Volume 24: 7–11 METAMORPHOSIS ISSN 1018–6490 (PRINT) LEPIDOPTERISTS’ SOCIETY OF AFRICA ISSN 2307–5031 (ONLINE) A study of the genitalia of Precis actia (Distant), 1880 and Precis pelarga (Fabricius), 1775 (Lepidoptera: Nymphalidae) Published online: 14 June 2013 Ian D. Richardson Gibertou, 82390 Durfort Lacapelette, France. E-mail : [email protected] Copyright © Lepidopterists’ Society of Africa Abstract: The diagnostic character based on the position of a dot in a light coloured patch on the forewing is quantified for each male specimen in short series of Precis actia and Precis pelarga from Zambia. A study of the male genitalia reveals an additional diagnostic character, which correlates well with the quantified dot-position character. This additional character is proposed as a more definitive means of separating the two very similar species. Key words: Afrotropical Lepidoptera, Nymphalidae, Nymphalinae, Precis, actia, pelarga, male genitalia Citation: Richardson, I.D. (2013). A study of the genitalia of Precis actia (Distant), 1880 and Precis pelarga (Fabricius), 1775 (Lepidoptera: Nymphalidae). Metamorphosis 24: 7–11. INTRODUCTION published work on the genitalia of these two species. The distinction between Precis actia (Distant), This prompted a study of the genitalia of the nine 1880 and Precis pelarga (Fabricius), 1775 is male specimens, covering both species, in the given by Kielland (1990) as follows: “[P. actia] author’s collection. differs from P. pelarga in the squarish post-discal patch in space 3 with the black dot placed in the MATERIAL AND METHODS centre of it (in pelarga the black dot is placed closer to the distal border)”. Dot Position This key to identifying the two species is Fig. 1 shows a male Precis that would most likely adequate in some cases where the dot is on the be identified as P. pelarga on account of the dot proximal side of the centre, P. actia, or is well to in the ringed orange patch being closer to the the distal side of the centre, P. pelarga. However, distal edge. Arriving at this decision involves the key can be difficult to apply, for example: making a judgement about where the proximal 1. The edges of the patch are curved and so and distal edges of the patch lie. To quantify the the definition of centre is ambiguous. position of the dot, a process is defined for 2. The dot appears slightly on the distal making this judgement. side of centre, but is it far enough from centre to qualify as P. pelarga? A simple method has been devised to quantify the position of the dot within the patch, thereby reducing the subjective element of the dot- position character. The problem still remains, though, of defining the transition point between P. actia and P. pelarga. Heath et al. (2002) state that there are differences in the genitalia between the two species, but it has not been possible to track down published documentation. Dr Torben Larsen and Professor Mark Williams are also not aware of any Figure 1 – Male P. pelarga with the squarish patch in space 3 Received: 26 March 2013 of the left forewing ringed in yellow Accepted: 14 June 2013 Fig. 2 shows the ringed patch of the same Copyright: This work is licensed under the Creative specimen enlarged and rotated so that veins 3 and Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, send a 4 are horizontal. In fact, both veins are slightly letter to Creative Commons, Second Street, Suite 300, curved and may in some cases diverge, so the San Francisco, California, 94105, USA, or visit: patch is orientated to obtain both veins as near as http://creative commons.org/licenses/by-nc-nd/3.0/ possible horizontal. Richardson/ Metamorphosis 24: 7–11 8 D = dprox / (dprox + ddist) The final value for D is the mean of the values determined for the left and right wings. In this case, D evaluates to 0.6 confirming the initial impression that this is likely to be P. pelarga. It is evident that D is 0.0 when the dot is on the proximal edge, 0.5 when it is in the centre of the patch and 1.0 when it is on the distal edge. Male Genitalia Figure 2 – The squarish post-discal patch with the black dot The genitalia were extracted and prepared for all placed near its centre nine specimens by the following procedure: 1. The abdomen was detached from the The close-up of the patch is cut from the image of thorax and wetted in 95% ethyl alcohol the whole specimen using Microsoft Office solution for 10 minutes. Picture Manager. The image of the patch is 2. The abdomen was removed from the rotated using Microsoft PowerPoint and alcohol and placed in 10% potassium enlarged so that the width of the patch is hydroxide solution at room temperature. approximately 5 cm on the PowerPoint slide. 3. After approximately 10 hours the Two straight, yellow lines are drawn, one along abdomen was removed from the vein 3 and one along vein 4, as shown in Fig. 3. potassium hydroxide solution and immersed in 20% ethyl alcohol solution for 10 minutes. 4. The abdomen was transferred to a Syracuse watch glass containing clean 20% ethyl alcohol solution and the genitalia were extracted under a low power microscope using forceps and a probe. 5. The genitalia were cleaned to remove scales and any attached soft material. To complete the cleaning, the genitalia were transferred to a clean watch glass and 20% alcohol solution. Figure 3 – Quantification of the position of the black dot in 6. The aedeagus was removed from the the square patch genitalia. 7. Genitalia were examined and These lines are parallel and define the top and photographed under glycerine in a small bottom edges of the patch. The sides of the patch, plastic well. labelled proximal and distal edges, are then drawn 8. The photographs of the genitalia were at right angles to the top and bottom edges. taken through one eyepiece of the The proximal and distal edges are adjusted left microscope with a Canon EOS 400D and right until they are judged to be a best fit to camera. the edge of the light patch on the wing. In the 9. The genitalia including aedeagus were example illustrated, the position of the distal edge transferred to a vial containing glycerine of the patch is easily enough defined. However, for storage and the vial was labelled with the proximal edge is distorted by a lobe projecting the specimen ID and the dissection ID. in from the black discal area of the wing. The position of the proximal edge line is adjusted in Gazetteer this case until there is judged to be as much dark The co-ordinates of the capture localities for the area within the patch as there is light (orange) nine specimens examined in this study are listed area outside. in Table 1. The position of the centre of the dot in the patch is marked by a yellow dot. Locality Latitude Longitude Altitude The PowerPoint function “snap to grid” is used (dd:mm:ss) (dd:mm:ss) (m) with the grid spacing set to 0.2 cm. Consequently Lumangwe 09:32:34 S 29:23:17 E 1172 the positions of the distal edge, proximal edge and Falls dot centre are all defined to the nearest 0.2 cm on Kundabwika 09:13:03 S 29:18:15 E 1023 Falls the PowerPoint slide. Mutinondo The distance from the dot centre to the proximal 12:26:50 S 31:17:15 E 1458 and distal edges is indicated in Fig. 3 by the red Nkamba Bay 08:36:15 S 30:31:56 E 789 lines annotated dprox and ddist. Then a parameter D quantifying the position of the dot within the Table 1: The capture localities in Northern Zambia. patch is given by: Richardson/ Metamorphosis 24: 7–11 9 Figure 4 – Thumbnails of the nine male specimens studied with capture date, locality and dot position D RESULTS that the number of spines increased with decreasing dot position, D, this feature Dot Position was very variable and assessed as Thumbnail images of the nine males are shown in unhelpful for separating the two species. Fig. 4, where they are arranged in order of The aedeagus of specimen no. 2 is increasing value of D. Although this is a small shown in Fig. 5. sample, the specimens cover dry season and wet 2. The valves terminate at the posterior end season forms as well as four localities distributed in a short stem with claw-like spikes that around Northern Zambia. curve inwards towards the aedeagus. The confidence in the estimates of D is determined from the uncertainty in the position of the dot centre, the distal edge and the proximal edge of the patch. Typically these uncertainties were approximately one PowerPoint grid spacing, i.e. ± 0.2 cm, which evaluate to a 2 σ error on D of approximately ± 0.05. Male Genitalia Three candidate features were noted: 1. The number of spines on the two sides of the aedeagus near the tip varied considerably over the nine specimens. Although there appeared to be a trend Figure 5 – Aedeagus, dorsal & lateral views (specimen no. 2) Richardson/ Metamorphosis 24: 7–11 10 For specimens with the dot closer to the proximal edge the valve has a three or four claw termination (see Figs 6 and 7). For specimens with the dot closer to the distal edge of the square patch the valve has a two claw termination (see Fig.