Tasmantrix Gibbs
Creators: name: Gibbs, George W.
Publisher: name: Zenodo
Year: 2010
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Lepidoptera
Micropterigidae
Tasmantrix

description: Tasmantrix Gibbs, gen. nov.
Type species: Palaeomicra calliplaca Meyrick, 1902, by present designation.
Note. The recent unpublished phylogeny of the entire family Micropterigidae (Gibbs et al. 2004), using the 16S rRNA gene, shows the ‘Australian group’ of taxa split into two well-supported subclades (Fig 16): one incorporating seven conservative east Australian species in the genus Tasmantrix designated here; the other with four species exhibiting considerable phenetic diversity. In this revision, the latter are subdivided into three genera, Zealandopterix Gibbs (1 species), Aureopterix Gibbs (2 species) and Nannopterix Gibbs (1 species), together spanning north Queensland, New Caledonia, and New Zealand.
Diagnosis. Restricted to eastern Australia. Forewings dark grey to black with strong purple or bronzy iridescence and shining white fascia (Figs. 1 A–G); phallus apex normally concealed within a densely scaled phallocrypt; gonopore terminal, bordered by uniform radial folds, crescentic, like the partly gaping mouth of a fish (e.g. Fig. 10 C&D) (‘fish-mouthed’).
Description. Head interocular index 0.7 to 1.0 in male, 0.8 in female. Ocelli present. Vertex between ocellus and compound eye microtrichiated but lacking piliform scales. Antennal scape about twice the length and width of the first flagellomere, barrel-shaped, with a shallow indentation at mid-length, but not markedly dumb-bell-shaped; ratios of scape:pedicel:first flagellomere are length = 2:1.1:1 and width = 2.2:1.7:1; scape and pedicel with tufts of moderately long piliform scales extending to beyond the first flagellomere. Flagellum of male with 39–54 flagellomeres, clothed with lamellar scales on basal 1–4 flagellomeres; female with 28–40 flagellomeres, the basal 6–11 scale-covered; female antenna always considerably shorter than male. Flagellomeres moniliform (shuttle-cock shaped, Fig 5 E) or sub-moniliform (Fig 5 C) but filiform (barrel-shaped) in one species. Antennal ascoid morphology (Fig. 5 C, E, F) unique within the Micropterigidae, a synapomorphy of the four new genera defined here comprising the ‘Australian-group’ lineage; a comb-like basal element orientated around the circumference of the flagellomere and bearing a row of curved sensory branches, the whole ascoid normally arising from a transverse groove around the flagellomere, more or less in its middle region; each ascoid (two opposing ascoids per flagellomere) subtending 5–11 sensory branches; surface of flagellomeres with a reticulate pattern of fine sculptural ridges; the entire flagellomere densely overlain by whorls of long narrow fluted scales that reach toward the following flagellomere, obscuring the underlying features. Mandibles robust, asymmetrically toothed with 3 large apical teeth on right mandible; smaller close-set teeth over inner surface grading down to a dense hairmass at proximal inner angle. Labial palps 3-segmented. Maxillary palps 5-segmented; 1.1–1.7x head width; ratio about 1:0.9:1.5:2.2.3:0.7; palp segment 4 almost straight, with fine transverse striations. Head vestiture comprising dense tufts of moderately long piliform scales.
Tegulae usually with combination of both lamellar scales (along outer margin) and moderately long piliform scales, but varies from a totally lamellar vestiture (tasmaniensis) to one where lamellar scales are minimal (thula); mesoscutum with lamellar scales; metascutum naked apart from some scattered long piliform scales posteriorly. Foretibial epiphysis well developed.
Forewing (Fig 4 C) with both Sc and R1 forked; sc-r crossvein either absent or present as a faint trace; R S veins stalked, R S4 posterior to apex. Hindwing with humeral vein absent, or vestigial; R1 not present as an independent vein; the Sc+R1 vein forked; sc-r crossvein present or absent; a single A vein (A1?) reaching to the margin; 2–3 frenular bristles.
Male abdomen and genitalia. Dorsum A1 largely membranous, with few scales; in some species a narrow trace of a transverse sclerite is present. Abdomen unspecialised with typical proportions, about 3x longer than deep; abdominal tergites and sternites unmodified, apart from a slight reduction of T 8 in some species. Segment 5 gland present; a typical protuberance of southern sabatincoid form (Kristensen & Nielsen, 1979) in males of tasmaniensis – a raised cylinder which bears a cluster of very long piliform scales, arising from near the perimeter of the protuberance, with a scale-like portion of integument around the aperture – but uniquely sexually dimorphic in the remaining 6 species, where the external male gland takes the form of a flattened lobe (Figs. 6 E, F) or raised mound of specialised integument on the posterior margin of S5, lacking long piliform scales but with a scale-like pattern of grooves radiating from the gland orifice.
The sternal sclerotisation of segment 8 appears as a pair of small remnants in five species of Tasmantrix, discrete in calliplaca and fragilis, and fused to the anterolateral margins of segment 9 sclerite in lunaris, nigrocornis, phalaris and tasmaniensis. Segment 9 sclerite relatively short in Tasmantrix, averaging less than 1.2x length of S 6 in ventral mid-line. Its form varies from a substantial complete ring in tasmaniensis, to a much-reduced partial ring which remains ‘open’ dorsally. The anterolateral concave margin of sclerite 9 is usually moderately thickened. Valvae simple in all but two species where each is divided into an upper and lower arm; inner face slightly concave, bearing conspicuous setae which are inclined anteriorly (herein referred to as retro-setae); median plate with a short thickened stem arising from the mid-ventral junction of the valves, extending forward as a thin, laterally expanded, apodemal fan. Tergum 10 extremely variable, ranging from a simple median lobe, to a broad, hood-like structure with a slightly emarginate posterior edge, to two separate lobes; upper surface densely scaled and setose, lower surface lacking setae or with a mound of specialised setae on its lateral margins. Anal cone prominent, densely microtrichiated and usually strengthened by a pair of lateral melanized sclerites, with or without setae, separate from T10. Phallus relatively short, from 1.8–2.5x length of S6. Distal part of phallus approximately the same length as phallobase, a thin-walled apical ventral bulb discernable but never prominent, compressed laterally, but lacking a distinct keel; lappets generally absent, although vestigial lappets occur in lunaris; gonopore terminal, crescent-shaped, due to extension of dorsal and ventral lips in the mid-line, resembling the gaping jaws of a fish (‘fish-mouthed’), bordered by numerous equal-sized radial folds. In many preparations a small eversible bladder was noted projecting from the gonopore; a tapering, conical sac, no longer than the diameter of phallus. It possibly represents an eversible distal portion of the ejaculatory duct. Phallocrypt densely clothed with large, acutely pointed micro-scales.
Female abdomen and genitalia. Abdomen about 2.7x longer than deep in female; S5 gland present; exit area protuberance of typical southern sabatincoid form (Kristensen & Nielsen, 1979) in all known females (Fig. 6 D). Segment 8 unmodified. Segment 9 largely membraneous, with the 9th sclerite only very weakly developed and forming a narrow or incomplete ring towards the posterior of the segment; scattered macrosetae present on both membraneous and sclerotised areas, concentrated into an ordered band around posterior margin of the sclerite. Segment 10 lateral sclerites (‘terminal papillae’) roughly semicircular; or if rectangular with rounded corners, orientated vertically; bearing uniformly scattered macrosetae. Genital chamber with a well-developed, heavily-staining, eversible ‘spermathecal papilla’ on its dorsal side enclosing the thickened basal duct of the spermatheca when retracted and supporting the entrance to the corpus bursae ventrally; cup-shaped, with the spermatheca entering through a circular or pear-shaped diaphragm orientated antero-dorsally, sometimes with thickened ventral or lateral flanges around the opening to the bursa. Spermatheca of 3 zones; a short proximal, heavily thickened basal duct, a little longer than the retracted papilla; an elongate, very thin-walled, parallel-sided utriculus, about 3x longer than duct; a short, narrower, more densely-staining loculate lagena, about the same length as duct, terminating in a short terminal filament; whole spermatheca lacking distinct constrictions or swollen regions. Corpus bursae small, simple, without sclerotisations or spines in its walls.
Larva. Larvae attributed to a species of Tasmantrix have been discovered 15 km SE of Nimmitabel (L. Hill, Jun 1985), New South Wales, Australia. Species identification cannot be confirmed because no adult micropterigids have been found at that locality, although both T. nigrocornis and T. lunaris are known to occur within the geographic region. Larval specimens were heat extracted from “swamp litter, moss, tussocks, sods etc at 1060 m. (however, the exact source of this sample is uncertain).
These larvae are of the Micropterix morphotype (Figs. 7 G & H). They comply with the groundplan character matrix for the family (Davis 1987) but differ from the hexagonal sabatincoid type by their crosssectional shape, being more or less circular at mid-length; with seven pairs of abdominal spiracles; eight pairs of abdominal prolegs, and an unpigmented integument, with a honeycombed, finely papillated texture.
Head (Figs. 7 J, K) capable of being totally recessed into the prothorax. Cranial ecdysial lines indistinct or absent (even on mature larvae); stemmata absent; hypostomal bridge without an antero-median melanisation. Chaetotaxy dominated by macrosetae with the loss of a number of microsetae from around the stemmatal region, including A3, L1, SS2 and SS3; nor could the P group, the MG group or C1 be located on the specimens available (nomenclature according to Davis, 1987 and Hashimoto, 2001). The median M1 seta is between the antennal bases but because these are more posterior in comparison with the sabatincoid type of larvae, M1 and the pair of AF1 setae form a distinct triangle on the frontoclypeus (Fig 7 K).
Thoracic legs (Fig. 7 L) relatively long, four-segmented, and well-developed for a micropterigid, with a weakly melanised coxal sclerite; a thickened portion of the inner basal margin of femur possibly represents a trace of the trochanter fused to the base of the femur; femur with 3 long macrosetae; an elongate fused tibiotarsus with three small setae, two basally and one distal; a strong tarsal claw with a small seta at its base. Abdominal segments 1–8 with well-developed ‘prolegs’ with tapering conical base terminating in a rounded apex. Functional spiracles present on abdominal segments 1–7, situated in the middle of the segments and in a longitudinal line above seta L1. Setae of dorsal and lateral areas consistent throughout, sculptured with longitudinal ridges; thick and blunt tipped, of moderate length, parallel-sided. The more ventral setae are variable, often of normal acutely pointed type (Fig. 7 I).
Prothorax with 10 pairs of setae; five pairs on the dorsum, not aligned with integumental ridges but forming two slightly oblique rows, two in the dorsal row (D1 & D2); three forming an oblique line subdorsally, the most anterior (XD1) a slender seta on the head recess margin, XD2 and L1 thicker, blunt-tipped; two further lateral setae, aligned horizontally, away from the recess margin, with the anterior seta more acutely pointed; two SV setae below the level of the spiracle, in a more or less horizontal row, the anterior more slender and acute; a single mini-seta (MV1) on the recess margin close to the ventral mid-line. Mesothorax and metathorax with 8 pairs; the D and L setal groups forming a vertical row down the middle of the segments; 2 D setae, 3 L setae, 2 SV setae immediately above base of thoracic leg, in horizontal row.
Abdominal segments 1–7 with six pairs of setae; D1 and D2 equal; two L setae above spiracle, equal in length to D setae, with L2 immediately anterodorsal to the spiracle; two SV setae at some distance below spiracle, SV2 lateral to the ‘coxal’ area of the proleg is more slender and acute. On A8 the spiracle is absent: the D setae have taken up more-or less horizontal alignment: the L setae in oblique line with L2 more posterior; the SV setae as for previous segments. The terminal lobes of the trunk comprise A9 dorsally and A10 ventrally surrrounding the anus, A9 with two pairs of thickened setae, one aligned with the D-group, the other with L-group; A10 with three pairs of fine, acutely pointed macrosetae, two above the anus and one below.
Comparative remarks. When Edward Meyrick (1902) described the first micropterigid known from Australia as Palaeomicra calliplaca, he recognised its close affinity with P. zonodoxa, a species already recognised from northern New Zealand and went so far as to suggest that this and other examples provided “… a sufficiency of biological evidence to indicate a former land connection between Queensland and the northern extremity of New Zealand by way of New Caledonia …” This prophetic remark amounts to the first recognition of the ‘Australian-group’ as discussed in this revision. Faucheux (2004) has described the type of antennal ascoid sensilla in ‘ Sabatinca’ sterops (herein Aureopterix), recognising it as a defining character for “a distinctive ‘Australian’ species-group (note that this grouping excludes Austromartyria gen. nov.). This transverse linear form of ascoid is also found in Zealandopterix, Aureopterix and Nannopterix but, unfortunately, its phylogenetic significance cannot be resolved in the absence of satisfactory outgroup evidence. Virtually all the remaining morphological characters of this new genus are shared, in different combinations, across members of the entire family in both hemispheres. Notable among these is the uniquely sexually dimorphic form of the S5 gland protuberances and the variable retention of discrete S8 sclerites.
The presence of paired glands opening on abdominal S5 is considered an autapomorphy of the Amphiesmenoptera (Kristensen 1975). They occur across a number of primitive lepidopteran groups, but are lost in some lineages (e.g. Micropterix, Hypomartyria). Two distinct modifications of the external areas surrounding the glands occur in Micropterigidae but only in Tasmantrix do both types exist within the one genus and indeed within certain sexually dimorphic species. Males of 6 Tasmantrix species share the modification which lacks long piliform scales, opening on a specialised flange-like area or slightly raised protuberance (Figs. 7 C, E). This type is found in both sexes throughout the northern Pacific micropterigid lineage (including Epimartyria, Paramartyria, Neomicropterix, Palaeomicrodes, Vietomartyria and Issiomartyria) (Kristensen 1984b; Hashimoto & Mey 2000; Hashimoto 2006). In contrast, females of Tasmantrix (where they are known) and males of T. tasmaniensis possess the typically sabatincoid type of external gland, characteristic of Sabatinca s.str., Austromartyria gen. nov., Palaeomicra, Agrionympha, the undescribed afrotropical taxa and Squamicornia, in which a short cylindrical protrusion is equipped with a number of long piliform scales around the orifice (Figs. 7 D, G, H). Development of the gland protuberances is relatively consistent throughout all southern taxa which have the long scales but varies remarkably between the species with the naked glandular orifice. At one end of the latter series is T. fragilis sp. nov. with an external protrusion a mere 0.01 mm in diameter, while at the other is T. nigrocornis sp. nov. with an external lobe of 1.80 mm. The form of the gland exit structure suggests emission of a pheromone-like substance, possibly for aggregation at food sources (such as at dehiscing fern sporangia), but its precise function has yet to be researched.
Desclerotisation of the sternal area of segment 8 in male Micropterigidae has been interpreted as a groundplan apomorphy of the family, with a total lack of discrete venter 8 sclerites being characteristic of the sabatincoid group of genera (Kristensen & Nielsen 1979). However, apart from Micropterix, discrete sternum 8 remnants are now known in Tasmantrix, Aureopterix, Nannopterix, Agrionympha and two Malagasy taxa (Davis, Gibbs, Kristensen & Lees. in prep). In the light of this variable expression, it is interesting to find a series of conditions in Tasmantrix species ranging from fully discrete remnants of S8 sclerites in calliplaca, through what appears to be a fused S8+S9 sclerite, to a species with no trace of an S8 remnant, T. tasmaniensis.
The discovery of Tasmantrix larvae, which are clearly of the Micropterix morphotype, poses interesting questions in the quest for an overall micropterigid phylogeny, the key one being does this larval type represent the basal groundplan for the family? Many of the distinguishing features of this morphotype, viz the rounded, non-hexagonal body-form, the longer thoracic legs, well-developed abdominal prolegs, the reduction of stemmata and the lack of integumental pigment could be interpreted as common adaptations for a subterranean habitat. But other characters, such as the loss of the functional spiracle on A8, which is shared between these two genera, might suggest a more fundamental association. Ultimately, there will hopefully be a molecular resolution for this issue of the deeper lineage divergence within Micropterigidae, but at this time, where our only evidence comes from the 16S rRNA mitochondrial gene, the basal topology is not sufficiently robust to establish the nature of the relationship between Micropterix and Tasmantrix.
Etymology. The genus name highlights the geographic range of these species, bordering the Tasman Sea along the eastern coastal fringe of Australia. The suffix –trix is an onomatopoeic version of the ending of all Australian-group micropterigids based on the Palaearctic genus Micropterix.
description: Published as part of Gibbs, George W., 2010, establishment of five new genera from Australia, New Caledonia and New Zealand, pp. 1-48 in Zootaxa 2520 on pages 17-21, DOI: 10.5281/zenodo.196244