Arulenus miae Skejo & Caballero

Skejo, Josip & Caballero, Joy Honezza S., 2016, A hidden pygmy devil from the Philippines: Arulenus miae sp. nov. — a new species serendipitously discovered in an amateur Facebook post (Tetrigidae: Discotettiginae), Zootaxa 4067 (3), pp. 383-393 : 388-391

Species Arulenus miae Skejo & Caballero sp. nov.

( Figures 1 , 4 , distribution figure 5, habitat figure 6)

Material examined. (18 specimens): Holotypus: (1/18) 1♂ the Phillipines: Mindanao Isl.: Bukidnon Province X.2010. collector unknown det. J. Skejo, inventory number RMNH.INS 968003 (NCB-RMNH); Paratypus: (2/ 18) 1♂ the Phillipines: Mindanao Isl.: Bukidnon Province X.2010. collector unknown det. J. Skejo, inventory number RMNH.INS 968004 (NCB-RMNH); Additional material: (3–4/18) 2♂♂ the Phillipines: Mindanao Isl.: Bukidnon Province X.2010. collector unknown det. J. Skejo (available at lescoleopteres.com); (5/18) 1♀ (from Flickr) the Philippines: Bukidnon Province: rainforest area 800m asl [N8.252889, E125.038083] 24.IX.2013., photo: L. Garbielsen, det. J. Skejo; (6/18) 1♂ + (7–8/18) 2♀♀ E slopes of Kalatungan Mts. 1400–1600m asl [N7.94618653, E124.91472244] found on eBay det. J. Skejo, (9–11/18) 3♂♂+ (12–13/18) 2♀♀ Davao: Datu Sulumay Marilog district: Mt. Malambo 1 293m asl [N7.485417, E125.256583] 14.XI.2015. obs. & det. J.H.S. Caballero; (14–16/18) 3♂♂+ (17/18) 1♀ Davao: Datu Sulumay Marilog district: Mt. Malambo 1 250m asl [N7.485419, E125.256573] 14.XI.2015. obs. A. Mohagan, det. J. Skejo & J. H. S. Caballero; (18/18) 1♀ Bukidnon: Rainforest (without accurate locality) X.2013. leg. N. Layron, det. J. Skejo. All the georeferenced (localities with coordinates, altogether 4 of them [3 on the map] are shown in Figure 5 ., on the map).

Type locality. Philippines: Mindanao Isl.: Bukidnon Province

Type series depository. Holotype and paratype deposited in NCB-RMNH.

Species diagnosis. The species is similar to A. validispinus from which it can be separated by the following characters: (i) prozona slightly granulate, more or less smooth, (ii) metazona from 2.5/10 to 4/10 of pronotum length bearing one pair of spines, from 4/10 up to the end smooth and without tubercles, (iii) hind femora more slender (length/width ratio ~2.8–3:1) and with dorsal margin continuous and smooth.

Species description (characters for both males and females are presented, if there are any difference between the sexes, the difference is indicated)

General characters. Moderately large species (body size about 13 mm). Body smooth, finely granulated with very small and smooth tubercles. Apterous species. Coloration species-characteristic. General body color black. Antennae black. Head black to dark brown. The compound eyes in all the examined specimens yellow. Pronotum—black, dark brown in prozona, apices of the dorsal spines red. Internal lateral carina red. Fore and mid femora black, as well as fore and mid tibiae. Hind femora black to dark brown, with two tubercles on the distal transverse ridges yellowish. A tubercle on the dorsal carina of the hind femora yellow.

Head. Head in the level of pronotum. Fastigium of vertex in slightly indrawn from the level of compound eyes when looked from above, slightly convex when looked from front. Anterior margin of the fastigium of vertex narrow. Fossullae present, deep. Median carina of vertex present in the distant fourth of vertex length looked from the anterior pronotum margin, weak. Lateral carinae of the vertex absent or very weak and unnoticeable. Supraocular lobes absent. Vertex 2.2 times as wide as a compound eye. Median ocellus situated far below the compound eyes, between facial carinae on the place where they end. Lateral ocelli situated in the middle between the compound eyes. Frontal costa in lateral view not visible. Frontal costa bifurcation between the compound eyes, slightly above lateral ocelli. Scutellum narrow, facial carinae almost parallel, slightly divergent. Antennal grooves and scape considerably wider than scutellum, flagellum as wide as scutellum. Maxillary palpi flattened, black. Eyes in dorsal view ovoid, in lateral view round, in front view elliptic. The compound eyes not touching, but very close to the anterior margin of pronotum, occipital area very narrow. Antennal grooves situated parallel with the lower margins of the compound eyes. Antennae with 13 segments, 1st scape, 2nd pedicel, 3rd first flagellar segment, articles 4th to 8th cylindrical and filiform, 9th subapical segment slightly widened, foliaceous, half as wide as 10th, 10th subapical segment strongly widened and foliaceous, apical segments (11th–13th) reduced, filiform.

Pronotum. Pronotum flat (except two spines). Covering almost the entire abdomen, not covering abdominal apex and not surpassing hind femora. Anterior margin of the pronotum truncated. Median carina continuous, slightly elevated from the anterior margin to the apex. Mesozona of pronotum smooth. Protonal carinae present and slightly elevated. Extralateral carinae weak and unrecognizable. Interhumeral carinae strongly projected, forming two high spines. Spines are positioned on a very elevated part of pronotal discus and is only part where pronotum is not flat, but tuberculo-elevated and spined Humeroapical carinae forming with external lateral carinae obtuse, rounded angle. Interscapular area narrow, running to the half of the hind femora length. Lateral area quite wide. Internal lateral carinae incurved near the pronotum apex. Pronotal apex bilobate, with small concavity. A single paranotal lateral lobe present, directed downwards, slightly outwards near the apices, apex bilobate with small concavity.

Legs. Dorsal margin of fore femora compressed, sometime slightly undulate, ventral margin with stronger undulation, having one tooth distally. Dorsal margin of mid femora undulate, ventral undulate with a tooth in the middle paler than rest of femora. Dorsal external carina of fore and mid femora almost absent, visible only as slight elevation in mid femora, very week, ventral external absent in fore femora, visible as strong and elevated carina in mid femora. Dorsal margin of hind femora continuous, bearing small tubercle on half of its length. Fore and mid tibiae widened, rectangular in cross section. Distal tarsal segments of fore and mid legs considerably longer than proximal ones. Hind femora slender (2.8 times as long as wide). External median area with six transverse ridges, distal two ridges elevated more than others and pale colored. Genicular teeth smaller than antigenicular, but both teeth large and sharp. Hind tibiae black. First and third tarsal segments equal in length. Pulvili angular, but not acute spinose.

Female abdominal apex same as in A. validispinus . Male subgenital plate long and conical, black. Male cerci long as half of the subgenital plate, yellowish colored, slender and conical.

Etymology. The specific epithet is genitive case of the first Latin declension (a declension) derived from the name Mia, after M. Jurić, JS’s good friend—a student of the fashion and textile design at the Faculty of textile technology (Zagreb, Croatia).

Measurements. Males (N=7). Body length (from fastigium to the end of pronotum) = 8.95–11.98 mm; pronotum length = 9.55–10.89 mm; pronotum lobe width = 4.78–5.34 mm; pronotum height = 4.13–4.93 mm; fore femur length = 3.21–3.44 mm; fore femur width = 0.52–0.73 mm; mid femur length = 3.01–3.34 mm; mid femur width = 0.69–0.76 mm; hind femur length = 6.59–7.09 mm; hind femur width = 2.33–2.63 mm; vertex width = 1.21–1.29 mm; compound eye width = 0.49–0.57 mm. Females (N=5). Body length (from fastigium to the end of pronotum) = 9.81–12.33 mm; pronotum length = 9.88–12.01 mm; pronotum lobe width = 4.91–5.98 mm; pronotum height = 4.46–5.31 mm; fore femur length = 3.34–3.80 mm; fore femur width = 0.60–0.81 mm; mid femur length = 3.12–3.55 mm; mid femur width = 0.72–0.81 mm; hind femur length = 6.99–7.34 mm; hind femur width = 2.50–2.78 mm; vertex width = 1.24–1.36 mm; compound eye width = 0.52–0.63 mm.

Variability. Variability of A. miae Skejo & Caballero sp. nov. can be noted on three characters—1) pronotal length that varies from extremely short in some females, leaving last four abdominal sternites visible, to really long in some males, even a little bit extending over abdomen, 2) coloration that can vary from completely black (rarely) to black with only some pronotal carinae being red or orange or black with brightly colored carinae and pronotal spines (which are in fact just interhumeral carinae), 3) size of tubercles that are forming interhumeral spines, from very small to very large and 4) size and direction of interhumeral spines, usually being longer and directed dorsolaterad in females, while narrower and directed more dorsad in males.

Distribution. Known only from central Mindanao island’s mountainous rainforest area (700–1500 m asl), from regions Bukidnon and Davao.

Ecology and habitat. Here we describe the habitat of A. miae Skejo & Caballero sp. nov. in Mt. Malambo (Davao) ( Figure 6 A—mountain and 6B—habitat) and in surrounding of the Dila river (Bukidnon). Since those two localities are rather similar, we will generalize species habitat and ecology. Although little is known about other localities where the species was found, according to consulted maps, there are a lot of suitable rainforest mountainous habitats all along Bukidnon and Davao districts.

The species inhabits high elevation (700–1500m asl) tropical montane rainforests. The species is active both in rainy and in dry season. It is however, important to mention, that in Bukidnon and Davao, discrepancies in rainy and dry season are not as great as in e.g. N Luzon, Carga region of Mindanao, so it is reasonable to assume that the species is probably active throughout the year, despite our records which originated from mid September to late November (also early December). The temperature in areas where the species occurs ranges mostly from 22°C to 28°C. The area is dominated by trees and dense vegetation of grasses, ferns and shrubs. Vegetation type of such a forest is tropical montane rainforest, that is rich in ground vegetation (ferns, grasses, bushes, shrubs, low trees) and canopy epiphytes (mosses, ferns, lichens, orchids). In such a forest, no plant species predominates, but Ficus sp., Musa sapientum, Discksonia sp. and Medinilia magnifica are all present in similar relative abundance. The forest is very rich in mosses and lichens, as well as in detritus, which the species feeds on. It can climb shrubs and lower trees in search for mosses. With its cryptic coloration, it is well camouflaged to surrounding rotting leaf-litter, detritus and bark and is usually difficult to observe. Humid tropical rainforest is a suitable habitat for not only this but also some other Tetrigidae , for example Hirrius punctatus ( Stål, 1877) , Hymenotes sp., Discotettix scabridus ( Stål, 1877) , Mazzaredia sp. and Cleostratus sp.

Figures

FIGURE 5. Distribution of A. miae Skejo & Caballero sp. nov. generated from available georeferenced localities (see Material examined section).

FIGURE 6. Habitat of A. miae Skejo & Caballero sp. nov. A) view on Mt. Malambo (about 1 350 m asl), B) habitat of the species in montane rainforest on Mt. Malambo, photo: JHSC.

FIGURE 1. A. miae Skejo & Caballero sp. nov., the very first live female photo of the species taken by Leif Gabrielsen, and posted on Facebook ' Orthoptera' webpage.

FIGURE 4. A. miae Skejo & Caballero sp. nov., holotype. Photo credit: Frédéric Lécossois.