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.