Notable plesiomorphies and notable specializations: Head structure of the primitive “tongue moth” Acanthopteroctetes unifascia (lepidoptera: Acanthopteroctetidae)

Abstract

The Acanthopteroctetidae are one of the first-originated family-group lineages within "tongue moths" (Lepidoptera-Glossata). The purpose of this study is to provide a comprehensive account (based on whole mount preparations, serial sections, and Scanning electron microscopy) of the cephalic structure of an adult exemplar of the family, to supplement the sparse available information. Notable plesiomorphies include the retention of frontal retractors of the narrow labrum, a high supraocular index linked to strong development of cranio-mandibular ad- and abductors, and perhaps the unusually short but still coilable (just ca. 1.5 turns) galeal "tongue." Notable specializations (probably mostly family autapomorphies) include a complement of large sensilla placodea on the male antennae, an apical attachment of the long dorsal tentorial arm to the cranium, an extreme reduction of the single-segmented labial palps, a particularly strong subgenal bridge and a surface structure of near-parallel ridges on the ommatidial corneae. The presence of sizable saccular mandibular (type 1) glands opening into the adductor apodeme is unexpected, no counterparts being known from neighboring taxa. The same is true for ventral salivarium dilator muscles originating on the prelabium; and tentatively suggested to be homologues of the extrinsic palp flexors (the insertion shift being related to loss of original function due to palp reduction), rather than to the ventral salivarium muscles of more basal insects. A complete "deutocerebral loop"' may or may not be developed, as is true for a mutual appression of the optic lobe and circumoesophageal connective/suboesophageal ganglion, enclosing the anterior tentorial arm between them; a suboesophageal innervation of the retrocerebral complex was not observed. No characters bearing on the monophyly of the Coelolepida were identified. The scapo-pedicellar articulation with a scapal process and a smooth intercalary sclerite is reminiscent of conditions in Neopseustidae, but remains debatable as a synapomorphy of the two families.

A molecular phylogeny for the oldest (nonditrysian) lineages of extant Lepidoptera, with implications for classification, comparative morphology and life‐history evolution

“…The transformation of the generalized galeae into the coilable proboscis/tongue initially took place with surprisingly little modification of the maxillary musculature (Kristensen, ; Krenn & Kristensen, ). In contrast, the physical properties of the proboscis wall (with cuticle elasticity enabling nonmuscle‐aided recoil), as well as details of its specialized surface configuration such as the linking mechanism (Krenn & Kristensen, ; Kristensen et al , ), have in eriocraniids, acanthopteroctetids and lophocoronids a remarkable similarity, which surely reflects the acquisition of these specializations in the stem lineage of Glossata (node 8). Loss of mandibular function in the postpharate adult stage, and associated reduction of mandibular sclerotization and loss of mandibular teeth and cranial articulation are additional glossatan ground plan autapomorphies associated with the reorganization of the feeding apparatus, and so is the loss of a prominent epistomal sulcus; in the maxillary palp, the flexor muscle between segments 2 and 3 is lost.…”

“…A few morphological specializations shared between Acanthopteroctetidae and Neopseustidae have, in fact, been found, mainly in the antenna: the smooth intercalary sclerotization and the alignment of antennal scale sockets in longitudinal rows. Also, the prominent peg‐and‐socket type of neopseustid scapo‐pedicellar articulation is to some degree approached in Acanthopteroctetes (Kristensen et al , ). The narrowed labrum, which is present in Acanthopteroctetes and Neopseustis Meyrick, can with some certainty be considered a parallelism, as the neopseustids Apoplania and Synempora Davis & Nielsen have the ancestral, broader and more pentagonal type, and, importantly, the overall generalized neopseustid Nematocentropus Hwang also has a broad labrum (Davis, ; Kristensen et al , ; N.P.…”

Catapterix tianshanica sp. n. – the second species of the genus from the Palaearctic Region (Lepidoptera, Acanthopteroctetidae)

“…Recent discoveries in South America (Kristensen et al 2013) and South Africa (Mey 2011) demonstrated that the genus and family have a much larger distribution on the globe, which is in agreement with the antiquity of the group that is certainly of Mesozoic age (Grimaldiand Engel 2005).…”

“…Nye and Fletcher (1991: p.xiv) included the family in Acanthopteroctetidae (without providing a formal synonymization however) and this view was followed by most subsequent authors (Nielsen and Kristensen 1996;Kristensen 1998;Kristensen et al 2007;Kristensen et al 2013).…”

Compound eyes of insects and crustaceans: Some examples that show there is still a lot of work left to be done

“…) as in Acanthopteroctetes sp. (Kristensen et al ., ) and the collembolan Tomocerus flavescens (Eisenbeis & Wichard, ).…”