Pampsilota dahomeyanus Goergen, Koch & Liston, 2017

Liston, Andrew D., Goergen, Georg & Koch, Frank, 2017, Revisions of the Afrotropical genera of Argidae and species of Pampsilota Konow, 1899 (Hymenoptera, Tenthredinoidea), Deutsche Entomologische Zeitschrift 64 (1), pp. 1-25 : 8-11

Pampsilota dahomeyanus Goergen, Koch & Liston sp. n.

Female.

Figures 15-18 , 47-48

Head black; labrum yellow. Thorax yellow with following black: mesoscutum except for a small lateral spot on lateral lobe adjacent to tegula; mesoscutellum and metanotum; dorsal and ventral margin of propleuron. Legs yellow; mesotibia very narrowly and metatibia broadly ringed blackish apically; mesotarsomeres with black apex, metatarsomeres black, with basal half of metabasitarsomere yellow. Wings bicoloured: basal half flavescent, apical half and intercostal area infuscate; substigmal spot fuscous and small; stigma, subcosta and venation in apical half black; costa and venation in basal half yellowish. Abdomen yellow.

Head parallel-sided behind eyes. Antenna 1.4 × as long as maximum head width; flagellum enlarged towards apex, quadrangular in cross section, interior surface with sharply compressed longitudinal carina, other longitudinal carinae more weakly compressed. Eyes slightly converging towards clypeus. Anterior margin of the clypeus with shallow circular emargination, supraclypeal area slightly rounded, protruding up to base of interantennal carinae, interantennal carinae obtusely ridged, very slightly converging below, extending about to the level of ventral margin of torulus. Frons, supraclypeal area and clypeus moderately densely punctate, shiny; vertex and gena scattered micropunctate, shiny; pubescence yellowish. Anterior half of mesoscutum densely punctate, weakly shiny; posterior half nearly impunctate, shiny; pubescence similar to that on head. Abdomen smooth and shiny. Valvulae 3: Figs 15 , 16 . Lancet with about 19-20 serrulae: Figs 17 , 18 .

Length: 7.8-9.0 mm.

Male.

Figures 19 , 49-50

Coloration similar to female except for a more or less large yellowish patch on clypeus and supraclypeal area. Sometimes mesoscutellum yellow only medially and on posterior half. Mesotibia entirely, mesotarsus nearly entirely yellow; metatarsomeres black ringed apically. Wings slightly infuscate throughout; stigma, subcosta and venation blackish, only costa yellowish.

Head slightly narrowed behind eyes. Antenna 1.9 × as long as maximum head width; flagellum scarcely enlarged towards apex, scarcely flattened apically, slightly triangular in cross section; interior surface with sharply compressed longitudinal carina, other longitudinal carinae much more weakly compressed. Other characters as for female. Penis valve: Fig. 19 .

Length: 7.3-7.7 mm.

Type material.

Holotype: ♀. Labels: "Benin, Cotonou, on Lannea nigritana , 3.X.2014, leg.: G. Goergen"; "Holotype, Pampsilota dahomeyanus n. sp. ♀, det.: F. Koch, 2016" [red] (MFN). Paratypes [all from Benin, leg. G. Goergen]: 20 ♂♂; 4 ♀♀: same data as holotype (MFN, SDEI, USNM). 2 ♂♂; 1 ♀♀: Pobè-Forest, 6°57 ’46.7” N 2°40 ’26.7” E, on Lannea nigritana , 26.08.2016 (MFN). 2 ♀♀: Bohicon, 7°11 ’29.7” N 2°04 ’08.3” E, on Lannea nigritana , 07.2014 (MFN, SDEI). 2♂♂: Pahou, forest area, 05.07.2010 (MFN). 3♂♂, data as preceding, except 11.2014, on Lannea nigritana (MFN). 1♂ Womè, 11.2014 (MFN). 11♂♂; 9 ♀♀: Calavi IITA, ex larvae collected from and reared on Lannea nigritana , 11.2014, (IITAC). 14♂♂: Cotonou, 6°22 ’59.4” N 2°13 ’32.0” E, on Lannea nigritana , 05.10.2010 (IITAC). 3♂♂; 3♀♀: Cotonou, on Lannea nigritana , 05.10.2014 (IITAC).

Larva.

Figures 51-55 .

Individuals of two instars were examined in detail: GBIF GISHym 21229, total length 13mm, head capsule width 1.4mm; GBIF GISHym 21236, total length 6mm, head capsule width 0.9mm. Mature larvae reach a length of about 25 mm. All examined instars extremely similar in coloration except that the abdominal prolegs are pale in later instars (Fig. 51 ), and blackish in younger larvae (Fig. 52 ). The trunk is mainly green (Fig. 53 ). They possess the ground-plan characters of Argidae as given by Lorenz and Kraus (1957): one antennomere, abdominal segments 2-9 with 3 dorsal annulets, and tarsus of thoracic legs (Fig. 54 ) with large empodium.

Head with frons mainly dark, and extensive partly confluent black patches on parietal region and vertex (Figs 51 , 55 ). Mandible with 2 setae. Maxillary palp with 6 setae on outer surface. Clypeus with 2 setae. Anterior edge of labrum with fringe of about 12 setae directed in same plane as labrum; two longer setae arise near the centre and are directed outwards. Frons with about 35 short setae, mostly shorter than diameter of antennomere. Rest of upper head moderately setose; setae mostly shorter than diameter of antennomere. All setae fine and pale. Labrum without central groove.

Thoracic legs with six articles (Fig. 54 ). Claw with strongly developed basal lobe. Coxa and trochanter black; distal articles brown. Cervical sclerite black. Thoracic subspiracular and surpedal lobes strongly projecting; black, including setae. Spiracular area of prothorax with three black markings.

Entire surface of trunk with numerous very short, fine, pale setae. On dark-pigmented areas of thorax and abdominal segments 1, 2 and 10, setae are darker and longer. All three dorsal annulets of meso- and metathorax and abdominal segments 1-2 with row of small, dark-pigmented glandubae (Fig. 52 ). Prothorax with fewer small glandubae, but paired medial black markings larger than on other segments (Fig. 52 ). Pigmentation of glandubae on abdominal segment 2 paler than on more anterior parts of dorsum. Pigmentation, size of glandubae on the abdominal dorsum and length of their setae diminish progressively towards the posterior (Fig. 52 ). Subspiracular lobe on abdominal segments 1-3(4) more or less marked with black, extent of black decreasing from segment to segment towards posterior.

Abdomen strongly tapering caudally, ventral surface appearing flat in live specimens. Prolegs very small; developed on abdominal segments 2-6 and 10 (Figs 51 , 52 ), with numerous setae on exterior and interior surfaces; on segments 7-9 a minute scar-like vestige probably homologous with a proleg. Suranal lobe, dorsal and ventral surfaces of subanal lobe extensively black (Fig. 52 ). Posterior surface of anal prolegs dark-marked. Caudal edge of suranal lobe rounded (Fig. 51 ). Subanal lobe projecting beyond suranal lobe (Fig. 52 ). Setae on dorsal surface of subanal lobe particularly long and dense.

Prepupa and pupa.

The trunk of the prepupa (Fig. 58 ) is darker than the larva, the head paler (mostly brown). The pattern of dark thoracic markings is retained. The pupa (Fig. 59 ) is at first pale, darkening progressively as it nears eclosion.

Host plant.

Larvae were found and reared by G. Goergen at the IITAC on Lannea nigritana (Scott-Elliot) Keay ( Anacardiaceae), a small (height 3-6 m), deciduous, heliophilous tree species occurring from Senegal to Gabon, West and Central Africa.

Natural history.

Flight period: June to December, peaking in July and October especially shortly after the annual flushing of individual trees of Lannea nigritana . During peak periods numerous adult sawflies were observed on the host plant. In early October 2014 host trees at the type locality were severely defoliated by Pampsilota dahomeyanus , and large numbers of larvae of all instars were found together with adults. Oviposition is generally on older leaves, with 1-3 eggs laid singly in slits cut into the leaf-blade, next to the midrib, at the base of a leaflet (Fig. 56 ). The female sits on the upperside of the leaf during oviposition. Larvae are gregarious (Fig. 53 ): a group of larvae occupies a whole compound leaf and feeds on plant tissues of all ages. As they mature, larvae turn from dull green to pale yellow. In the laboratory, maturation of the 33 larvae reared from field-collected eggs took about 12 days. When fully grown, the larvae drop onto the soil to spin cocoons. About half of the cohort reared in October 2014 made cocoons, sometimes stuck together, in the leaf litter near the soil surface. Cocoons of the remaining larvae were found at about 5 cm below the soil surface. The cocoon is elongate-oval, about 9 mm long, double-walled, with sand grains attached to the outside (Fig. 57 ). The outer wall is irregularly netted, the inner wall parchment-like separated from the first by a loose layer of silk strands. Whereas eclosion of the individuals which made cocoons above ground occurred already between 20- 27 October 2014, i.e. 7-14 days after making their cocoons, adults emerged from cocoons made in the ground in the period 8-25 June of the following year, i.e. 207-224 days after entering the ground. In both instances, there was no obvious pattern in the emergence of male and female sawflies. It is concluded that Pampsilota dahomeyanus has a multivoltine life cycle with polymodal adult emergence. Parasitism: during larval peak periods imagines of an unidentified Boethus species ( Hymenoptera, Ichneumonidae , Tryphoninae ) were observed attaching eggs externally to the surface of the larvae. Members of the genus are known as koinobiont parasitoids of Argidae larvae. This is the first record of Boethus from West Africa.

Etymology.

The new species name, a Latinised adjective, refers to the historical West African kingdom of Dahomey, the later Republic of Benin, in which the type locality is situated.

Distribution.

Benin (Fig. 36 ).

Diagnosis.

Pampsilota dahomeyanus adults resemble those of Pampsilota nigeriae and Pampsilota tsavoensis in the nearly entirely yellow colour of the abdomen and thorax underside. Pampsilota nigeriae is separated from Pampsilota dahomeyanus by its predominantly light brown to yellow antenna, entirely yellow propleuron, bicoloured stigma, and very different penis valve (Fig. 26 ). Pampsilota tsavoensis differs from Pampsilota dahomeyanus in the blackish dorsal part of its mesepisternum, the shape of the serrulae (Figs 29 , 30 ), and in the shape of the valvulae 3: conspicuously divergent in dorsal view, with distinct denticles on the interior surface (Fig. 28 ), whereas in Pampsilota dahomeyanus the ovipositor sheath is more compact, with the valvulae 3 not diverging distally, and without denticles (Fig. 16 ). The similarly coloured Pampsilota nigeriae , of which only a single male is known, differs from both species in the predominantly yellow antenna and the bicoloured stigma, and from Pampsilota dahomeyanus especially in the shape of the penis valve (Fig. 26 ).

Remarks.

Especially males of Pampsilota dahomeyanus are highly variable in coloration. Four specimens have an entirely black mesonotum, metascutellum, black tegula, blackish markings on the pronotum and tergum 1, and terga (5)6-8 nearly entirely black. However, no accompanying differences in the shape of the penis valve were detected. Sometimes, in both sexes, the clypeus and the supraclypeal area are marked with dirty yellow. In the material studied, one male was found to have a very small subapical spine on one metatibia. We interpret this as a rare reversion to what may be the plesiomorphic character state.

General morphology of the larva is very similar to the Arginae species described by Lorenz and Kraus (1957; in that work represented only by larvae of Arge ), and Smith (1989). Compared to Sterictiphorinae , Pampsilota dahomeyanus larvae share characters of Arge : thoracic leg with six articles (at most 5 in Sterictiphorinae ), abdominal postspiracular lobes without raised or subcutaneous glands (present in Sterictiphorinae ), subanal lobe without pseudocerci (present in Sterictiphorinae ). There is no detailed published description of an Afrotropical argid larva with which to compare Pampsilota dahomeyanus .

Figures

Figure 26. Pampsilota nigeriae: Penis valve (left, lateral aspect).

Figure 36. Distribution map for Pampsilota afer, Pampsilota africanus, Pampsilota brandbergensis, and Pampsilota dahomeyanus.

Figures 15 - 19. Pampsilota dahomeyanus: 15. Valvulae 3 (lateral aspect); 16. Valvulae 3 (dorsal aspect); 17. Lancet; 18. Serrulae 10 - 11; 19. Penis valve (left, lateral aspect).

Figures 45 - 50. Pampsilota brandbergensis ♂ (PT), dorsal / lateral. 47 - 50. Pampsilota dahomeyanus. 47 - 48. ♀, dorsal / lateral; 49 - 50. ♂, dorsal / lateral. Scale bars = 1 mm.

Figures 51 - 59. Pampsilota dahomeyanus, immature stages: 51. Mature larva, from L to R dorsal, lateral, ventral; 52. Young larva, lateral (preserved in ethanol); 53. Larvae on Lannea nigritana; 54. Metathoracic leg; 55. Head, frontal; 56. Eggs in base of leaflet. 57. Cocoons, from L to R with covering of sand, outer layer, inner layer; 58. Prepupa, from L to R ventral, lateral, dorsal; 59. Pupa, from L to R ventral, lateral, dorsal.

Figures 27 - 30. Pampsilota tsavoensis: 27. Valvulae 3 (lateral aspect); 28. Valvulae 3 (dorsal aspect); 29. Lancet; 30. Serrulae 10 - 11.