FNZ 65 - Izatha (Insecta: Lepidoptera: Gelechioidea: Oecophoridae) - Methods and conventions
Hoare, RJB 2010. Izatha (Insecta: Lepidoptera: Gelechioidea: Oecophoridae). Fauna of New Zealand 65, 201 pages.
( ISSN 0111-5383 (print), ISSN 1179-7193 (online) ; no. 65. ISBN 978-0-478-34724-1 (print), ISBN 978-0-478-34725-8 (online) ). Published 02 Sep 2010
Methods and conventions
Many Izatha species have been collected at light after dark, a 125W mercury vapour bulb being highly effective. However, some species are rarely or never collected by this method, and are possibly largely diurnal in habit. This may account for the apparent rarity of species such as I. walkerae n. sp., which has been collected in a Malaise trap and in a car, and I. dasydisca n. sp., which has been taken at rest on a tree trunk and by sweeping. Searching tree trunks and fences, especially those with a covering of lichen, is another method by which Izatha species may be found, and many specimens were probably taken this way by the earlier collectors. Hudson collected I. caustopa on the trunks of Fuchsia trees from the dead branches of which they had recently emerged (Hudson 1928).
With larvae feeding in dead wood, better results have been obtained by keeping the substrate humid rather than allowing it to become too dry. However, it is better to collect wood containing larvae on a dry day to avoid excessive humidity and the attendant risk of mould. Adults have been reared by placing pieces of dead wood or twigs containing larvae in closed plastic containers on absorbent kitchen paper. Condensation should be wiped away when it forms on the inside of the container. Alternatively, a hole may be cut in the lid of the container and netting material fastened over the hole; the substrate must then be kept moist by regular spraying with water.
Moths collected for this study by the author were usually killed in ammonia and the wings spread on balsa-wood setting boards, using a ‘setting bristle’ to brace the wings as they were moved into position, and strips of tracing paper to hold them in place, following the method described, e.g., by Sokoloff (1980). To avoid flattening the scale-tufts on the forewings, the tracing paper can be pinned across only the terminal portion of the wings. Ammonia will quickly alter the green colour of members of the I. peroneanella complex, and adults of these species should preferably be placed in a freezer overnight or killed with another agent such as ethyl acetate.
Preparation of slides of genitalia followed the methods described by Hoare (2000) for Nepticulidae, except that a solution of 3% acid fuchsin in 70% ethanol was substituted for the acid fuchsin-azophloxin stain described there, and no lactophenol was used. The valvae of males were spread in the usual manner for microlepidoptera (e.g., Robinson 1976). Wing venation preparations followed the methods described by Common (1990). Larvae were killed in boiling water, and preserved and examined whole in 70% ethanol; pupal exuviae were examined either dry or immersed in glycerol.
Most specimens of Izatha in good condition can be identified to species by comparison with the colour figures provided here (Fig. 1–83). In cases of uncertainty, the identification can be checked by running the specimen through the key to adults (Key 1, p. 24), or by consulting the descriptions and diagnoses. Some species appear to lack external distinguishing characters (e.g., acmonias, lignyarcha, picarella); these can be determined on genitalia (using the illustrations or Key 2, p. 27), or, with caution, from locality, since records indicate they are allopatric. In the case of very worn or aberrant specimens, or those preserved in fluid, it may be necessary to dissect out the genitalia and (for males) identify using the key to genitalia (Key 2), or compare the dissection with the genitalia figures.
Conventions and terminology
Morphological terminology largely follows Common (1994, 1997, 2000), but the term ‘bulbus ejaculatorius’ is used here for the membranous structure connected to the outer wall of the phallus at or near its base (cf. Oiticica 1946), whilst the ductus ejaculatorius is the membranous tube that runs inside this into the phallus, and forms the primary gonopore at the point where it merges with the vesica (cf. Callahan 1958). Kristensen (2003) regards the intromittent organ in male Lepidoptera as a phallus rather than a true aedeagus; his terminology is followed here. Other terms that are novel or may cause confusion are explained below.
Juxto-costal plate. This term is coined here for the structure in the valva of the male genitalia running from the base of the lateral lobe of the juxta to the costa (Fig. 124). The same structure was termed the ‘basal costal process’ by Dugdale (1971: 133, description of I. oleariae), and was noted by Philpott (1927b: 103), who stated ‘it is probably a development of the editum, which in Borkhausenia [i.e. Tingena] and other related genera consists only of a slight fold clothed with a few short hairs.’ Philpott’s ‘editum’ is here termed the pulvinus, following Common (1994: fig. 13). Since the pulvinus is often well-developed and distinct from the juxto-costal plate in Izatha, I disagree with Philpott’s interpretation, and regard the plate as probably homologous with the ‘fusiform appendages’ described by Common (2000: 14) for the Barea group of Oecophoridae. The ‘fusiform appendages’ run between the juxta and the pulvinus, as does the juxto-costal plate. Because the plate is rarely fusiform, and because it is dubiously homologous with the basal costal process in other genera, I have coined a neutral term for the structure. The juxto-costal plate is also present in Gymnobathra Meyrick s.s. (see below for restricted definition of Gymnobathra), but not in Hierodoris.
Phallus: lobes. Most species of Izatha have the apex of the phallus divided more or less distinctly into 3 sclerotised lobes (Fig. 126). The arrangement of these lobes does not appear to be constant in the genus, i.e., they are presumed to rotate during the course of evolution with respect to the base of the phallus. Since the degree of sclerotisation and number of teeth borne by each lobe also varies considerably, it is very difficult to assess the homology of the lobes across the different species and adopt a consistent nomenclature. Therefore, the lobes have been described ‘naïvely’ for each species, as observed in slide preparations with the ventral surface of the phallus uppermost, and no assumption should be made, e.g., that the ‘left lobe’ of one species is homologous with the ‘left lobe’ of another. Further careful comparative work will be needed to establish these homologies.
Phallus / vesica: spines and teeth. The terms ‘spine’ and ‘spinule’ are here used for narrow-based pointed processes, whilst ‘teeth’ are broad-based pointed processes, often hook-like (i.e., asymmetrical). Most of the small exterior processes on the phallus in Izatha can be regarded as teeth on this definition. The direction of the asymmetrical teeth is described with the phallus apex pointing upwards (as in most slide preparations), i.e., ‘backward-pointing teeth’ are those with tips directed back towards the phallus base. The vesica of many species bears rows of translucent spinules (Fig. 127), which may be mechanoreceptive sensilla.
Vesica: compound cornutus. This term is coined here for a structure present only in the attactella-group (Fig. 130, 132) and in Izatha convulsella (Fig. 199), and consisting of a number of closely associated small leaf-like or spine-like fixed cornuti. The structure resembles the group of overlapping cornuti described for Hierodoris electrica (Meyrick), H. s-fractum Hoare, and H. pachystegiae Hoare by Hoare (2005). There is 1 compound cornutus in Izatha attactella and I. convulsella, and 2 in I. blepharidota and I. voluptuosa. The structure in convulsella is different to that in the attactella-group and may not be homologous.
Vesica: fishhook cornutus. This is a blade-like fixed cornutus in the vesica, typically with a strongly curved and robust base (Fig. 125–127). Often the apex is very fine and poorly sclerotised, terminating in a tiny bead-like tip. It is positioned towards the apex of the phallus, i.e., near the base of the everted vesica.
Vesica: deciduous cornuti. These cornuti (Fig. 126) are present only in the balanophora-group. They number from 3 to possibly 48 in the various species, and are usually blade-like with buttressed bases; they are associated with a similar number of disc-like pores (Fig. 127) in the vesica wall. These cornuti become detached during copulation and are released in the female genital tract, where they are often found on dissection. Intriguingly, the cornuti are never found closely approximated to the pores in KOH-treated specimens, and indeed the pores appear to be too small and closely packed to represent sockets in the strict sense, since the buttressed bases of the cornuti seem much too large to fit directly against them, even allowing for some overlap of the ‘buttresses’. Since there is always one pore per cornutus, there must be some form of connection, and it is presumed that some intervening structure, destroyed by KOH, exists. In some slide preparations, the Chlorazol Black stain shows up what appears to be an indistinct mushroom-shaped vesicle emerging from the outer side of each pore into the lumen between the vesica and the phallus wall (Fig. 128). Unless an artefact of staining, these vesicles seem likely to have some function related to the detachment of the cornuti. Such structures do not seem to have been reported previously in Lepidoptera, and they require further investigation.
Female genitalia: S8. In most Izatha species, the ostium is margined anteriorly by a narrow sclerotised strip, often strongly curved, here called the lamella antevaginalis. The posterior sclerotised portion of the segment is simply termed ‘S8’; this usually has a broad anterior evagination of the same width as the ostium. The anterolateral arms of S8 are often somewhat recurved and concave where they meet the lamella antevaginalis, forming what are here termed the ‘scoop-like lateral flanges’ (Fig. 129). The term ‘lamella postvaginalis’ is reserved for sclerotisation of S8 separate from this posterior sclerotised portion, and immediately adjacent to the ostium; such sclerotisation is only known in the oleariae-group.
Female genitalia: antrum / ductus bursae / corpus bursae. The antrum is here defined as the section of the female genital tract from the ostium to the level of the ductus seminalis inception; the ductus bursae runs from here to the corpus bursae. The transition from ductus to corpus bursae is here taken as indicated by the cessation of folding and / or lightening of Chlorazol Black stain.
Larvae. In larval descriptions adapted from Hudson (1928), only coloration is given; Hudson’s references to ‘bristles’ (i.e., setae) and ‘warts’ (i.e., pinacula) are generally omitted, since they are not detailed enough to provide species-level characters. The chaetotaxy and arrangement of plates and pinacula are covered in the genus description, and are not known to vary substantially between species.
A standardised list of characters has been described for all species. Additional characters of interest, unique to a particular species or species-pair, are occasionally included (e.g., lobes at the base of the uncus in I. rigescens); such characters are placed in parentheses. Ranges of wingspan and forewing length given for each species represent the extremes for the material examined.
Repository of specimens and label data
The following acronyms are used for collections where specimens are held:
AMNZ: Auckland Museum, Auckland, New Zealand
BLNZ: Brian Lyford private collection, Queenstown, New Zealand
BMNH: British Museum (Natural History), London, England
CMNZ: Canterbury Museum, Christchurch, New Zealand
LUNZ: Entomology Research Museum, Lincoln University, New Zealand
MONZ: Museum of New Zealand, Wellington, New Zealand
NHNZ: Neville Hudson private collection, Auckland, New Zealand
NZAC: New Zealand Arthropod Collection, Landcare Research, Auckland, New Zealand
OMNZ: Otago Museum, Dunedin, New Zealand
Data for primary types are quoted exactly, from the top label down, the data on separate labels being segregated by slashes [/]. Paratype label data are given as far as possible in standard format. The following abbreviations are used for names of frequently mentioned collectors: AP, Alfred Philpott; BHP, Brian H. Patrick; GWG, George W. Gibbs; GH, Grace Hall; GVH, George V. Hudson; HP, Hamish Patrick; JSD, John S. Dugdale; KJF, Kenneth J. Fox; RJBH, Robert J. B. Hoare. Where ‘HP’ appears twice on the data of a single specimen, the second ‘HP’ is Holly Patrick.
Two-letter codes for collecting localities within New Zealand follow Crosby et al. (1998).
Primary type specimens have been examined for all available names, except adapertella Walker, 1864 and amorbas Meyrick, 1910, for which the holotypes are apparently lost. Unless a genitalia slide number is quoted in the type label data below, the primary type has not been dissected for genitalia examination. In all cases where genitalia have not been examined, the identity of the type specimen is deemed to be unambiguous based on external characters and/or locality. For all species, males and females from a selection of localities throughout the distributional range have been dissected to establish variation and species boundaries.
Species concept and order
The species concept adopted here is a morphological one, i.e., I have treated as separate species only those entities showing constant and easily definable morphological differences, with particular weight being given to genitalic characters (cf., Scoble et al. 1995; Hoare 2005). Morphological separation is taken to be indicative of reproductive isolation, as per the Biological Species Concept.
The order of species groups has been determined on the following basis. The first 5 species groups are those considered most likely to prove monophyletic, and these are arranged roughly in order of increasing morphological complexity and/or specialisation, keeping related groups (e.g., the mira- and apodoxa-groups) close together. The oleariae-group is anomalous, and apparently without close relatives, so is placed last in this series. The remaining 2 groups contain the less easily placed taxa and are the most tentative; the groups are placed in alphabetical order of the species after which they are named. Within their species groups, species that are believed to be closely related are grouped together; otherwise alphabetical order is followed. Whilst the order adopted here is admittedly based on subjective criteria, and must be subject to revision following phylogenetic studies, it should maximise ease of identification by placing related and similar species close together in the figures and text, and was therefore considered preferable to a purely alphabetical arrangement.
Scientific names of plants follow the New Zealand Plants (2004) website.