The following is a general instruction for identifying Phasmatodea, not only for breeders but also for people wanting to identify preserved phasmids in their cabinets. An increasing number of new stocks of so far unidentified species is introduced to Europe currently, but often it takes a long time to make a confirmed identification. So, let’s find out why.
1. Difficulties of identification
Undoubtedly, the Phasmatodea are an order in which the identification exclusively upon examination and comparison of morphological features of the insects can be problematic. The order is still poorly studied if compared to e.g. Coleoptera or Lepidoptera, and frequently numerous new species, genera or even higher ordinate taxa like tribes and subfamilies are discovered on modern expeditions and prospections of certain habitats. Currently, some 2600 valid species are known, numerous of which are still of a rather uncertain or provisional systematic position within the classification. The main difficulties in identifying Phasmatodea can be summarized as follows:
1. Inadequate descriptions. The first Phasmid species were described by Carl von LINNÉ in 1758. Many of the species descriptions published up to the 20th century are very brief and nowadays are useless for identifying species. During the 19th century it was usual to characterize a species by only a single sentence, or a couple of insufiiciently characterizing features. Unfortunately, this problem is also the case with the perhaps most famous publication of the 20th century, the monography “Die Insektenfamilie der Phasmiden” by BRUNNER v. WATTENWYL & REDTENBACHER (1906-1908).
2. Sexual dimorphism. Phasmids often exhibit a remarkable sexual dimorphism with females looking very different than the corresponding males. There are quite a few cases in which a the opposite sexes of one species were described not only as two distinct species, but even in two different genera!
3. Intraspecific variation. Numerous species (subfamily Lonchodinae in particular) exhibit extreme intraspecific variability concerning to certain morphological features of the female insects such as the colouration, size, sculpturing of the body surface, spination, shape of the lobes on the legs or head armature. In same cases the variation can be so extreme and individual that hardly two identical specimens are found even amongst a series of several dozends of specimens.
4. Unique specimens / nymphs. Many species were inadequately described from a single male or female only, and in some cases the concerned specimen (holotype) is either not traced or known to have been destroyed. Other species were described from nymphs only, which may look very different from the adults, and hence make an identification of adult insects impossible.
5. Use of phylogenetically irrelevant criterions. The Phasmatodea are real masters of camouflage. Hence they often exhibit a wide range of conspicuous morphological “features”, which at first glance pretend to be useful for the distinction of species, genera or higher ordinate taxa. However, many of these “features” are merely adaptions to the natural environment in which a certain species lives. Features that underlie less evolutionary pressure and are constant within taxa are e.g. the genitalia or eggs. Often it deserves captive breeding and quite some expierience with certain subgroups to decide on the phylogenetic relevance of a feature. Unfortunately, several of the phylogenetically relevant criterions were completely left out of account by authors in the 18th and 19th century.
6. KIRBY´s „A synonymic catalogue of Orthoptera“ of 1904. BRUNNER v. WATTENWYL & REDTENBACHER (1906-1908) list valid species in their monography which were treated as synonyms by KIRBY (1904) and type-species designated for numerous genera by KIRBY were left out of account, which has led to much confusion still not solved completely. Since the monograph excludes any reference to KIRBY’s catalogue there seems to have been no liaison between these well-known scientists.
2. Where to start? Important Publications & Monographs
As the Phasmatodea are still poorly studied you will need access to a good selection of primary literature. Copies or PDF-files of original publications can obtained from public libraries or via libraries in the internet. Two historical and fairly essential publications are:
WESTWOOD, J. O. (1859): Catalogue of Orthopterous insects in the collection of the British Museum. Part 1, Phasmidae. British Museum, London, 196 pp., 40 plates.
BRUNNER v. WATTENWYL, C. & REDTENBACHER, J. (1906-1908): Die Insektenfamilie der Phasmiden, Teil 1-3. Verlag Wilhelm Engelmann, Leipzig, 589 S., 27 Tafeln. [Authorship: Part 1 (1906) & 3 (1908): REDTENBACHER; Part 2 (1907): C. BRUNNER v. WATTENWYL]
Both works contain a reasonable number of very accurate black and white plates, which either show the complete insects or details of the genitalia or head. The latter includes an illustration of at least one species in almost all genera known at that time.
3. Geographical regions & local faunas
If you are examining Phasmatodea from specific countries or island, it is advisable to obtain primary or secondary literature that deals with the concerned faunas. Whenever you work with historic publications you must take into account that often the recorded localities are based on specimens collected in the late 18th or early 19th century and that the increasing destruction of natural habitats during the past 100 years may have changed the original habitats fundamentally!
The majority of publications since the early 20th century deal with certain faunas. The Phasmatodea of some countries are rather well studied but future collections from remote areas may still produces undescribed species. There are essential more or less complete publications available for the following regions, countries or islands:
BROCK, P.D. & HASENPUSCH, J. (2007): Studies on the Australian stick insects (Phasmida), including a checklist of species and bibliography. Zootaxa, 1570: 3-84.
BROCK, P.D. & HASENPUSCH, J. (2009): The Complete Field Guide to Stick and Leaf Insects of Australia. CSIRO Publishing, Australia. 204 pp.
BRAGG, P. E. (2001): Phasmids of Borneo. Natural History Publications (Borneo), Kota Kinabalu, 772 pp.
CHEN, S. C. & HE, Y. H. (2007): Phasmatodea of China. China Forestry Publishing House. 476 pp, 12 plates.
HENNEMANN, F. H., CONLE, O. V. & ZHANG, W. W. (2008): Catalogue of the Stick and Leaf-insects (Phasmatodea) of China, with a faunistic analysis, review of recent ecological and biological studies and bibliography (Insecta: Orthoptera: Phasmatodea). Zootaxa, 1735: 3-77.
LELONG, P., LANGLOIS, F., RASTEL, D. & DOREL, E. (2003): Phasmatodea of Dominica. ASPER Publishing, Ste Foy D' Aigrefueille, Frankreich. 103 pp. + appendix.
CHOPARD, L. (1912): Contribution a la faune des Orthoptères de la Guyane Française. Annales de la Société entomologique de France, 80: 315-349.
LANGLOIS, F. & LELONG, P. (1998): Phasmatodea de Guadeloupe. ASPER Publishing, Ste Foy D' Aigrefueille, Frankreich. 88 pp. + appendix.
BROCK, P.D. & SHLAGMAN, A. (1994): The stick-insects (Phasmatodea) of Israel, including the Description of a new species. Israel Journal of Entomology, 28: 101-117.
JAPAN & TAIWAN
OKADA, M. (1999): Nanafushí-No-Subete (All About Stick-Insects). Tonbo-Shuppan Publishing, Osaka. 56 pp. [In Japanese]
SHIRAKI, T. (1935): Orthoptera of the Japanese Empire (Part IV) Phasmidae. Memoires of the Faculty of Science and Agriculture, Taihokalmp. University, Formosa, 14(3): 23-88, plates 4-10.
LANGLOIS, F., LELONG, P., RASTEL, D., POLIDORI, E. & DOREL, E. (2000): Phasmatodea de Martinque. ASPER Publishing, Ste Foy D' Aigrefueille, Frankreich. 74 pp. + appendix.
KEVAN, D. K., McE. & VICKERY, V.R. (1997): An annotated provisional list of Non-altatorial Orthopteroid Insects of Micronesia, compiled mainly from literature. Micronesica, 30(2): 269-353.
GÜNTHER, K. (1929): Die Phasmoiden der Deutschen Kaiserin Augusta-Fluss-Expedition 1912/13. Ein Beitrag zur Kenntnis der Phasmoidenfauna Neuguineas. Mitteilungen aus dem Zoologischen Museum, Berlin, 17: 753-835.
HERWAARDEN, H. van (1998): A guide to the genera of stick- and leaf-Insects (Insecta: Phasmida) of New Guinea and the surrounding islands. Science in New Guinea, 24(2): 55-114.
NEW CALEDONIA & LOYALTY-ISLANDS
CARL, J. (1915): Phasmiden von Neu-Caledonien und den Loyalty-Inseln. In: Sarasin, F. & Roux, J. [Eds.]: Forschungen in Neu-Caledonia. Zoologie, (2)2(9): 173-194.
SALMON, J. T. (1991): The stick insects of New Zealand. Reed Books, New Zealand. 124 pp.
JEWELL, T. & BROCK, P.D. (2003): A review of the New Zealand stick-insects: new genera and synonymy, keys, and a catalogue. Journal of Orthoptera Research, 11(2): 189-197.
LANGLOIS, F., LELONG, P. & DOREL, E. (2006): Phasmatodea of Saint Lucia. ASPER Publishing, Ste Foy D' Aigrefueille, France. 68 pp. + appendix.
HENNEMANN, F. H. (2002): Notes on the Phasmatodea of Sri Lanka. Mitteilungen der Münchner Entomologischen Gesellschaft, 92: 37-78.
HENNEMANN, F. H. (1998): Ein Beitrag zur Kenntnis der Phasmidenfauna von Sulawesi. Mit einem Katalog der bisher bekanntgewordenen Arten. Mitteilungen aus dem Museum für Naturkunde, Berlin, Zoologische Reihe, 74(1): 95-128.
WEST MALAYSIA & SINGAPORE
BROCK, P.D. (1999): Stick and Leaf Insects of Peninsular Malaysia and Singapore. Malaysian Nature Society, Kuala Lumpur. 223 pp.
SEOW-CHOEN, F. (2000): An Illustrated Guide to the Stick and Leaf Insects of Peninsular Malaysia and Singapore. Natural History Publications (Borneo), Kota Kinabalu. 173 pp.
4. Search for literature after 1930
Ulf CARLBERG has published a bibliographical list, his „Bibliography of Phasmida“, which is splitted into seven papers (1983, 1985, 1986, 1987a & b, 1988, 1994). These provide complete references of almost all publications dealing with Phasmatodea and useful species indexes for the periods 1930-39; 1940-49; 1950-59; 1960-69; 1970-79; 1980-84 and 1985-89. They are quite helpful for researching species.
CARLBERG, U. (1983): Bibliography of Phasmida (Insecta) I: 1970-79. Spixiana, 6(1): 27-43.
CARLBERG, U. (1985): Bibliography of Phasmida (Insecta) II: 1960-69. Beiträge zur Entomologie, Berlin, 35(1): 3-12.
CARLBERG, U. (1986): Bibliography of Phasmida (Insecta) III: 1950-59. Beiträge zur Entomologie, Berlin, 36(2): 255-260.
CARLBERG, U. (1987a): Bibliography of Phasmida (Insecta) IV: 1980-84. Beiträge zur Entomologie, Berlin, 37(1): 197-202.
CARLBERG, U. (1987b): Bibliography of Phasmida (Insecta) VI: 1980-84. Spixiana, 10(2): 147-156.
CARLBERG, U. (1988): Bibliography of Phasmida (Insecta) V: 1930-39. Beiträge zur Entomologie, Berlin, 38(1): 277-287.
CARLBERG, U. (1994a): Bibliography of Phasmida (Insecta) VII: 1985-1989. Spixiana, 17(2): 179-191.
CARLBERG, U. (1994b): Bibliography of Phasmida (Insecta) VIII: Supplement I. 1930-1984. Beiträge zur Entomologie, Berlin, 44(1): 243-250.
When you have the necessary primary literature you should first examine the plates in WESTWOOD (1859) and BRUNNER v. WATTENWYL & REDTENBACHER (1906-1908) to find a similar insect to the one you are seeking to identify. Apart from a similar general habitus and suitable distribution, pay particular attention to the wing shape and size (if winged), length relations of body segments, length of the antennae and legs in relation to the body, and body or leg structures such as spines, teeth, tubercles or lobes, and shape of the genitalia of course. In some winged groups even the arrangement of the veins can be of importance for the distinction of higher ordinate taxa.
With luck you may find exactly the species or a very similar species to the one you are searching for, in which case you should look up the description in order to check the localities, measurements, colouration and other features that cannot be seen in the illustration. These are in English (WESTWOOD) or Latin with German comments (BRUNNER v. WATTENWYL & REDTENBACHER). The latter work furthermore provides identification keys to all genera and all species in each genus, which are mostly fairly simple to translate and easy to work with. If no matching species was found it is advisable to examine further literature that either deals with closely related taxa or species from the concerned country or island.
Finally, for going sure you should compare your insects with the original type-specimen(s) which are mostly housed in museum collections throughout the world. If there is no possibility for you to visit the museum which houses thespecific type-specimen you need to see, the corresponding curator may help out with photos or comparison of your specimen.
There are sometimes several nearly identical or very similar species in a genus. In such cases try to establish the distinctive features mentioned in the literature and use a microscope or magnifying glass for carefully checking these structures (e.g. shape and size of cerci, granules on the thorax).
6. Phasmida Species File
The Phasmida Species File (author: Paul D. BROCK) is a taxonomic database of the world’s Phasmatodea, which includes basic data from OTTE & BROCK’s 2005 “Catalog of the Stick and Leaf Insects of the World” as well as thousands of photos of type-specimens, numerous literature refernces and is continuously updated. As a second step this collossal online database is certainly the best modern tool for identifying Phasmatodea and the definitive source of information about phasmid names.
OTTE, D. & BROCK, P. (2005): Phasmida Species File. Catalog of the Stick and Leaf Insects of the World. 2nd Edition. The Insect Diversity Association at the Academy of Natural Sciences, Philadelphia. 414 S.