Observations on the Biology of Afrotropical Hesperiidae (Lepidoptera) with particular reference to Kenya. Part 11. Heteropterinae
Author
Cock, Matthew J. W.
Author
Congdon, T. Colin E.
text
Zootaxa
2017
4226
4
487
508
journal article
37249
10.11646/zootaxa.4226.4.3
1bb0d3bf-fac9-4d4c-8d95-af3e2f12ddeb
1175-5326
265090
8753ADEF-2888-46CD-A6DE-6BDF9D3CE0DC
Metisella orientalis orientalis
Aurivillius, 1925
Aurivillius (1925)
gave the name
orientalis
to the 'race' of
M. metis
(Linnaeus)
(a
South
African species) which occurs ‘in the whole of
East
Africa as far as
Mt. Elgon’
(
Figure 7
). It is treated as a valid species of
Metisella
by
Evans (1937)
, who gave its distribution from the
Central
Highlands of
Kenya
through
Uganda
to
Zaire
,
Cameroon
, and
Nigeria
, and
South
through
Tanzania
to
Malawi
and
Zimbabwe
, in nine different infraspecific forms. Subsequently
Evans (1938)
described ssp.
elgona
from
Mt. Elgon
on the Kenya-Uganda border.
Larsen (2009)
clarified that Aurivillius’ treatment of the name
orientalis
should be considered an available name, not an unavailable infrasubspecific name, under the current rules of zoological nomenclature.
De Jong
(1976)
illustrates the male genitalia from
Kakamega
Forest,
western Kenya
.
Three forms are recorded from
Kenya
(
Evans 1937
):
orientalis
from the
Central
Highlands;
theta
Evans (wet season form of
orientalis
) from
Central
Highlands and
western Kenya
;
and
lamda
Evans from Maungu, near Voi. In
Tanzania
,
Evans (1937)
recognised form
zeta
Evans from
western Tanzania
,
kappa
Evans from the Usambaras (south to
Mozambique
)
; and form
lamda
from northern Tanzania.
Kielland (1990)
states that
M. orientalis
is found on ‘practically every mountain with evergreen forest’ in Tanzania and suggests every mountain range has its own form of
M. orientalis
. This is probably at least partially true in Kenya too.
Evans
distinguishes the wet season form
theta
as having the male hind wing underside brightly spotted, as are all females.
A
population which
MJWC
found in the
South
Nyambani Hills at
1650m
seems distinct from others, having the hind wing upper side marginal spots heavily marked in dark orange.
It
is possible that several species are involved here, and a revision of the whole genus may be undertaken by
R. de Jong. For
the present, the name
M. orientalis orientalis
seems adequate for all
Kenyan
and
Tanzanian
material pending the assembly and critical analysis of good series of material from key localities, supported by evidence from biology, behaviour and molecular studies.
Adults
and early stages are normally uncommon, only the odd specimen or two being found at one time.
However
,
TCEC
found that it can be common at
Mufindi
,
Tanzania
, especially late
January
to
March
, along streams through the forest.
FIGURE 7
. Adult
Metisella orientalis orientalis
collected as penultimate instar caterpillar on
Cenchrus trachyphyllus
(unconfirmed plant identification), Thomson’s Falls, Nyahurura, Kenya, 29 Dec 1990; adult emerged and photographed 30 Jan 1990; MJWC 90/125C.
1
, upper side;
2
, underside.
Food plants.
MJWC
reared this species three times in
Kenya
: a specimen from
Kakamega
Forest
(88/17B) was collected
on
Cenchrus trachyphyllus
(=
Pennisetum trachyphyllum
), and in captivity accepted another
Nairobi
grass; another specimen was collected
on
Panicum trichocladum
at
Kisii
(91/9) and in captivity fed
on
Panicum maximum
; and three specimens from the bottom of
Thomson's Falls
(90/125) were on a non-flowering grass which resembled (and could well have been)
Cenchrus trachyphyllus
.
Accordingly
,
Larsen
(1991)
gave the food plants as ‘various grasses’ and included
Pennisetum
, based on MJWC’s record from
C. trachyphyllus
.
At Mufindi
,
Tanzania
,
TCEC
found this species
on
Festuca africana
, but not on an adjacent
Setaria
sp.
Leaf shelters.
Caterpillars made shelters from rolled grass leaves, but no details were noted.
Caterpillar.
The penultimate instar caterpillar shown in Figure 8.1–2 has the head 1.4 x
1.6mm
wide x high (n=2); dark black-brown, the frons brown or translucent, the clypeus brown; shiny, weakly rugose on epicrania; shiny smooth adfrontals and frons, with shallow transverse grooves on adfrontals and to a limited extent on the ventrolateral frons; adfrontal suture not easily distinguishable, frontal suture defined by a row of small pits; covered with inconspicuous dark setae; pronotum a narrow black transverse band; anal plate black, shiny; body blue green, a diffuse white subdorsal line bordering the dorsal line; a more sharply defined white dorsolateral line.
The final instar (Figure 8.3–4) measured
15mm
when newly moulted and grows to at least
23mm
. Head similar in shape and appearance to some
Borbo
spp. (
Baorini
); 1.8 x
2.4mm
wide x high (n=4); rounded, relatively narrow, widest at stemmata, flattened at vertex; rugose; translucent dull matt green; broad black stripe from back of vertex anterolaterally to stemmata, narrower ventrally; posterior margin narrowly dark laterally and sometimes dorsally; one individual (91/9) had a small dark area on the epicrania adjacent to the top of the adfrontals; scattered short, fine, erect, pale setae. T1 translucent, unmarked, concolorous with body. Body translucent dull yellow-green; dorsal line darker, defined by a diffuse, pale, subdorsal line; stronger, white, dorsolateral line; anal plate rounded, shiny, green (not black as in previous instar); T2 with white anterior margin, joining the dorsolateral lines at each side; body with scattered, short, fine setae; legs concolorous; spiracles inconspicuous, white connected by a visible subcutaneous tracheal line; no wax glands. The fifth instar takes 13–16 days.
FIGURE 8
. Caterpillars of
Metisella orientalis orientalis
, Kenya [MJWC].
1
, penultimate instar, dorsolateral view with head in anterior view; collected as penultimate instar caterpillar on
Cenchrus trachyphyllus
(unconfirmed plant identification), Thomson’s Falls, Nyahurura, Kenya, 29 Dec 1990; photographed 29 Dec; moulted 6 Jan 1991; 15mm; MJWC 90/125C;
2
, as #1, detail of head and thorax;
3
, final instar collected as #1; photographed 31 Dec 1990, pupated 8 Jan; MJWC 90/125B;
4
, collected as penultimate instar premoult on
Panicum trichocladum
, Kisii; moulted and photographed 10 Feb; pupated 23 Feb; 15mm; MJWC 91/9.
The caterpillars from Mufindi which TCEC reared are similar but not identical (
Figure 9
). It can be seen that in the mature final instar caterpillar (Figure 9.2), the broad, black stripe on each epicranium is slightly narrower than Kenyan material, the subdorsal line on the body is double, the inner one being brighter and whiter; the posterior margin of the head is narrowly black (Figure 9.3) and there is a dark lateral spot on T1 which may be the spiracle (Figure 9.4). More material is needed to assess individual variation before assessing differences between populations.
Pupa.
A pupa (Figure 10.2) was found in situ at Thomson's Falls, Nyahururu, Kenya (MJWC 90/125A) in the rolled distal part of a leaf which drooped where there was feeding basal to this; the pupa was formed head up in the shelter, with a flimsy girdle at the posterior part of the thorax, and the cremaster attached to a silk cross bar; no white waxy powder. The pupa (
Figure 10
) is
21mm
long, and similar to others of the genus; elongate with smoothly contoured
2mm
frontal spike, which may be slightly upturned at apex,
1.3mm
wide at the base; posterior end rounded; light, dull green or yellowish green; dorsal line dark, extending onto frontal spike; thin, diffuse white subdorsal line bordering dorsal line from thorax to a little short of end of abdomen; wider, stronger, white dorsolateral line from thorax to end of abdomen; traces of a broken, dark dorsolateral line on head, continuing laterally on thorax and along dorsum of wings, with a noticeable small spot on anterior margin A1 adjacent to the hind wing; A3–A7 traces of a double pale lateral line; spiracles all inconspicuous. The developing adult colour and wing markings are visible as the pupa matures. Pupal development takes 11-13 days, and adult emergence when noted was in the morning.
FIGURE 9
. Final instar caterpillar of
Metisella orientalis orientalis
, collected on
Festuca africana
, Mufindi, Udzungwa Mountains
, Tanzania [TCEC].
1
, dorsal view, 20 Mar 2004;
2
, dorsal view, 20 Mar 2004;
3
, prepupa, dorsal view, 23 Mar 2004;
4
, detail of head of prepupa, anterior view, 23 Mar 2004.
FIGURE 10
. Pupae of
Metisella orientalis orientalis
, Kenya [MJWC].
1
, collected as final instar caterpillar on
Cenchrus trachyphyllus
,
Kakamega
Forest, 26 Feb 1988; pupated 7 Mar; photographed 8 Mar 1988; adult 18 Mar; 21mm; 88/17B;
2
, collected as pupa on
Cenchrus trachyphyllus
(unconfirmed plant identification), Thomson’s Falls, Nyahurura, Kenya, 29 Dec 1990; photographed 29 Dec; adult 10 Jan 1991; 21mm; 90/125A.
The pupa from Tanzania (
Figure 11
) was a slightly brighter green, and the dark markings more contrasting; otherwise very similar.