Pison, Jurine, 1808

Pulawski, Wojciech J., 2018, A Revision of the Wasp Genus Pison Jurine, 1808 of Australia and New Zealand, New Guinea, and the Pacific Islands (Hymenoptera: Crabronidae), Proceedings of the California Academy of Sciences 65, pp. 1-584 : 8-9

PISON OF AUSTRALIA AND NEW ZEALAND

The fauna of the Australian Pison is extraordinarily rich, far exceeding the numbers of its congeners in the other Zoogeographic Regions. Taking into account the new synonymies and the four species recently transferred to Aulacophilinus , 45 species are currently known from the continent. In this paper, I recognize 163 species, 117 of which are new. In comparison, 44 species occur in the Neotropical Region according to the recent revision by Menke (1988), with one species added by Antropov (1996), 21 occur in Sub-Saharan Africa excluding Madagascar (Leclercq, 1965), 12 in China (T. Li and Q. Li, 2011), and 10 in the Philippines (Tsuneki, 1983a).

Beyond the 163 species that I now recognize from Australia, there remain an indefinite number of forms that are difficult to characterize. Most of these are all black and small to medium size, and lack conspicuous distinctive features. These forms are represented by only one or a few specimens each in the material studied, making it difficult to determine whether they are new species, or variants or geographic races of recognized species, or opposite sexes of species known from one sex only. Certainly, the number of the Australian Pison will significantly increase when these forms are clarified.

Clearly, the current study cannot be regarded as a definitive or final revision of the Australian Pison . I like to think, nevertheless, that it is a significant step forward in our knowledge of this wasp genus

TAXONOMIC HISTORY OF AUSTRALIAN PISON . – Shuckard (1828), the first author who dealt with the Australian Pison , described P. rufipes , P. spinolae , and P. westwoodi . He was followed by Le Guillou (1841) who described P. peletieri , and by F. Smith who described four species in 1856 and eleven in 1869. Kohl (1884), Turner (1908, 1915), and Rohwer (1915) added one, fourteen and one, and two species, respectively, and Turner (1916) described an additional eleven. Evans (1981) with three species, and Menke (2015) with one species, are the latest additions. Fifteen of these names are now junior synonyms. The caliginosum species group of Pison , revised by Naumann (1990), is now regarded as belonging to Aulacophilinus (Menke, 2016; Pulawski, 2017).

In 1915, Turner published a key to the four known Tasmanian species; in the key he incorrectly attributed to P. westwoodii the second recurrent vein joining the second submarginal cell. In the following year, he (Turner, 1916) published the first and so far the only key to all Australian species. He took into consideration the 50 species known by then, and he was able to study firsthand the species described by F. Smith. The key, however, contained less than a third of the species now known to occur in Australia. It also contained three grave errors: P. peletieri , P. vestitum , and Turner’s own P. scabrum were assigned to wrong key sections. Because of his limited material, Turner was not able to appreciate the amount of individual variation and treated as valid the following six species that actually are junior synonyms: P. aureosericeum , P. exornatum , P. fraterculus , P. fuscipenne , P. pulchrinum , and P. scabrum . He did not see the type of P. peletieri Le Guillou, 1841 and did not recognize that this is the valid name for P. ruficorne F. Smith, 1856 . Also, he did not notice a number of important characters, even those that can be observed with a simple hand lens (e.g., the presence of erect setae on tergum I).

Generally, very little progress in the taxonomy of the Australian Pison has been achieved in the last 100 years. An important exception was the discovery, by Evans (1981), of the species nesting in the soil and the correlation with the presence of the psammophores.

Prior to this study, our knowledge of the Australian species was quite insufficient for two main reasons: (1) a good number of excellent recognition characters had never been used for species characterizations, and (2) more than a hundred species were waiting to be discovered.

SUBDIVISIONS OF AUSTRALIAN / NEW ZEALAND PISON . – Menke (1988) divided the South American Pison into 12 species groups (two of which, the convexifrons group and the pilosum group, are now placed in Entomopison ). I was unable, however, to produce a similar group recognition for the Australian species, mainly because of the absence of clear-cut divisions between species, as well as their great number and diversity. The following examples illustrate the difficulties that I have encountered:

(1) The subgenus Pisonoides was proposed for the species with only two submarginal cells, but the number of cells is variable in some species. For example, a male of Pison marginatum from Sunny Corner area, New South Wales (CAS) and a female of Pison westwoodii from Mount Lewis near Mossman, Queensland (CAS), have two submarginal cells in the left wing and three in the right wing. Furthermore, most specimens of P. laeve have three submarginal cells, but one male examined has only two. Similarly, most New Zealand specimens of P. spinolae have three submarginal cells, but many have only two (Harris, 1994). Clearly, the boundary between species with three submarginal cells and those with two is fluid.

(2) The subgenus Pisonitus was described to include the species in which the second recurrent vein is received near the middle of the second submarginal cell (rather than being interstitial with the second intersubmarginal vein or nearly so). The second recurrent vein, however, is received near two thirds of the length in P. peletieri from Papua New Guinea, and near two thirds to three quarters of the length in P. leptogaster , P. orbitale , and some P. nigricans . Therefore, these two separate types cannot be maintained.

(3) Based on its distinctly setose eyes, Pison trichops should be treated as a member of the agile species group of Menke. A closer analysis suggests, however, that the setose eyes may be an independent acquisition (see that species for details). P. deplanatum , in which the eyes are setose only above the eye emargination, seems to be halfway between the agile species group and the other Pison .

(4) The difference between those Australian Pison in which tergum I has erect setae and those in which the setae of tergum I are appressed seems well defined at first glance, but in fact the erect setae vary greatly among species in length and the area they cover. Also, in most P. vestitum the setae are erect on tergum I, but appressed in some specimens. Here again, the group difference is collapsing.

(5) Perhaps the most conspicuous are the species in which the females have a genal psammophore (used to carry the sand away during nest excavation). There is, however, significant variation among these species: most have also a well-defined forefemoral psammophore, but some lack it ( P. argentifrons , P. auriventre , P. stenometopon ). Pison minutum , however, is intermediate: its psammophore is unusually short (only 0.5-0.6 × midocellar diameter), present on the forefemur, but absent on the gena in some specimens.