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130 Luperina dumerilii (Dumeril's Rustic)
Rare migrant with <50 British records, Aug-Sep |
131 Luperina testacea (Flounced Rustic)
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132 Luperina nickerlii (Sandhill Rustic)
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Separation of L.testacea and L.nickerlii
These two species are similar and variable. They are similarly sized and have the same flight season.
A. Distribution
L.testacea occurs throughout GB while L.nickerlii occurs very locally at a few coastal sites - so away from these sites it should be L.testacea.
The distribution of L.nickerlii subspecies is as follows:
This page largely concerns the separation of ssp demuthi from L.testacea
These two species are similar and variable. They are similarly sized and have the same flight season.
A. Distribution
L.testacea occurs throughout GB while L.nickerlii occurs very locally at a few coastal sites - so away from these sites it should be L.testacea.
The distribution of L.nickerlii subspecies is as follows:
- demuthi: Thames Estuary, Essex and Suffolk;
- gueneei: Newborough Warren, Anglesey, N.Wales, Cheshire, Lancashire;
- leechi: one sandy shingle beach on the Lizard peninsula in S.Cornwall.
This page largely concerns the separation of ssp demuthi from L.testacea
B. Forewing upperside
Specimens that may be L.nickerlii should show a small round oval and a white-outlined kidney mark. According to MBGBI10 L.testacea is always courser textured, with a warmer ochreous-brown ground colour, a larger oval and the kidney mark is not white-outlined. However, ssp demuthi was not described until 1995 and so was not considered in MBGBI10.
In my experience of ssp. demuthi (which is quite extensive now) the oval mark is smaller than in L.testacea, but not necessarily very much smaller; paler than the surrounding ground colour, usually whitish; and often an elongate oval or tear-drop-shaped. The kidney mark nearly always has a white arc on its distal edge; any white surrounding the remainder of the kidney mark is more variable in extent and usually narrower; and the kidney mark as a whole is usually narrower in the long axis of the forewing than is usually seen in L.testacea. By contrast in L.testacea the oval mark shows less colour contrast and is usually round. And its kidney mark may have a pale surround but this is not usually white and is of even breadth around the whole perimeter of the kidney mark. These distinctions are nearly always reliable enough to identify Luperina specimens in Essex without genital determination. I have no experience of the other races of L.nikerlii and do not know if they can be distinguished on similar features.
Specimens that may be L.nickerlii should show a small round oval and a white-outlined kidney mark. According to MBGBI10 L.testacea is always courser textured, with a warmer ochreous-brown ground colour, a larger oval and the kidney mark is not white-outlined. However, ssp demuthi was not described until 1995 and so was not considered in MBGBI10.
In my experience of ssp. demuthi (which is quite extensive now) the oval mark is smaller than in L.testacea, but not necessarily very much smaller; paler than the surrounding ground colour, usually whitish; and often an elongate oval or tear-drop-shaped. The kidney mark nearly always has a white arc on its distal edge; any white surrounding the remainder of the kidney mark is more variable in extent and usually narrower; and the kidney mark as a whole is usually narrower in the long axis of the forewing than is usually seen in L.testacea. By contrast in L.testacea the oval mark shows less colour contrast and is usually round. And its kidney mark may have a pale surround but this is not usually white and is of even breadth around the whole perimeter of the kidney mark. These distinctions are nearly always reliable enough to identify Luperina specimens in Essex without genital determination. I have no experience of the other races of L.nikerlii and do not know if they can be distinguished on similar features.
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C. Hindwing upperside
In L.testacea the hindwing may be white, brownish-white or occasionally grey; the termen is marked by a fine dark line and the veins are often darkened. In L.nickerlii the hindwing is usually silky white, but in ssp demuthi it may have brownish edges. Ssp demuthi cannot be reliably separated on hindwing markings, but the silkier texture is distinctive if looked for.
In L.testacea the hindwing may be white, brownish-white or occasionally grey; the termen is marked by a fine dark line and the veins are often darkened. In L.nickerlii the hindwing is usually silky white, but in ssp demuthi it may have brownish edges. Ssp demuthi cannot be reliably separated on hindwing markings, but the silkier texture is distinctive if looked for.
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D. Male genitalia
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1. Shape of aedeagus
This distinction is best seen, and can only be seen well, in lateral view of the aedeagus; and can be seen well without having to do much dissection. It is the easiest and probably best means of distinguishing the male genitalia of the two species. In L.testacea the concave (ventral) surface of the aedeagus is smoothly curved. In L.nickerlii it is straight in its basal half, then angled to form a hump. L.testacea may show a small swelling here but it is never pronounced and does not show the angulation seen in L.nickerlii. 2. Cornuti
In both species there is a small cluster of spine-cornuti, comprising several small spines and several larger spines. In L.nickerlii there are more spines than in L.testacea. Assessing their number can be problematic unless the vesica is everted - and the cut-off between small and larger cornuti is a matter of judgement. In specimens I have examined with the vesica everted L.testacea (5 specimens) has 10-12 spines (7 or 8 small, 3 or 4 larger); L.nickerlii (4 specimens) has 15-32 spines (8 to 25 small, 7 to 9 larger). The number of small spines (some of which are very small) that can be counted varies with the degree of separation of the spines that can be achieved in prep., so it is best to concentrate on the more robust spines, of which there are clearly more in L.nickerlii |
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3. Clavus
The clavus is at the postero-basal angle of the sacculus. It is more complex in L.nickerlii than it is in L.testacea. In L.nickerlii it is bulky with a broad apex and angled dorsally. This dorsal angulation means that it may not be seen well in a standard ventral view, but no other view displays it any more completely. It is however, fairly easy to determine. once experience is gained with both species, by viewing from several angles during dissection. In L.testacea the clavus is simple. (The difference between the species in separation of the two clavi in the image below is a preparation artefact).
The clavus is at the postero-basal angle of the sacculus. It is more complex in L.nickerlii than it is in L.testacea. In L.nickerlii it is bulky with a broad apex and angled dorsally. This dorsal angulation means that it may not be seen well in a standard ventral view, but no other view displays it any more completely. It is however, fairly easy to determine. once experience is gained with both species, by viewing from several angles during dissection. In L.testacea the clavus is simple. (The difference between the species in separation of the two clavi in the image below is a preparation artefact).
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4. Saccus
MBGBI10 states than L.nickerlii has a projection at the apex of the saccus which is absent in L.testacea. In my experience it is often absent in L.nickerlii, and even when it is present it may project dorsally and not be seen in a standard ventral view. However, I have not seen any specimen of L.testacea in which a distinct projection is present - so its presence may be regarded as a supporting feature for L.nickerlii. The male genitalia are Illustrated for both species in MBGBI10 p227; but these drawings incorrectly show L.testacea with the more complex clavus. The text states that in L.nickerlii the everted aedeagus has an extension which is absent in L.testacea. I have not been able to demonstrate this or to find any evidence supporting it. There may be a difference in the breadth of the cucullus (my impression is that it is slightly broader in L.nickerlii) but this is difficult to be sure of because the bulk of the sacculus makes it difficult to flatten the cucullus. The projection at the ventral angle of the cucullus appears to be variable in shape in both species. |
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E. Female genitalia
The only consistent difference between the species is in the shape of the posterior margin of the ventral lip of the ostium; which is concave in L.testacea, ~straight in L.nickerlii.
The only consistent difference between the species is in the shape of the posterior margin of the ventral lip of the ostium; which is concave in L.testacea, ~straight in L.nickerlii.
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Luperina dumerilii (Dumeril's Rustic)
Characterised by an obliquely elongate oval mark in the forewing and a sharply angled ventral projection from the cucullus in the male genitalia.
Characterised by an obliquely elongate oval mark in the forewing and a sharply angled ventral projection from the cucullus in the male genitalia.
Page published 08/02/2016 | revised 04/12/2024
