Observations on the biology of Afrotropical Hesperiidae (Lepidoptera) with particular reference to Kenya. Part 10. Pyrginae, Carcharodini
Author
Cock, Matthew J. W.
text
Zootaxa
2016
4173
4
301
350
journal article
38068
10.11646/zootaxa.4173.4.1
235cd1e5-39f4-43b4-a65a-94daa8e45bec
1175-5326
256597
3E955EB2-79DE-462C-B3EE-E4AF334D1F61
Spialia ploetzi
Aurivillius, 1891
The
similarities described here between the life histories of
S. dromus
and
S. ploetzi
confirms
De Jong's
placement of
S. ploetzi
in the
dromus
group of
Spialia
(De Jong 1978)
.
The
type
locality of
S. p. ploetzi
is
Cameroon
(
Aurivillius
1891), and its range extends to
western Kenya
.
De Jong (1977) divided
S. ploetzi
into two subspecies:
S. ploetzi occidentalis
De Jong
(
Figure
23.1) from
western Africa
(
type
locality
Ghana
) and the nominate subspecies (
Figure
23.2) from
eastern Africa
; the dividing line between the two subspecies runs through
Cameroon
.
I have only encountered this species twice in
Kenya
: both times in
Kakamega
Forest, where the D267 crosses Ikuywa Stream. This species is restricted to the western forests and is scarce there.
Adult
behaviour.
I once found two males drinking at mud in
Kakamega
Forest (
Jan 1989
).
FIGURE 23.
Adults of
Spialia ploetzi
.
1
, female
S. ploetzi occidentalis
, collected as caterpillar on?
Triumfetta
sp., Forêt de Yapo, Côte d’Ivoire, 4 Dec 1988; adult 20 Dec 1988, MJWC 88/205A.
2
, female
S. ploetzi ploetzi
, collected as small caterpillar on
Triumfetta
sp., Douala, Cameroon, 16 Jun 1990; adult 15 Sep; MJWC 90/204.
Food plants.
Fontaine (1988) reared this species (as
S. rebeli
Higgins
, a synonym) on an unidentified food plant at Isiro, north-eastern DR Congo in 1960. Larsen (1981, 1991, 2005) describes a single sphecid wasp visually hunting for shelters of caterpillars of
S. ploetzi
on a
Triumfetta
sp. in a Lagos hotel garden, Nigeria. From his account, he does not seem to have reared voucher specimens, and given the habitat, it seems more likely that the caterpillars he observed were
S. dromus
, but I have not been able to discuss this possibility with him. Nevertheless, his observations that the individual wasp was hunting visually for bits of leaf under surface visible from above, that wasps bit through the leaf to reach the caterpillar inside (rather than lifting the flap), and that caterpillars that had folded their shelters under the leaf were not found, offer useful general insight to the roles of leaf shelters and predators.
I have not encountered caterpillars of this subspecies in
Kenya
, but have reared ssp.
occidentalis
from caterpillars collected on a
Triumfetta
sp. in
Côte
d'Ivoire (Figure 23.1) and ssp.
ploetzi
on the same food plant in
Cameroon
(Figure 23.2). Larsen (1991) reports my record of rearing ssp.
occidentalis
from
Triumfetta
sp. in
Côte
d’Ivoire and his from the same food plant in
Lagos
,
Nigeria
(although this may be an assumption on his part—see previous paragraph). Vuattoux (1999) found this subspecies
on
T. rhomboidea
in
Côte
d’Ivoire. I noted no significant difference between the caterpillars of the two subspecies, although the pupae differ in my small samples
Leaf
shelters.
A
leaf shelter of a young caterpillar of
S. p. ploetzi
in
Cameroon
(
MJWC
90
/204) was formed from a leaf lobe at the end of a major vein (Figure 24.1)
.
A
small flap was folded up each side of the vein to form the shelter, and feeding was in small patches (c.
1.5mm
diameter), four in the small area of leaf distal to the shelter, and 21 from the leaf basal to the shelter, arranged mostly along the main vein.
Of
the two mature leaf shelters of
S. ploetzi occidentalis
which I collected in
Côte d'Ivoire
(
MJWC
88
/205), one was a flap
25 x
13
mm folded upwards from the edge of the leaf, and the second was a large section of leaf
50 x
19
mm folded upwards
.
A
pupal shelter was distinctive, being formed from two small leaves about
35mm
long, one on top of the other; both leaves were evenly pierced by
1mm
holes over the entire surface except the margins where they were joined.
Caterpillar.
The caterpillar (Figure 24.2–3) is superficially similar to that of
S. dromus
, although the details of the setae on the head differ. In view of this similarity, all caterpillars apparently of
S. dromus
on
Triumfetta
spp. in
Kakamega
Forest should be carefully examined under magnification or reared as they may prove to be
S. ploetzi
.
FIGURE 24.
Shelter and caterpillars of
Spialia ploetzi
.
1
,
S. ploetzi ploetzi
shelter and feeding of n-2 caterpillar, collected as small caterpillar on?
Triumfetta
sp., Douala, Cameroon, 16 Jun 1990; photographed 17 Jun; MJWC 90/204.
2
,
S. ploetzi occidentalis
final instar caterpillar head, anterior view, collected on?
Triumfetta
sp., Forêt de Yapo, Côte d’Ivoire, 4 Dec 1988; photographed 6 Dec; pupated by 12 Dec; 22mm; MJWC 88/205A.
3
,
S. ploetzi ploetzi
final instar caterpillar, dorsolateral view; collected as #1; moulted to final instar 27 Jul; photographed 1 Aug; pupated 29 Aug; 17mm; MJWC 90/204.
The final instar of ssp.
occidentalis
(MJWC 88/205
A
) was
22mm
long (Figure 24.2). Head 2.2 x
2.6mm
wide x high; rounded, slightly indent at vertex; black, shiny, reticulate on epicranium, rugose on adfrontals and frons; each adfrontals with two round brown plaques in dorsal portion (the dorsal plaque was missing on one side); no setae on each side of epicranial suture, adfrontals, frons; on epicranium part of face a few very short or short pale, erect, narrow, linear setae; ventrally on face longer, erect, pale, simple setae; dorsally and laterally short to long black, twisted linear setae up to
0.6mm
long and
0.14mm
wide; posterior margin with pale setae similar to face. T1 with groove separating posterior third; marked in black and yellow (pale whitish on exuvia): rounded spot on anterior two-thirds of dorsum; quadrate spot on anterior two-thirds dorsolaterally; oval brown plaque subdorsally near anterior margin (lateral part of pronotum not visible in exuvia, but expected to have a similar plaque); with scattered short and long white, erect, narrow linear setae, slightly dilated and truncate at apex; legs black. Body greenish white; covered with short and long erect, pale, blunt setae on white bases; legs concolorous; spiracles inconspicuous.
The final instar of ssp.
ploetzi
(MJWC 90/204) was similar; head 2.4 x
2.5mm
wide x high; the very short, pale, simple setae extend to the frons and adfrontals but are almost absent from the centre of the face; two round brown plaques on upper part of each adfrontal; otherwise as ssp.
occidentalis
. The difference in very short setae on the head may be due to abrasion rather than of significance. The head of the penultimate instar of ssp.
ploetzi
was similar to that of the final instar; 1.7 x
1.7mm
wide x high; setae similar but less conspicuous, the black twisted linear setae up to
0.4mm
long and
0.08mm
wide.
Pupa.
The pupa of ssp.
occidentalis
was
13mm
long; no wax bloom; the cuticle transparent apart from faint brown bars subdorsally on the posterior margin of A4–A5, and brown markings on front of head and a vertical bar in the anterior and posterior halves of each eye; initially white (
Figure 25
), the pupa turned dark as it developed; short pale and light brown erect, simple setae; spiracles dark brown, conspicuous; spiracle T1 similar to other member of the genus with the posterior margin raised on a vertical wall, 0.52 x 0.70 x
0.36mm
wide x high x deep; small brown oval plaques subdorsally on anterior margin A2–A5; similar plaques ventral to spiracles on A4–A8. The pupal stage lasted 18 days.
In contrast, the pupa of ssp.
ploetzi
was extensively dark brown, apart from the wings, appendages and the abdomen laterally adjacent to the dorsum of the wings, and abdomen intersegmental regions; white, erect, simple setae; oval brown plaques as ssp.
occidentalis
; spiracles dark; spiracle T1 0.30 x 0.60 x
0.28mm
wide x high x deep.
FIGURE 25
. Pupa of
Spialia ploetzi occidentalis
, lateral view; collected as caterpillar on
Triumfetta
sp., Forêt de Yapo, Côte d’Ivoire, 4 Dec 1988; pupated by 12 Dec; photographed 13 Dec; adult 20 Dec 1988, MJWC 88/205A.
Discussion.
Larsen (unpublished) planned to raise
occidentalis
to species level, based on differences in the male genitalia, the patterns of the hind wing, and the absence of intergrading in the area between the extreme east of Nigeria and the Sanaga River, even when the two forms occurred in close proximity at different altitudes as little as
1km
apart.
My limited observations indicate that the caterpillars of
ploetzi
and
occidentalis
are very similar, but I found differences in the colouring of the pupae. However, without more material of both to assess individual variation in pupal colour, I conclude that it would be premature to suggest these cuticle colour differences are significant, given the amount of variation in pupal colour noted in some other species here. Certainly my observations are not incompatible with Larsen’s view, but with such limited biology observations to support this, I make no change to the current taxonomy.