Cactisma, Molero-Baltanás & Zúñiga-Reinoso & Gaju-Ricart & Predel, 2025

Molero-Baltanás, Rafael, Zúñiga-Reinoso, Álvaro, Gaju-Ricart, Miquel & Predel, Reinhard, 2025, Morphological and molecular revision of the subfamily Heterolepismatinae (Zygentoma, Lepismatidae), with descriptions of two new genera from the Atacama Desert, Chile, ZooKeys 1260, pp. 233-278 : 233-278

Cactisma gen. nov.

Type species.

Cactisma camanchaca sp. nov.

Diagnosis.

Medium-sized silverfish (adults reaching 6.5–8.5 mm). Body shape slender, fusiform. Antennae as long or slightly shorter than body; caudal filaments almost as long as body length. Epidermal pigment scarce, dorsal scales pigmented. Scales covering the body dorsally and ventrally (including coxae) rounded to oval, orbicular, with more or less developed process surrounding sockets, multi-radiate and of diverse sizes. Scales absent on clypeus, labrum, antennae, maxillary and labial palps, abdominal styli, ovipositor, and caudal filaments. Scales of femora and tibiae with modified shape; smaller, subtriangular, narrow, with apical margin truncate or bifid, with a median indentation. Macrochaetae smooth, apically bifurcate. Compound eyes with 12 ommatidia, sometimes only 10 or 11 ommatidia developed. Frontal chaetotaxy concentrated on lateral parts, with a wide gap in the middle showing only one row of setae. Clypeus almost vertical, with a continuous transverse field of macrochaetae. Labrum with several irregularly arranged bifid setae. Antennae with trichobothria and also with chaetic, trichoid, and basiconic sensilla. Maxillary palps with the apical article bearing two or three styloconic sensilla, several basiconic sensilla type B and a single basiconic sensillum type C. Apical article of the labial palp with five papillae arranged in an oval shape, outer lateral part with several basiconic sensilla type B and a single basiconic sensillum type C. Anterior margin of pronotum with setal collar. Lateral margins of thoracic nota with several macrochaetae, most of them isolated, in some places forming a small comb of two macrochaetae; there are 1 + 1 posterior combs of two macrochaetae in a very lateral position, leaving the posterior margin bare. Trichobothrial areas open (Type 1 according to Mendes’ classification). Thoracic sternites parabolic, with convex or slightly truncated hind margins. Coxae with rows of macrochaetae on their anterior margin that are arranged in indistinct combs; the posterior margins with a single row of few long and thin macrochaetae. Tarsi consisting of four articles; pretarsus with two smooth claws and a medial empodial claw. Urotergites I-VIII with 3 + 3 combs of macrochaetae; the submedian combs sometimes consisting of only one macrochaeta. Urotergite IX without setae. Urotergite X short trapezoidal, with straight hind margin, several setae on its lateral margins and posterolateral edges; lacking clear combs. Urosternite I devoid of setae. Urosternites II-VII with 1 + 1 single macrochaetae; coxite VIII of females with one or two macrochaetae. One pair of abdominal styli. Females with a slender ovipositor of the primary type. Male unknown.

Remarks.

This new genus is different to Lapidisma gen. nov. from Chile and to the other genera of Heterolepismatinae by the characters listed in Tables 2 , 3 . It is clearly different to Australian Heterolepisma due to the presence of bifid macrochaetae on labrum (only small acute setae in Australian taxa), the absence of posterior combs of thoracic nota (present in Australian species), shorter urotergite X and different shape of scales covering appendages; to Maritisma due to the same differences except for the shape of urotergite X, and additional characters such as the different urosternal chaetotaxy and labial palp characters. Cactisma gen. nov. is different to Vistrolepisma (previously Visma ) because of the absence of posterior combs on thoracic nota, different shape of thoracic sternites (widely truncate in Vistrolepisma ), shorter urotergite X and lower number of abdominal styli. Differences to Lapidisma gen. nov. include different shape of scales of appendages, lower number of macrochaetae on infralateral urotergal combs, and lower number of pairs of styli. Problems arise when comparing Cactisma gen. nov. with some incompletely described species of Heterolepisma from regions other than Australia, as information on distribution and shape of scales on appendages or chaetotaxy of labrum is missing. Considering the characters available, Cactisma gen. nov. is different to other previously described species assigned to Heterolepisma due to the absence of macrochaetae on the hind margin of thoracic nota and shorter urotergite X. Apart from Lapidisma gen. nov. (and H. annectens , now assigned to Lapidisma ), the only species sharing both characters, are the Heterolepisma described from Argentina, i. e., H. andinum and the type species of the genus, H. pampeanum . A specimen assigned to H. andinum was available for our study and differences concerning the shape of scales in appendages (lanceolate scales in legs, for example) and the frontal chaetotaxy indicate that the Argentine species indeed belong to a different genus, so Heterolepisma s. str. corresponds only to Argentine species (and, perhaps, to other species of this genus described from other geographic areas, but not from Chile so far); see Tables 4 , 5 , and additional comments in the Discussion section.

Etymology.

This generic name is a fusion of the words ‘ cactus’ and ‘ lepisma’, the latter used for most genera of Lepismatidae . Cactus derives through Latin from the ancient Greek word κάκτος used for an indetermined spiny plant and currently used for designating plants belonging to the family Cactaceae ; decaying specimens of these plants provide the habitat where this new silverfish has been found. The grammatical gender of this genus is neuter.