Description of the last instar larva of Agriocnemis f. falcifera Pinhey, 1959 (Zygoptera: Coenagrionidae)

5 Pages·1996·1.2 MB·English

by  Domenico, M Di

Odonatologica25(3): 297-301 SeptemberI, 1996
SHORT COMMUNICATIONS
Description of the last instar larva of
Agriocnemis f. falcifera Pinhey, 1959
(Zygoptera: Coenagrionidae)
M.Di Domenico¹,M.J. Samways² and G. Carchin¹i
1 Dipartimentodi Biologia,University “Tor Vergala”,
Via della Ricerca Scientifica,1-00133 Roma, Italy
2 Invertebrate Conservation Research Centre, DepartmentofZoology and Entomology,
University ofNatal, P/Bag X01, Scottsville 3209, Pietermaritzburg,South Africa
Received October 12, 1995/ReviewedandAccepted January 15, 1996
Ultimate instar larva ofboth sexes, from Pietermaritzburgand Durban,South
Africa, is for the firsttime described, illustrated and comparedwith the African
and Asiatic congeners.
INTRODUCTION
ThegenusAgriocnemis is widely distributedthroughAfrica,AsiaandAustralia.
Seventeenspecies occurinAfrica(DAVIES &TOBIN, 1984),althoughthesystem-
atic status of some oftheseis controversial.Five species areknown fromSouth
Africa: A. exilis S61ys, 1872,A.falcifera Pinhey, 1959,A. gratiosa Gerstaecker,
1891,A.pinheyi Balinsky, 1963,andA.ruberrimaBalinsky, 1961(PINHEY, 1984).
A.pinheyi is theonly South African species whoselarval morphology is well
known(CARCHINIetal., 1995).Among theotherAfricanspecies, thereis only a
poor description of A. pygmaea(Rambur, 1842)from the Seychelles (PINHEY,
1974)andfromIndia(KUMAR, 1973).DUMONT(1991)has illustratedthepalpus
of.A.sania(Nielsen, 1959),probably fromIsrael.However,A. saniaisconsidered
byPINHEY(1974)andDAVIES&TOBIN(1984) tobeasubspecies ofA.pygmaea.
Even among theAsian species, very fewoftheirlarvae havebeen described: A.
femina (Brauer, 1868) by LIEFTINCK (1962) and by CHOWDHURY & MIAH
(1990); A. corbetiKumar & Prasad, 1978by KUMAR & PRASAD (1978); A
lacteolaSelys, 1877by CHOWDHURY &MIAH(1990).
A.falcifera occurs instillwatersonly inSouthAfrica.A.f.falciferaFinney, 1959
isknownfromKwaZulu-NatalandA.f. transvaalicaPinhey, 1974fromTransvaal
298 M.Di Domenico, M.J. Samways& G. Carchini
(Mpumalango). Themorphology ofthelast
instarlarvaofA.f.falciferais describedhere
forthefirsttime.
METHODS
The larvae were collected inthe field and reared
through to emergence in the laboratory. Species
determinationswere fromtheteneralimago. Exuviae
were stored in 75% ethyl alcohol, and drawn using
a microscopeand camera lucida (up to 100 x mag-
nification). All measurements were to the nearest
0.1 mm, using a micrometric eyepiece.
CORBET’S (1953) terminology for, the labium
was adopted, and abdominal segments are indicated
as S1...S10.
MORPHOLOGICAL DESCRIPTION
Material. - I last instar 3 larva. National
Botanical Gardens, Pietermaritzburg, 12-III-1992;
- 1 lastinstar 9 larva, Kenneth Stainbank Nature
Reserve, Durban, 29-XII-I992,Gael Whiteley leg.
Fig. 1. Agriocnemisf.falcifera: exuviae
Body as typicaloftheAgriocnemidinae
(Fig. 1), i.e. similar to the other Coenagrionidae, but smaller. Surface of body
smooth, glabrous, pale brown, yellowish intheexuviae, withno bands, spots or
other colourpatterns.
Head pentagonal, with postocular lobes rounded,andlarge eyes. Antenna7-
-segmented, the third segment being the longest. Seventh segment shorter than
halfthelength of thesixth (Fig. 2a). Prementumpentagonal in shape. Premental
setae 5+5.Arow of6-10spiniform setae on thedistalhalfofthelateraledges of
prementum, notreaching the
articulationwithpalpi. Distal
margin ofprementum finely
crenulated (Fig. 2b). Palpus
typical ofthe family. Palpal
setae5&5or5&4.Movable
hook stout and short, not
longer than the palpal setae.
Distalmargin ofpalpus with
6 strong, rounded teeth, the
internal one being the long- Fig. 2. Agriocnemisffalcifera: (a) antenna;- (b) mask; -
est.Distal halfoftheinternal (c) palpus.
Larva ofAgriocnemisffalcifera 299
edge ofpalpus crenulated(Fig. 2c).
Thorax glabrous, wing sheath
reaching the halfofS4. Legs long,
withvery smallspines andfew long,
thinsetae onfemurandtibia.Pecti-
nateandtridentatesetaeontarsusand
distalend oftibia, the pectinate se-
tae moreabundantontarsus.
Abdomen conical, witharow
of spiniform setae on the lateral
carinaofsegments S5-S9(Fig. 3a).
Ovipositorwell developed,reaching
thehalfofS10,witharow ofspines
ontheventraledge. Strongspiniform
setae on distal margins and dorsal
surface ofthe last abdominal seg- Fig. 3. Agriocnemisf.falcifera: (a) abdomen;—
ments. Cerci short yet distinctive (b) last abdominal segments, lateral view; - (c)
(Fig. 3b). Caudal lamellaelong and lateral lamella.
pointed, wider in the distal half. Principal tracheae slightly decentralised and
straight, secondary tracheaewide,ramified, emerging fromthefirstwith anangle
near to90°intheproximal third,acute more distally(Fig. 3c). Abreaking lineon
lamellaeinsertiononS10. Nospotsor transverse bands on lamellae.
For measurements see Table I.
DISCUSSION
Wehavecompared themorphol-
Table I
Measurements (in mm) ofa male and a female speci- ogy of A.f.falcifera withthe de-
menofAgriocnemisf.falcifera scribedAfricanandAsianspecies.
A.f.falcifera shows most ofthe
Character 6 2 characteristic featuresoftheother
Agriocnemidinae. Its dimensions
Total body length 9.2 9.2
Head width 2.4 2.9 are very small (body length 9.2
Distance between antennaeinsertions 0.8 0.8 mm), intermediatebetweenthestill
Antenna length 1.7 1,7 smaller A. lacteola(8.4 mm) and
Wing-sheath length 2.5 2.5 thelarger A.femina (11.03). Inits
Hind femur length 2.2 2.6 even colourpattern, A.f.falcifera
Hind tibia length 1.8 2.3
Hind tarsus length 0.8 0.8 differsfrombothA.pygmaeaand
Mask length 2.0 2.0 A. pinheyi, which both have dis-
Mask width 1.6 1.6 tinctlongitudinal stripes along the
Median lamella length 5.7 5.7 body.
Lateral lamella length 6.2 6.2
The shape of the head, with
300 M.DiDomenico, M.J. Samways &G. Carchini
roundedpostocular lobes issimilartothoseofall otherspecies, withexception of
A. corbeti. which haspostocular lobesthat are pointed andtriangular in shape.
Theeyes, as wellas themaskandthenumberofthepremental setae,are similar
in all thedescribed species. Thepalpal morphology is also similar in allspecies,
withtheexception ofA.saniafromIsrael, whosepalpusshows a verylong internal
toothand a much shorter movable hook (DUMONT, 1991). This feature distin-
guishes A. saniafrom all the otherAgriocnemis spp. larvae sofardescribed, in-
cludingA.pygmaeafromtheSeychelles (considered conspecific by PINHEY(1974)
andDAVIES&TOBIN (1984)).
The pectinate setae on tarsi andtibiaeofA.f.falcifera are unusual. The same
featureoccurs inA.pinheyi (CARCHINI etal., 1995), inA. corbeti(KUMAR &
PRASAD, 1978) and in A. pygmaea (KUMAR, 1973), yet they have not been
describedfromotherAgriocnemis larvae. Thismay possibly bebecause thevery
smallsizeofthese setae,whichare only visiblewith a goodstereomicroscope.
ThecaudallamellaeofA.f.falcifera havestrong andnumerous tracheae, as in
Ischnura sp.,andclosely resembling thoseofA.femina andA. lacteola,butnotA.
pinheyi. A.pinheyi alsohasnobreaking lineatthelamellaeinsertionsasdoesA./
falcifera.Also, A.f.falciferahasnospotsor stripes onthelamellae,thus differing
from some Asian species such as A. lacteola, A. corbetiand Agriocnemis sp.
(KERDIPIBULE etal., 1979).
Inconclusion, thestripedpattern alongthebody, thetransverse bandsacross the
lamellae and the shape ofthe postocular lobes appear to be the only characters
really helpful fordiscerning thedifferentspecies, although nooneoftheAgriocne-
misspecies so fardescribedshow allofthethreecharacters, andnooneofthelatter
is exclusiveofone species.
ACKNOWLEDGEMENTS
The study was financed by grants from the Italian M.U.R.S.T. (Programma: Popolamento
Animale del Mediterraneo Occidentale) and C.N.R, (to G. Carchini) and the Foundation for
Research Developmentandthe UniversityofNatal Research Fund (toM.Samways). Ms PAMELA
SWEET kindly processed the manuscript.
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