Fore femur length 2.5 mm. Fore femur width 0.8 mm. Mid femur length 3.3 mm. Mid femur width 0.9 mm. Hind femur length 7.5 mm. Hind femur width 2.8 mm. Hind femur length/width ratio 2.7.
Madagascar, Sava region, Belanono (rainforest between Sambava and Adapa).
Similar to the Leatherback Pygmy Grasshopper (Lepocranus fuscus) (
The diversity and the distribution of the tribe Valalyllini trib. nov. (Valalyllum folium gen. et sp. nov. in the north, and Lepocranus fuscus in the south), the Malagasy dead-leaf-like Cladonotinae. Both species are endemic to small areas and are likely endangered because of deforestation. Both species most probably inhabit rainforest leaf litter.
Despite its relatively small area, Madagascar is one of the richest biodiversity hotspots on Earth, boasting a high number of endemic taxa from the species level and above. This fact characterizes Madagascar as a high-priority area for conservation (
The two members of the Valalyllini trib. nov. are similar but can be readily separated by several characters, namely the size and the shape of the eyes, the size of the leaf-like crest, and the general size of the body. Although these features can be variable individually, L. fuscus as a whole appears as a neotenic form of V. folium gen. et sp. nov. and is thus likely closely related to it but morphologically consistently separate. A remarkable similarity between the leaf-like tribes Valalyllini trib. nov. (Madagascar), Cladonotini (Asia), and Choriophyllini (Caribbean) is evident, so it is reasonable to hypothesize that those characters represent homologies and reflect the common ancestry on the ancient continent of Gondwana, which is a pattern that has been observed in numerous other taxa (
Both Lepocranus fuscus and Valalyllum folium gen. et sp. nov. are known only from a small area. A single digitalized specimen of L. fuscus is not exceptionally well preserved due to the presence of mould (
A new dead-leaf-like genus and species of Malagasy Tetrigidae, Valalyllum folium gen. et sp. nov. is described and compared to Lepocranus fuscus, the only species of the genus Lepocranus. The two species are similar, but clearly separable by the general size, the shape of the pronotal crest and the shape of the eyes. Valalyllum folium gen. et sp. nov. and Lepocranus fuscus are assigned to the newly described tribe Valalyllini trib. nov. as the only Malagasy tetrigids with leaf-like pronotal crests. The comparison of the present tribe with others of similar morphology has revealed several likely homologies, which imply common ancestry. As the taxonomy of Cladonotinae is not resolved yet, new groups within the subfamily are certainly going to be defined, which will help in elucidating their evolutionary relationships.
Lepocranus fuscus is already considered endangered according to the IUCN Red List and, following the same pattern, we propose that the new species should be considered endangered as well.
Both species from the newly described tribe are defined only by a single specimen each, which is a fact that obscures the variability of the species. However, considering the rampant deforestation of Madagascar and the fact that the species can be differentiated by intraspecifically invariable characters homologous with other leaf-like tribes, we find it vital to describe the new, likely endangered, species and thus assist the efforts to classify and protect the rich Malagasy biodiversity.
Thanks to Josef Tumbrinck (Germany) and Hendrik Devriese (Belgium), without them it would have been impossible to get all the literature. Many thanks to Mercedes París (Spain), Laure Desutter and Simon Poulain (France) for the help with specimens’ digitalization. Thank you to Barbara Anđelić (Croatia) for the help with photography and measurements. Thank you to anonymous and non-anonymous reviewers for their time and comments. This work was funded by Orthoptera Species File 2016 and 2017 grants to Josip Skejo and Josef Tumbrinck (“Digitalization of Tetrigidae types in European Musea”, and “Revision of Ignacio Bolívar’s Tetrigidae collection in MNCN”). Maks Deranja, Niko Kasalo, Karmela Adžić, and Josip Skejo are authors of equal contribution.