Pelodiaetus sulcatipennis Jeannel

Sokolov, Igor M., 2019, A review of the genus Pelodiaetus Jeannel (Coleoptera, Carabidae, Anillini) of New Zealand, with re-description of the genus, description of a new species, and notes on the evolutionary history, ZooKeys 879, pp. 33-56 : 44-48

Pelodiaetus sulcatipennis Jeannel

Pelodiaetus sulcatipennis Jeannel, 1937: 277 (original description); Jeannel 1963 (figures, key, distribution); Moore 1980 (key, distribution).

Pelodiaetus lewisi Jeannel, 1937: 277 (original description), syn. nov.; Jeannel 1963 (key, distribution); Moore 1980 (key, distribution).

Investigated material.

Stewart Island: Ulva Island Nov-Dec 2003 /coastal forest litter (5 specimens).

Southland: Tussock Creek Forest Hill Res 1 Sep 07 / Washed soil sample. Wet Podocarp/broadleaf forest (4 specimens); New Zealand SL Forest Hill Res nr Edendale 1 Sep 07 / Washed soil sample. Kahikitea forest (3 specimens); New Zealand SL Alton Burn Tuatapere SR 16 Nov 08 / Washed soil sample, totara/beech forest / NZMS 260 D45: 992419 38m (4 specimens); New Zealand SL Tuatapere Domain Tuatapere SR 16 Nov 08 / Washed soil sample, beech forest / NZMS 260 D45: 993403 30m (1 specimen); New Zealand SL Tuatapere Scenic Reserve at Tuatapere Domain, 30m J.Nunn 16 Nov 08 / Molecular voucher # 104 Sokolov I.M 2009 (1 specimen); New Zealand SL Tuatapere Scenic Reserve at Tuatapere Domain, 30m J.Nunn 16 Nov 08 / Molecular voucher # 107 Sokolov I.M 2009 (1 specimen); New Zealand SL Bog Burn Taringatura Forest 2 Jan 09 / Washed soil sample, beech forest / NZMS 260 E45: 397596 250m (1 specimen); New Zealand SL Dunsdale Stream, Hokonui Hills, 110m, washed soil sample J.Nunn 26 April 08 / Molecular voucher # 100 Sokolov I.M 2009 (1 specimen); New Zealand MC Pudding Hill Reserve Mt. Hutt 700m J.Nunn 25 Oct 08 / Molecular voucher # 105 Sokolov I.M 2009 (1 specimen); SL Chloris Pass, Catlins 17 Jun 06 (7 specimens); Rakahouka 2 Sep 07 /Neaopanax forest (2 specimens).

Dunedin: Woodside Glen, Outram 18 Nov 06 (3 specimens); Sutton, Salt Lake 21 Jun 09 / tussock and improved pasture (2 specimens); Picnic Gulley, Taieri Mouth 18 May 06 / under stone after rain (29 specimens); New Zealand DN Start of Government Tck Waipori Valley / Washed soil sample 17 Dec 06 (1 specimen).

Central Otago: Logan Burn 900m 13 Dec 1982 / ex. Oreobolus pectinatus (3 specimens); Cromwell, Kawarau Gorge, Roaring Meg 500m 12 Mar 1959 (2 specimens); Garden V., Raggedy Range 10 Sept 68 / Raoulia (1 specimen); Alexandra Hills, the Knobbies 10 Sept 68 / Raoulia (1 specimen).

South Canterbury: Guns Bush Waimate 23 Dec 06 / Washed soil sample, broadleaf forest (1 female).

Discussion.

As mentioned above, the genus Pelodiaetus was established by Jeannel (1937) for two species: P. sulcatipennis and P. lewisi . Both species were collected together in Dunedin, Otago, by G Lewis, and, according to Jeannel (1937, 1963), they can be distinguished from each other by the shape of the pronotum and elytra. In their descriptions, Jeannel did not provide comparison of the genitalia of the two species, and obviously did not make the necessary measurements for comparison of above-mentioned body parts. He simply restricted description to two couplets of a key with very general diagnoses: a more transverse and rounded pronotum with shorter and more convex elytra for P. sulcatipennis , and a correspondingly less transverse and rounded pronotum, and narrower and more elongated elytra, for P. lewisi . This short and very general comparison, together with the same type locality, made the validity of two forms questionable. Later, Moore (1980), reviewing the New Zealand Anillini , paid attention to the presence of intermediates in the body shape between the two species and stated that both names may belong to extremes of the same species, but did not formally synonymize these taxa because of the scarcity of the available material.

Preparing this taxonomic review, I had an opportunity to investigate many more representatives of the genus. For analysis of the variation in body part proportions, measurements of 57 members of the genus were completed, including seven specimens of P. nunni and 50 specimens of P. sulcatipennis . Because of the wide range of P. sulcatipennis , the aim of this investigation was to compare main body ratios between the northeastern and southwestern parts of its range. All investigated ratios showed no difference between the two populations of P. sulcatipennis , as well as between the latter’s populations and the representatives of P. nunni. At the same time, many ratios showed rather high interspecies variability; this was especially true for W/L - ratio of maximal width to length along the midline of the pronotum, one of the characters used by Jeannel for distinguishing his species. According to the obtained data, the variation in the proportions of the pronotum ( Fig. 9 ) is similar across different species of Pelodiaetus (T-test for independent groups, p = 0.693, n = 7 for P. nunni , and n = 50 for P. sulcatipennis ) and between different populations of P. sulcatipennis (T-test for independent groups, p = 0.095, n = 23 for mid-eastern, and n = 27 for south-western populations). The only difference between populations of P. sulcatipennis can be seen in the light shift towards the prevalence of specimens with a slightly more transverse pronotum in the southwestern part of range. However, this deviation lies within the error range and is not statistically significant (see above). The type locality of P. sulcatipennis and P. lewisi (Dunedin, Otago) is located exactly within the range of the mid-eastern population, thus supporting the point of view of Moore that both Jeannel’s species may belong to extremes of a single species. In addition, in investigating male genitalia, I was unable to find any constant difference in the shape of the median lobe and in the armature of the internal sac. On the basis of this evidence, P. sulcatipennis and P. lewisi should be considered as variations of the same species and be synonymized under the name of Pelodiaetus sulcatipennis Jeannel.

Figures

Figure 8. Map of southern half of South Island, New Zealand, showing positions of locality records for the species of Pelodiaetus: P. nunni, white circles; P. sulcatipennis, yellow circles. Elevation scale bars are given in meters.

Figure 9. Variation in proportions of pronotum among different taxa and populations of Pelodiaetus. A - P. nunni; B - P. sulcatipennis, mid-eastern populations; C - P. sulcatipennis, south-western populations. Map of southern half of South Island, New Zealand, shows localities from where specimens were measured. Each species location dot (yellow or white) is identical to Fig. 8 but they are additionally marked with the appropriate bar graph color: pink, orange, and blue. X-axis values represent W / L - ratio of maximal width to length along the midline of pronotum. Red curve - expected normal distribution with sample mean and standard deviation. Elevation scale bars are given in meters.