Africa
Igor Ya. GRICHANOV
Grichanov, I.Ya. Gigantosciapus (Diptera: Dolichopodidae),
a new genus from Tropical Africa
Gigantosciapus, a new genus of the dolichopodid subfamily
Sciapodinae is described. Catalogue and a key to 11 species
of the genus including G. oldroydi sp.n. from Cameroun are
given.
I.Ya. Grichanov, All-Russian Institute of Plant Protection,
Podbelskogo 3, St.Petersburg-Pushkin, 189620, Russia.
Key words: Diptera, Dolichopodidae, Gigantosciapus gen.n.,
Tropical Africa
Introduction
Beautiful and large sized species (from 7 to 14 mm, with length of
antenna upto 5 mm), included here into the new genus were originally
described within the old broad concepts of Psilopus Meigen, Chrysosoma
Guerin-Meneville and Megistostylus Bigot. Parent (1933) gave a key to
5 species of the Group I inside the genus Chrysosoma. Two of them as
well as 3 new related species were included by Vanschuytbroeck (1966)
into the key to the species of Megistostylus. Bickel (1994)
synonymized Megistostylus with Chrysosoma, but most Afrotropical
species were transferred to Plagiozopelma Enderlein. Bickel listed 10
species of the "gemmarium Group" of Chrysosoma and supposed that they
should be referred to Plagiozopelma or made a separate genus.
Most of those species were briefly or incompletely described. Some
of them are known from females, others - only from males. Authors in
their descriptions often omitted important characters regarded now as
having generic level. While processing unidentified material from the
collection of the Natural History Museum (London), a male and a female
of the new species of "gemmarium Group" were found, that permitted to
establish the new genus of Sciapodinae.
All the species of the new genus are known from the tropics of
West and Equatorial Africa as well as from Madagascar. In this paper a
first attempt to draw up a key to all known species of the genus is
made.
Holotype and paratype of the new species are conserved in the
Natural History Museum (London).
Gigantosciapus gen.n.
Type-species: Gigantosciapus oldroydi sp.n., here designated
Description. Head wider than high; vertex deeply excavated.
Occiput not concave, grey pollinose. Frons slightly concave, shining
metallic, narrow, one fourth as wide as head width. One pair of strong
ocellar; proclinate vertical bristles absent in both sexes; lateral
frons bare. Two pairs of strong postvertical setae present, not in
line with postocular series. Upper postocular bristles black, in one
row. Ventral postcranium covered with irregular pale hairs. Eyes bare,
not joined across face. Face and clypeus narrow, from 1/5 to 1/10 of
head width, female face wider, with slightly indicated suture in the
middle of face, densely pollinose; clypeus bulging, come down eyes,
but adjacent to margin of eyes. Cheeks undeveloped. Palpi short,
proboscis one third as long as head height. Antenna mostly yellow,
nearly thrice as long as head height, inserted in the upper third of
head; scape bare, often swollen, pedicel sphaeroidal, with short
subapical setae, without appendices. First flagellomere bare, very
long, shorter in females, at least thrice as long as its height.
Arista apical, long, simple, bare.
Thorax mostly yellow. Mesonotum sometimes partly metallic; 1 ph,
2 ntpl, 1 sa, 1 pa. Two pairs of strong posterior dorsocentral
bristles, with a few hairlike setae in front of them, not sexually
dimorphic; short biseriate acrostichals in anterior half of mesonotum.
Scutellum with two strong bristles and usually with one pair of
marginal hairs. Postnotum developed. Propleuron without setae.
Legs mostly yellow, usually simple. Fore coxa with sparse hairs
and 2-3 apical bristles, middle and hind coxae with strong bristle.
Femora without strong bristles or spines. Tibiae and first tarsomeres
with developed bristles in both sexes. Male fore tibia and
basitarsomere often ornamented.
Wings elongate, slightly darkened, not sexually dimorphic. Veins
simple. Costa reaches M1 before apex; M1 and R4+5 strongly converged;
M1 almost straight, M2 straight, very short; crossvein m-cu straight
or slightly convex, placed in apical third of wing, making a right
angle with M vein. Anal vein usually reduced. Anal lobe small or
undeveloped. Anal angle lost in both sexes. Lower calipter often
reduced in both sexes.
Abdomen long and thin, cylindrical, partly yellow-brown,
unmodified segments together nearly twice as long as mesonotum. Male
7th abdominal tergit short but well developed. Epandrium attached to
the tip of 7th tergit. Hipandrium arising from the base of epandrium;
aedeagus dorsally with 1 or 2 denses. Surstylus and cercus
comparatively long and broad, simple; epandrial lobe with numerous
setae. Oviscapt of Austrosciapus type.
Diagnosis. The new genus has some similarities with Plagiozopelma
and Chrysosoma as well as with Austrosciapus, Amesorhaga and Tenuopus
(Neurigoninae), but has many differences such as follows. Vertical
setae or hairs absent in both sexes; two pairs of strong postvertical
setae placed far from line of postocular series. Face and frons
narrow. First flagellomere very long, tapering into the long apical
arista. Acrostichals short and weak; 2 strong dorsocentral bristles
and 3 or 4 weak hairs anteriorly in both sexes. All tibiae and
basitarsomeres usually with strong bristles in both sexes. Wing vein
m-cu straight or slightly convex, anal lobe and lower calipter usually
reduced. Aedeagus dorsally with a few denses; surstylus greatly
developed; epandrial lobe prominent, but not prolonged and curved,
with numerous setae; cercus and surstylus long and broad, simple.
Gigantosciapus should be included in the key to world genera of
Sciapodinae (Bickel, 1994) as follows:
11. Crossvein m-cu straight or slightly convex, pleura usually
yellow, legs elongate, male fore leg often ornamented; cercus
unbranched....................................................11a
- Crossvein m-cu sinuous; tibiae often with major setae; cercus
usually deeply forked..........................................12
11a. Vertical setae absent in both sexes, acrostichals short; all
tibiae and basitarsomeres with strong bristles in both sexes....
..................................................Gigantosciapus
- Verticals weak in males and strong in females, 2 or 3 long
acrostichal setae present; male fore tibia usually with strong
curved posterior subapical seta, otherwise legs usually devoid
of strong setae................Amblypsilopus pallidicornis Group
Etymology. Gigantosciapus is formed adding the Greek prefix
"giganto-" referring to large size of including species to Sciapus,
the type-genus of the subfamily.
Included species (for references see Dyte & Smith, 1980):
africanus Parent, 1933:16 (Chrysosoma) - Zaire, n.comb.
anomalipes Parent, 1935:112 (Chrysosoma) - Zaire, Ghana, n.comb.
decellei Vanschuytbroeck, 1966:202 (Megistostylus) - Ivory Coast,
n.comb.
gemmarius Walker, 1849:645 (Psilopus) - Sierra Leone, Congo, Ghana,
Zaire, Ivory Coast, Liberia, Cameroun, n.comb.
= fulvicinctus Bigot, 1891:372 (Psilopodius)
inversus Curran, 1927:249 (Chrysosoma) - Sierra Leone, Liberia, n.comb.
kamerunensis Becker, 1927:27 (Chrysosoma) - Cameroun, Zaire, Madagascar,
n.comb.
meyeri Vanschuytbroeck, 1962:353 (Megistostylus) - Nigeria, n.comb.
oldroydi sp.n. - Cameroun
pseudogemmarius Parent, 1934:118 (Chrysosoma) - Congo, n.comb.
saegeri Vanschuytbroeck, 1959:9 (Megistostylus) - Zaire, n.comb.
tuberculatus Curran, 1927:246 (Chrysosoma) - Ghana, Ivory Coast,
n.comb.
Gigantosciapus oldroydi sp.n. (Fig. 1)
Holotype. Male, B. Cameroons, Nyasoso, 3.XI.1949, H. Oldroyd.
B.M. 1950-2. Paratype. Female with the same label as holotype.
Description. Frons shining metallic blue-green, bare, longer than
wide. Two pairs of postvertical bristles present on the back slope of
the vertex. Face grey pollinose, narrow, somewhat narrowed in the
middle; ratio if its width in the middle to epistome to clypeus length
- 10 : 43 : 33. Clypeus bulging, beak-like, coming down eyes, but
adjacent to margin of eyes except apex. Palpi and proboscis yellow,
not very long, covered with small light and dark hairs, palpus also
with a pair of black bristles. Scape and pedicel yellow; first
flagellomere except base and arista brown; pedicel with a ring of
short setae, first flagellomere slightly pubescent, tapering, 7 times
as long as heigh at base. Arista apical, bare, simple. Length ratio of
scape to pedicel to first flagellomere to arista (first and second
articles) - 11 : 6 : 45 : 85 : 180.
Thorax mostly yellow, hind half of mesonotum and scutellum mostly
metallic blue-green, other parts of mesonotum brownish as well as
stripe coming down of haltere. Two dorsocentral bristles with at least
5 hair-like setae in front of them; a few short acrostichals in two
rows, restricted in anterior part of mesonotum. Scutellum with two
strong bristles and two very short hairs from the outside.
Coxae and trochanters mostly yellow, hind coxa partly brownish;
fore femora and basal half of middle femora yellow, fore tibia, fore
basitarsomere and middle tibia brown; other podomeres broken. Fore
coxa from the front with short dark hairs and with two or three black
apical bristles. Middle coxa from the front with a few dark hairs and
a few longer black apical hairs. Hind coxa with one long black
external bristle, with several dark apical hairs. Fore and middle
femora with short fine dark ventral hairs, usually shorter than femora
diameter. Fore tibia with three dorsal and three ventral bristles.
First tarsomere with one strong posteroventral bristle in apical fifth
and two hairlike posteroventral setae in the middle. Length ratio of
fore coxa to femora to tibia to basitarsomere - 6.2 : 7.8 : 12.0 :
8.6. Middle tibia with three strong dorsal, three posterior, four
ventral, three or four apical bristles. Length ratio of middle coxa to
femora to tibia - 3.5 : 12.0 : 18.5. Hind legs broken.
Wings slightly darkened, brownish between C and R4+5 in apical
third, veins brown. Costa with short simple setulae, posterior border
with short hairs. M1 and M2 strongly diverged; crossvein m-cu slightly
convex, forming right angle with M1+2. Anal vein and lobe absent.
Haltere stem long and thin, yellow, knob brownish. Lower calipter
reduced, without setae.
Abdomen thin and long, cylindrical, with short dark hairs and
black bristles. 1st segment mostly yellow-brownish with metallic
reflection from above, other segments metallic bronze-green with mat
black bands in basal third. 7th tergum with four pairs of strong
marginal bristles; 7th sternum well developed, with short hairs.
Hypopygium black-brown, attached to the tip of 7th segment. Hypandrium
with left lateral arm, fused with long hypandrial hood, which
broadened apicad. Aedeagus with two dorsal angles. Epandrial lobe
prominent, with 10 - 11 long setae. Cerci broken. Surstylus simple,
strongly sclerotized, broadened distad, with small apicodorsal dens
and a few apicodorsal setae.
Female. Similar to male except lacking male secondary sexual
characters, otherwise as follows: frons shining metallic blue-violet,
bare; face greyish-white pollinose, ratio if its width in the middle
to epistome to clypeus length - 15 : 37 : 33. First flagellomere
thrice as long as heigh at base. Length ratio of scape to pedicel to
first flagellomere to arista - 11 : 7 : 24 : 260.
Mesonotum more widely yellow than in male. Middle and hind femora
yellow in basal half, orange-brown in apical half. Fore tibia, fore
basitarsomere and middle tibia except apical third yellow-brownish;
middle tibia in apical third, hind tibia, middle and hind
basitarsomeres whitish-yellow; apical segments of tarsi brown. Middle
and hind femora with a few apicoventral hairs. Fore tibia with three
dorsal, three ventral, one or two apical setae; fore basitarsomere
with one dorsal, three antero-ventral and 3 postero-ventral setae.
Length ratio of fore coxa to femora to tibia to tarsus (segments from
first to fifth) - 6.8 : 8.8 : 10.5 : 7.0 : 2.3 : 1.6 : 1.5 : 1.0.
Middle tibia with five antero-dorsal, three or four postero-dorsal,
three or four ventral and four or five apical bristles. Middle
basitarsomere with two antero-dorsal, one postero-dorsal and one
ventral short setae. Length ratio of middle coxa to femora to tibia to
tarsus (segments from first to fifth) - 3.9 : 12.0 : 17.5 : 9.2 : 2.5
: 1.7 : 1.1 : 0.6. Hind tibia bears upto eight antero-dorsal, eight
postero-dorsal and eight ventral bristles. Hind basitarsomere with one
or two dorsal, one or two ventral short setae, with one basal
postero-ventral strong bristle. Length ratio of hind coxa to femora to
tibia to tarsus (segments from first to fifth) - 3.0 : 14.0 : 19.5 :
8.2 : 2.8 : 1.9 : 1.0 : 0.7.
Wing the same as in male. Ratio of parts of costa between R2+3 and
R4+5 to those between R4+5 and M1 - 30 : 4. Ratio of crossvein m-cu to
apical part of M1+2 (fork-handle) to apical part of CuA - 70 : 117 :
25. Anal vein and lobe absent. Lower calipter reduced.
Venter pale; oviscapt of Austrosciapus type (Bickel, 1994: fig.
3e), ninth hemitergit with simple setae, without acanthophorites;
cercus long, with one long and one shorter apical setae.
Length: body 9.1 mm; body with antenna 13.6 mm; wing-length 8.8
mm; wing-width 2.5 mm.
Distribution: Cameroun.
Diagnosis. Gigantosciapus oldroydi is close to G. pseudogemmarius,
but differs by shorter first flagellomere, which half as long as face
height in male, and by other characters. Male cannot be associated
with G. kamerunense because of first flagellomere partly brown and
femora partly dark. It also cannot be associated with G. meyeri, G.
decellei and C. tuberculatus because of absense of lower calypter
cilia, and presence of long femoral hairs. It differs from G.
anomalipes and G. saegeri in setation of fore tibia and first
tarsomere. It differs also from G. africanus by mostly yellow middle
femora, and from G. gemmarius - by partly yellow fore tibia, partly
brownish hind coxa, entirely dark 3d-5th abdominal segments and mostly
brown first flagellomere.
Key to known species of Gigantosciapus
1. Antenna entirely yellow, legs entirely pale..G.kamerunensis Becker
- First flagellomere at least partly brown-black...................2
2. Fore basitarsomere enlarged or flattened.........................3
- Fore basitarsomere not enlarged..................................5
3. Fore femora without long ventral hairs....G.meyeri Vanschuytbroeck
- Fore femora with long ventral hairs..............................4
4. Lower calipter with black cilia.........G.decellei Vanschuytbroeck
- Lower calipter with yellow cilia.............G.tuberculatus Curran
5. First flagellomere brown with yellow base, 7 times as long as
high at base; coxae yellow, hind coxa partly brownish; fore femora
and basal half of middle femora yellow, apical half of middle
femora, fore tibia except base, fore basitarsomere and middle
tibia brown; fore tibia with three dorsal and three ventral
bristles; fore basitarsomere with one strong posteroventral
bristle in apical fifth and two fine posteroventral setae in the
middle; lower calipter reduced, without cilia.....G.oldroydi sp.n.
- Other combination of characters..................................6
6. Middle tarsus ornamented.........................................7
- At least 3d and 4th tarsomeres of middle tarsus simple...........8
7. Fore basitarsomere with a bristle in the middle and a bristle in
basal fifth....................................G.anomalipes Parent
- Fore basitarsomere with a bristle in the middle and a bristle in
apical fourth; second tarsomere of fore tarsus bulbar at base.....
..........................................G.pseudogemmarius Parent
8. Fore tibia with six long posterior bristles in apical part; male
cercus broad.............................G.saegeri Vanschuytbroeck
- Fore tibia with short bristles or fine cilia.....................9
9. Posterior tibia brown at least in basal eighth, white beyond the
middle...........................................................10
- Posterior tibia entirely whitish or only somewhat yellowish basally
.................................................................11
10. Hind femora brown.......................G.inversus Curran (female)
- Hind femora mostly yellow, black in apical fourth.................
................................................G.gemmarius Walker
11. Middle and hind femora entirely black; first flagellomere
entirely black..................................G.africanus Parent
- Middle femora yellow-brown, first flagellomere partly pale
(females).......................................................12
12. Fore basitarsomere at most with one bristle on either side........
...............................................G.anomalipes Parent
- Fore basitarsomere at least with three bristles on either side of
lower surface...................................................13
13. Fore basitarsomere with six or seven long bristles on either
side of lower surface........................G.tuberculatus Curran
- Fore basitarsomere with only three bristles on either side of
lower surface...................................................14
14. First flagellomere at least as long as face height................
..........................................G.pseudogemmarius Parent
- First flagellomere at most half as long as face height............
..................................................G.oldroydi sp.n.
Acknowledgement
I am sincerely grateful to Dr Brian Pitkin for his kindness in
giving me the opportunity to study the collection of the Natural
History Museum (London).
References
Bickel D.J. 1994. The Australian Sciapodinae (Diptera:
Dolichopodidae), with a review of the Oriental and Australasian
faunas, and a world conspectus of the subfamily. - Rec. Austral.
Mus., Suppl. 21: 1-394.
Dyte C.E. & Smith K.G.V. 1980. Family Dolichopodidae. In R.W.
Crosskey (ed.). Catalogue of the Diptera of the Afrotropical Region.
Brit. Mus. (Nat. Hist.), London, p. 443-463.
Parent O. 1933. Etude les Dipteres Dolichopodides du Musee du
Congo (Tiervueren). - Rev. Zool. Bot. Afric., 24, 1, p. 1-49.
Vanschuytbroeck P. 1966. Dolichopodidae de la Cote d'Ivoire.
Megistostylus decellei sp.n. - Rev. Zool. Bot. Afric., 74, 1-2, p.
200-204.
Remark under figure
Fig. 1. Gigantosciapus oldroydi sp.n., hypopygium.