Identification of Maoricicada species
Genus Maoricicada Dugdale, 1972
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Type species: Maoricicada campbelli Myers, 1923 |
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Introduction. This genus Maoricicada was reviewed taxonomically by Dugdale & Fleming (1978) and in an earlier paper dealing with lowland species by Fleming (1971), bringing the known fauna to 14 species. Buckley et al. (2002) established the monophyly of the genus and also suggested, through mitochondrial DNA sequence analysis, that cryptic species may be present in Maoricicada. Arensburger et al. (2004b) estimated a total of 19 species once the genus is fully revised. Buckley & Simon (2007) studied the evolutionary radiation of Maoricicada species in relation to the origin of the New Zealand alpine environment. Members of this genus are sometimes referred to as the mountain black cicadas or simply black cicadas.
The catalogue of New Zealand Auchenorrhyncha published by Larivière, Fletcher and Larochelle (2010: Fauna of New Zealand 63) provides a detailed inventory of the fauna, including nomenclature (valid names, synonyms, combinations, and associated bibliographic information),primary type repositories, and information on geographic distribution (including maps), biology and dispersal. Larivière, Fletcher and Larochelle (2010) also includes the common names of catalogued species: Highe Alpine Cicada (M. alticola), Campbell's Cicada (M. campbelli), Screaming Cicada (M. cassiope), Yodelling Cicada (M. clamitans), Hamilton's Cicada (M. hamiltoni), Iolanthe Cicada (M. iolanthe), Lindsay's Cicada (M. lindsayi), Braying Cicada (M. mangu celer), Dun Mountain Cicada (M. mangu gourlayi), Canterbury Scree Cicada (M. mangu mangu), Northern Scree Cicada (M. mangu multicostata), Myers' Cicada (M. myersi), Eastern Subnival Cicada (M. nigra frigida), Western Subnival Cicada (M. nigra nigra), Greater Alpine Black Cicada (M. oromelaena), Southern Speargrass Cicada (M. otagoensis maceweni), Otago Speargrass Cicada (M. otagoensis otagoensis), Southern Dusky CIcada (M. phaeoptera), Northern Dusky Cicada (M. tenuis).
Problems with species identification. Maoricicada species identification is very difficult. Fleming (1971) and Dugdale & Fleming (1978) made good progress towards a taxonomic revision of this genus using morphological and behavioural (songs) characters, and provided much information on the geographic distribution, ecological preferences, and altitudinal range of included species. Unfortunately, they did not provide fully comparative morphological descriptions that adequately support comparison between species. In addition, available morphological descriptions are often biased towards depicting male characteristics and generally accord too much reliability to overall colouration patterns on head, thorax or abdomen; these vary considerably within species or between sexes, and are of limited use when dealing with dead specimens with fainted colours.
Dugdale & Fleming’s (1978: 301–302) identification key to species should be used with extreme caution, e.g., a number of characters of the external morphology have been found not to be exclusive to taxa being keyed, involve exceptions hence lowering their diagnostic value, are poorly worded for comparison within key couplets, contradict the text of the descriptions, cannot be measured accurately, do not have an opposing character in the opposing couplet lead, or, simply do not work for the taxa involved. The key may perhaps work better in areas where external characters can be taken in combination with characters of the internal genitalia, if the latter are used as the ultimate criteria for identification, but less than half the key couplets include such characters (and not necessarily for both sexes).
In their two papers Fleming & Dugdale did, however, provide for all species excellent dorsal habitus drawings (Fleming, 1971: 446, 450, 453, 455 and Dugdale & Fleming, 1978: 305–311), drawings of ventral colour patterns (although these can vary) (Dugdale & Fleming, 1978: 314–317), outlines of male pygophores (Fleming, 1971: 464 and Dugdale & Fleming, 1978: 320–321), drawings of male aedeagal structures (Fleming, 1971: 464 and Dugdale & Fleming, 1978: 322–323), drawings of internal female genitalia (Fleming, 1971: 466 and Dugdale & Fleming, 1978: 325-–27), and drawings of the left tymbal (male) (Fleming, 1971: 460 and Dugdale & Fleming, 1978: 329). Consequently, it is not impossible for a trained taxonomist to identify live or dead specimens using these drawings, pieces of information from the available descriptions, and relying heavily on male and female internal genitalic structures that require to be dissected in order to be examined. This represents a highly convoluted and time-consuming way to obtain an identification, even for the trained taxonomist.
For the non-specialist, species identification – even by seasoned cicada enthusiasts – involves a large measure of guessing work. Identification success relies heavily on being familiar with the male call (or song) and on collecting and observing in locations already known to harbour particular species. In other words, it can be relatively easy to identify live male individuals from their song (if one is familiar with it) or live females found mating with such males, in locations known from published records to harbour certain species. Most other ways to identify Maoricicada species are tentative and totally dependent on the identifier’s level of expertise in this group. For example, the chances of obtaining a correct identification increase as one becomes more familiar with as many of the following factors as possible: which species occur in a particular area; their song (applies to males only); their external morphology (although highly variable for many species, with available descriptions often superficial or biased towards one sex); and their habitat.
Solutions for species identification. What is urgently needed is a comprehensive revision of the genus Maoricicada, one that would include detailed morphological descriptions that are comparative between species and characters such as the genitalia (both sexes), tymbals, opercula, etc. Such revision would also attempt to correlate information from morphological, ecological, behavioural (including acoustic behaviour), and molecular studies. Only then would it be possible to prepare a reliable identification tool based on morphology and to offer a more holistic understanding of this genus. Unfortunately, study datasets (morphological, molecular or otherwise) are too often developed or used in isolation from each other. So far, too much emphasis may have been put on acoustic behaviour at the expense of thorough morphological investigation, and molecular studies have primarily been correlated to geographic and acoustic data, hardly ever to morphological attributes.
In the meantime, it should be possible to increase access to species-level diagnostic information contained in the literature and in New Zealand insect collections – at least for described species – by bringing this information together on the present website and rendering it more palatable to non-specialists while retaining its usability for trained entomologists and cicada specialists.
Hopefully, the preliminary identification aids (Lucid Phoenix key, image gallery, location guide) presented here will go some way to achieve these goals.