Meenoplus skotinophilus Hoch & López, 2025

Hoch, Hannelore, López, Heriberto, Naranjo, Manuel, Aguín-Pombo, Dora & Oromí, Pedro, 2025, Endless forms most wonderful: Four new cavernicolous planthopper species (Hemiptera, Fulgoromorpha, Cixiidae and Meenoplidae) from the Canary Islands, Subterranean Biology 51, pp. 61-101 : 61-101

Meenoplus skotinophilus Hoch & López sp. nov.

Figs 11 A, B , 12 A, B , 13 A – G , 14 A, B

Material examined.

Holotype: Spain • male; Canary Islands, El Hierro, Cueva de Guinea ; 27.77448369, - 17.99866804; 22 Mar. 2021; H. López and C. Andújar leg. ( IPNA) . Paratypes: Spain • 2 males, 10 females; same data as holotype; (1 ♂ 50356 DZUL; 3 ♀ 50357, 50358, 50359 DZUL; 1 ♂ 7 ♀ IPNA) .

Additional material.

Spain • 14 nymphs IV instar, 5 nymphs V instar; same data as holotype; (16 nymphs DZUL; 3 nymphs ( IPNA: BC 1267 , BC 1268 ; BC 1269 )) .

Diagnosis.

Meenoplus skotinophilus is similar in general appearance and degree of troglomorphy to Meenoplus claustrophilus from La Palma, but differs from this species by the distally stronger reduced tegmina and lighter overall pigmentation. From the other two cavernicolous Meenoplus species on El Hierro ( M. cancavus und M. charon ), it differs distinctly by its degree of troglomorphy (compound eyes present, tegmina and wings well developed, tegmina surpassing tip of abdomen). While the general configuration of the male and female genitalia is similar in all four species ( M. claustrophilus , M. skotinophilus , M. cancavus und M. charon ), Meenoplus skotinophilus differs from these by the following characters of the male genitalia: ventrocaudal lobes of anal segment with median tips subacute and well separated (vs rounded and nearly apposed in the other species), aedeagus with apical margins of phallotreme angulate (vs rounded in the other species), and of the female genitalia: ventral valvulae distally with a beak-shaped, sturdy and acute tip pointing mediad (vs bearing a minute tip), and with proximal portion broadly lobate and finely serrate (vs rounded and smooth in the other species).

Description.

Habitus. Troglomorphies weakly defined except for compound eyes and pigmentation, tegmina and wings well developed, in repose surpassing the tip of the abdomen. In general appearance, intermediate between epigean Meenoplidae and strongly troglomorphic species, such as e. g., Meenoplus cancavus Remane & Hoch, 1988 and M. charon Hoch & Asche, 1993 .

Body length. Male 2.8–2.9 mm (n = 3). Female 3.2–3.5 mm (n = 6).

Colouration. Head, pro- and mesonotum as well as male and female genitalia yellowish-brown, otherwise thorax und pregenital abdomen white. Compound eyes red. Tegmina translucent, pale stramineous in males, light brown in females; venation as well as areas along veins and between sensory pits yellowish-brown. Wings hyaline, venation yellowish-brown. Legs stramineous, apical spines of tibia and tarsal joints I – II, light brown.

Head. Vertex very short, ca. 12 times wider than medially long, distinctly separated from frons by a ridged transverse carina. Frons strongly convex, anterior portion bulbous, about as wide as medially high, at and below level of antennae with a short row of small and hardly visible sensory pits irregular in number (4–6). Lateral carinae of frons foliately ridged and directed anterolaterad, anteriorly with a distinct row of large sensory pits; lateral lamelliform carinae continuing onto postclypeus. Frons smooth, without median carina, postclypeus shallowly, anteclypeus steeply vaulted. Compound eyes small, lateral ocelli vestigial, median frontal ocellus strongly reduced, ist former position marked by a light circular spot at the lower portion of the frontal bulbous area. Scape short, ring-like, pedicel cylindrical, ca. 1.7 times longer than wide.

Thorax. Pronotum medially about 3.5 times the length of vertex, posterior margin obtusely angulate; pronotum weakly tricarinate, median carina very feeble. Tegulae, tegmina and wings well developed; tegmina distally surpassing tip of abdomen with ca. 1 / 5 their total length. Tegmen with rows of sensory pits along the distal part of the costal vein, along ScP + R (+ Ma), RP (+ MA) and along PCu, A 1, and their common stem PCu + A 1 („ Y-vein “). Metatibiae laterally unarmed, with 8 apical teeth. First metatarsal joint with 7 apical teeth, second metatarsal joint with 6 apical teeth.

Male genitalia. Genital segment in lateral aspect ventrally ca. 3 times as long as dorsally. Anal segment distally produced into two ventrocaudal lobes which converge medially, their median tips subacute and well separated from each other. Genital styles slender, narrow throughout, apically rounded, gently curved dorsad. Aedeagus tubular, stout, with phallotrema apically and dorsocaudally exposed, apical margins dorsally bluntly angulate.

Female genitalia. Strongly reduced, ventral valvifers produced into a rounded lobe; ventral valvulae with distal portion „ bird-head-shaped “, i. e., caudally rounded and medially with an acute tip pointing mediad, and with proximal portion broadly lobate, with median margin straight and finely serrate, apposed.

Molecular identification. Mitochondrial COI barcode sequences of 635 pb were obtained for three individuals of Meenoplus skotinophilus (specimen codes BC 1267 , BC 1268 and BC 1269 ). These individuals have identical barcode sequences, so no interpopulation genetic divergence has been detected. Either in BOLD or GenBank, no matches with similarity values greater than 85 % were detected, so the genetic information that we supply is actually new for the genetic lineage of the group of species that may belong Meenoplus skotinophilus . The sequences were deposited in GenBank (accession numbers PQ 530856, PQ 530856 y PQ 530856), with the following base composition:

AATGAGCCAGATTAATAGGTATAACAAGAAGAATAATTATTCGAATTGAATTAATACAACCTGGTTCAATAATTAAAAATGATCAAATTTATAACTCAATTGTTACATCACATGCATTCATTATAATTTTTTTTTCAGTTATACCCATCCTAATCGGTGGATTTGGAAATTGACTTGTACCTCTAATGATTGGAGCACCTGATATAGCATTCCCACGAATAAACAATATAAGCTTCTGAATATTACCTCCATCACTAATACTATTAATTTTCAGTTCATTTTCAGGTTCAGGTACAGGTACAGGATGAACAATTTATCCACCATTATCAAGAATTCCTGCACATTCTGGCCCATCTACTGACTTATCTATCTTTTCCCTTCATATAGCAGGTGTAAGATCAATTCTAGGAGCAATTAATTTCATTTCAACTATTATTAATATACGACCTAAAATAATAACAATAGAAAAAATACCCCTATTTTGCTGATCAATTTTCATTACAGCAATTTTACTTCTTCTATCATTACCTATTCTTGCAGGAGCAATTACTATACTATTAACTGATCGAAACTTTAATACATCATTTTTTGATCCAACAGGAGGAGGAGACCCTATTTTATATCAACATTTATTT

Etymology.

The species epithet is an adjective in nominative singular and a combination of the Greek words „ skótos “ (= darkness) and „ phílos “ (= friend). The gender is masculine.

Distribution.

The species is kown only from the type locality, Cueva de Guinea, municipality of Frontera (Fig. 1 ). Endemic to El Hierro.

Ecology and behaviour.

Meenoplus skotinophilus has been discovered in a lowland area of Frontera with a wide lava flow seemingly originating from the base of Tibataje cliff and extending towards the sea. The point from which the lava flow emerged is apparently clear, but no volcanic cone can be seen there, probably being buried under abundant sediment dragged from the cliff. In the upper part of the lava flow, close to the cliff, there is a complex of lava tubes, mostly unconnected but clearly formed during this eruption. One of them is Cueva de Guinea, a hardly 25 m long lava tube with a small entrance on the roof. At first the floor is rocky with scattered stones fallen from the ceiling, while in the last wider room clayish sediments cover the original substrate. The humidity is high and there are many roots attached to the walls and hanging from the ceiling. All this creates a good environment for the establishment of a community of invertebrates with some troglobitic species, like blind weevils and spiders, actually under study, besides a rich population of Meenoplus skotinophilus n. sp. around the roots. Also, American cockroaches ( Periplaneta americana ) were observed, both living specimens and remains. Outside the cave the vegetation is typical of dry areas and lava flows at low altitudes, where Euphorbia lamarckii Sweet , Schizogyne sericeae (L. f.) DC. and Rumex lunaria L. predominate.

Ecological classification. Meenoplus skotinophilus displays several troglomorphic characters, such as small compound eyes, reduced ocelli, and light, yellowish-white body coloration. Tegmina are reduced distally, but wings are well developed. Although there are no observations on the behaviour of the species, we assume that individuals may be able to perceive some visual input, and may have retained the ability of some, even if not sustained flight. According to the degree of troglomorphy, we assume that Meenoplus skotinophilus is restricted to subterranean environments, and we therefore regard it preliminarily as an obligate cavernicole or troglobiont, but of the hypogeomorphic type.

Conservation status.

The area surrounding the cave entrance is part of an archaeological complex transformed into an open-air ecomuseum, which features reconstructed homes of the island’s earliest inhabitants as well as those of later colonizers. The site also includes a center for the rehabilitation of an endangered endemic giant lizard and a natural cave that has been adapted for tourist visits. The volume of visitors is significant, and all facilities are equipped with bathrooms without connection to a sewage system, the wastewater being discharged directly into underground wells. This practice gradually contaminates the underground environment, promoting the colonization of invasive species such as Periplaneta americana in both Cueva de Guinea and the nearby showcave. The deterioration of the subterranean environment poses a potential threat to native subterranean fauna, which may either be displaced by invasive species or find their habitat unsuitable for survival. However, in the only sampling conducted in Cueva de Guinea Meenoplus skotinophilus was found abundantly, apparently with no serious threats at that time. To accurately apply the IUCN evaluation criteria to this species, it is essential to monitor its population in the short- to medium-term to determine whether it is indeed declining due to the aforementioned threats. However, M. skotinophilus should be included in the Vulnerable category based on IUCN criterion D 2. In this case this is well justified given the intense tourist activity in the location where the only known population of this new species is found, being expected a strong negative pressure on its conservation in the short-medium term.

Remarks.

Some nymphs of this new species have been selected for an ongoing genetic study with the aim of understanding the phylogenetic relationships between the three endemic species of Meenoplus present in El Hierro. This is a striking situation since it implies multiple speciation in the subterranean environment of a geologically very young island (1.12 Ma) in contrast to the absence of this genus on more mature islands rich in underground environments, such as Tenerife.

Figures

Figure 1. The Canary Islands and distribution of the new species described. Black triangle: Cixius palmirandus Hoch & Naranjo, sp. nov.; Black circle: Tachycixius gomerobscurus Hoch & Oromí, sp. nov.; Black stars: Cixius theseus Hoch & Aguín-Pombo, sp. nov.; Black square: Meenoplus skotinophilus Hoch & López, sp. nov. (https://commons.wikimedia.org/wiki/File:Map_of_the_Canary_Islands.svg; https://catalogo.idecanarias.es/geonetwork/srv/spa/catalog.search#/metadata/spagrafcan_MTLWMS_20160101).

Figure 11. Meenoplus skotinophilus Hoch & López, sp. nov. A head and thorax, dorsal aspect B head, ventral aspect. Scale bar: 0.5 mm.

Figure 12. Meenoplus skotinophilus Hoch & López, sp. nov. A tegmen B wing. Scale bar: 0.5 mm.

Figure 13. Meenoplus skotinophilus Hoch & López, sp. nov. Male genitalia A genital segment, caudal aspect B anal segment dorsal aspect C same, caudal aspect D left genital style, ventral aspect E anal segment, genital segment, aedeagus, genital style, in situ, left lateral aspect F aedeagus, ventral aspect G aedeagus, caudal aspect, view on phallotreme. Scale bar: 0.1 mm.

Figure 14. Meenoplus skotinophilus Hoch & López, sp. nov. Female genitalia A left lateral aspect B caudal aspect. Scale bar: 0.1 mm.