Megastigmus seed chalcids (Hymenoptera, Torymidae) radiated much more on Angiosperms than previously considered. I- Description of 8 new species from Kenya, with a key to the females of Eastern and Southern Africa

Abstract

A survey of seed chalcids from woody plants in Kenya revealed 12 species belonging to the genus Megastigmus Dalman, 1820, and has increased to 16 the number of Megastigmus species presently recorded from the Afrotropical Region, of which at least 13 are seed feeders. A key to female Megastigmus of the Afrotropical Region is provided. Eight new species are described from morphological evidence: Megastigmus lanneae Roques & Copeland, Megastigmus laventhali Roques & Copeland, Megastigmus ozoroae Roques & Copeland, and Megastigmus smithi Roques & Copeland in seeds of species of the family Anacardiaceae, Megastigmus copelandi Roques & Copeland and Megastigmus grewianae Roques & Copeland in seeds of Malvaceae, Megastigmus helinae Roques & Copeland in seeds of Rhamnaceae, and Megastigmus icipeensis Roques & Copeland for which no host is known. These collections include the first records of Malvaceae and Rhamnaceae as hosts of Megastigmus seed chalcids, which appear to have radiated in Angiosperms much more than previously considered. Analyses of the mitochondrial (cytochrome oxidase subunit one - COI) and nuclear DNA (28S ribosomal region) could be carried out on 8 of the 16 African species of which 5 were newly described ones. The species associated with Anacardiaceae always clustered together in phylogenies, confirming the existence of a strong and ancestral monophyletic clade, unlike the ones associated with Malvaceae and Rhamnaceae, whose position remains unclear. All holotypes are deposited in the National Museums of Kenya.

Keywords: Africa; Anacardiaceae; Chalcidoidea; Malvaceae; Megastigmus; Rhamnaceae; fruit; new species; plant hosts; seed.

Figure 1.

Distribution in Kenya of the previously described African Megastigmus species.

Figure 2.

Distribution in Kenya of the new Megastigmus species identified during our study.

Figures 3–9.

Anacardiaceae host fruits of Megastigmus spp. in Kenya. 3 Lannea cf. schimperi 4 Lannea rivae 5 Lannea schweinfurthii 6 Ozoroa insignis subsp. reticulata 7 Ozoroa obovata 8 Pistacia lentiscus subsp. emarginata 9 Rhus natalensis (note the chalcid hole in a fruit).

Figures 10–13.

Other host fruits of Megastigmus spp. in Kenya. 10 Helinus integrifolius (Rhamnaceae) 11 Grewia tephrodermis (Malvaceae) 12 Grewia stuhlmannii 13 Juniperus procera (Cupressaceae).

Figure 14.

Bayesian-likelihood inference phylogenies based on cytochrome oxidase I (COI) and ribosomal DNA (28S) sequences in seed-specialized wasps of the Megastigmus genus. A Short fragment COI (34 taxa, 417bp) B Long fragment COI (31 taxa, 810pb) C Nuclear fragment (33 taxa, 924pb). Torymus azureus Boheman, 1834 was used as an outgroup. Posterior probability values are indicated at each node. New taxa described in this paper are indicated in red and bold. Branches of taxa associated with Anacardiaceae as host plant family are in blue, and branches of taxa associated with Cupressaceae are in green.

Figures 15–21.

Megastigmus helinae Roques & Copeland, sp. n. female. 15 dorsal view of the body 16 lateral view of body 17 dorsal view of thorax 18 front view of head 19 electroscan of antenna 20 electroscan of dorsal view of thorax 21 forewing.

Figures 22–29.

Megastigmus helinae Roques & Copeland, sp. n. male. 22 dorsal view of the body 23 lateral view of body 24 dorsal view of thorax 25 front view of head 26 electroscan of antenna 27 electroscan of dorsal view of thorax 28 forewing 29 genitalia.

Figures 30–35.

Megastigmus smithi Roques & Copeland, sp. n. female. 30 dorsal view of the body 31 lateral view of body 32 dorsal view of thorax 33 front view of head 34 antenna 35 forewing.

Figures 36–41.

Megastigmus copelandi Roques & Copeland, sp. n. female. 36 dorsal view of the body 37 lateral view of body 38 dorsal view of thorax; 39 front view of head 40 antenna 41 forewing.

Figures 42–47.

Megastigmus ozoroae Roques & Copeland, sp. n. female. 42 dorsal view of the body 43 lateral view of body 44 dorsal view of thorax 45 front view of head 46 antenna 47 forewing.

Figures 48–54.

Megastigmus ozoroae Roques & Copeland, sp. n. male pale form. 48 dorsal view of the body 49 lateral view of body 50 dorsal view of thorax; 51 front view of head 52 antenna 53 genitalia 54 forewing.

Figures 55–61.

Megastigmus ozoroae Roques & Copeland, sp. n. male dark form. 55 dorsal view of the body 56 lateral view of body 57 dorsal view of thorax; 58 front view of head 59 antenna 60 genitalia 61 forewing.

Figures 62–67.

Megastigmus icipeensis Roques & Copeland, sp. n. female. 62 dorsal view of the body 63 lateral view of body 64 dorsal view of thorax 65 front view of head 66 antenna 67 forewing.

Figures 68–74.

Megastigmus icipeensis Roques & Copeland, sp. n. male. 68 dorsal view of the body 69 lateral view of body 70 dorsal view of thorax 71 front view of head 72 antenna 73 forewing 74 genitalia.

Figures 75–80.

Megastigmus laventhali Roques & Copeland, sp. n. female. 75 dorsal view of the body 76 lateral view of body 77 dorsal view of thorax 78 front view of head 79 antenna 80 forewing.

Figures 81–87.

Megastigmus grewianae Roques & Copeland, sp. n. female. 81 dorsal view of the body 82 lateral view of body 83 dorsal view of thorax 84 electroscan of dorsal view of thorax 85 front view of head 86 electroscan of antenna 87 forewing.

Figures 88–95.

Megastigmus grewianae Roques & Copeland, sp. n. male. 88 dorsal view of the body 89 lateral view of body 90 dorsal view of thorax 91 front view of head 92 electroscan of antenna 93 electroscan of dorsal view of thorax 94 forewing 95 genitalia.

Figures 96–101.

Megastigmus lanneae Roques & Copeland, sp. n. female. 96 dorsal view of the body 97 lateral view of body 98 dorsal view of thorax 99 front view of head 100 antenna 101 forewing.

Figures 102–108.

Megastigmus lanneae Roques & Copeland, sp. n. male pale form. 102 dorsal view of the body 103 lateral view of body 104 dorsal view of thorax 105 front view of head; 106 antenna 107 genitalia 108 forewing.

Figures 109–115.

Megastigmus lanneae Roques & Copeland, sp. n. dark form. 109 dorsal view of the body 110 lateral view of body 111 dorsal view of thorax 112 front view of head; 113 antenna 114 forewing 115 genitalia.

Figures 116–121.

Megastigmus hypogeus Hussey female. 116 dorsal view of the body 117 lateral view of body 118 dorsal view of thorax 119 front view of head 120 antenna 121 forewing.

Figures 122–128.

Megastigmus hypogeus Hussey male pale form. 122 dorsal view of the body 123 lateral view of body 124 dorsal view of thorax 125 front view of head; 126 antenna 127 genitalia 128 forewing.

Figures 129–135.

Megastigmus hypogeus Hussey male dark form. 129 dorsal view of the body 130 lateral view of body 131 dorsal view of thorax 132 front view of head; 133 antenna 134 genitalia 135 forewing.

Figures 136–141.

Megastigmus pistaciae Walker female. 136 dorsal view of the body 137 lateral view of body 138 dorsal view of thorax 139 front view of head 140 antenna 141 forewing.

Figures 142–149.

Megastigmus pistaciae Walker male. 142 dorsal view of the body (pale form) 143 lateral view of body (pale form) 144 dorsal view of thorax(pale form) 145 lateral view of body (dark form) 146 front view of head (pale form); 147 antenna (pale form) 148 genitalia (pale form) 149 forewing (pale form).

Figures 150–155.

Megastigmus transvaalensis Hussey female. 150 dorsal view of the body 151 lateral view of body 152 dorsal view of thorax 153 front view of head 154 antenna 155 forewing.

Figures 156–162.

Megastigmus transvaalensis Hussey male. 156 dorsal view of the body 157 lateral view of body 158 dorsal view of thorax 159 front view of head; 160 antenna 161 forewing 162 genitalia.

Figures 163–167.

Megastigmus somaliensis Hussey. 163 lateral view of female body 164 electroscan of front view of male head 165 electroscan of male antenna 166 electroscan of dorsal view of male thorax 167 male forewing.

Figure 168.

Updated synthesis of biological habits of the world Megastigmus species recorded to date with a detail of the species present in Eastern and Southern Africa. The four bars on the top detail the chalcid feeding regimes. The following ones present the host plant families colonized by the phytophagous seed chalcids, splitted into angiosperms and conifers.