Franklinothrips Back

Mound, Laurence A. & Reynaud, Philippe, 2005, Franklinothrips; a pantropical Thysanoptera genus of ant­mimicking obligate predators (Aeolothripidae), Zootaxa 864, pp. 1-16 : 4-5

Franklinothrips Back

Franklinothrips Back, 1912: 75 . Type species Aeolothrips vespiformis Crawford Mitothrips Trybom, 1912: 146 . Type species Mitothrips megalops Trybom

Spathiothrips Richter, 1928: 32 . Type species S. bischoffi Richter (= F. megalops )

Generic diagnosis: Macropterous, sexually dimorphic, dark­bodied species. Female with abdominal segments I & II more or less constricted and sometimes sharply pale, thus producing an ant­like body outline. Antennal segments III–IV exceptionally long and slender, III at least 8 times as long as wide and with elongate and sinuous or multifacetted sensoria. Head without long setae, usually partially retracted into prothorax and slightly prolonged in front of eyes; fore ocellus small, about half diameter of hind ocelli; compound eyes prolonged ventrally with enlarged posterior ommatidia; maxillary palps 3­segmented, segment III short. Pronotum with no long setae, posterior margin with stout transverse apodeme. Mesonotum usually with no sculpture on anterior half, with one pair of dominant setae medially. Metanotum without sculpture medially, with one pair of setae at anterior and one pair posteromedially. Forewings slender, costal margin with cilia but no setae; clavus usually with 5 (range 4–7) marginal setae. Fore tarsus with strongly recurved ventral hamus. Abdominal segment I constricted; tergites III–VI with median setal pair small and wide apart; sternites with two pairs of setae close to posterior margin and one or two pairs of discal setae laterally (these probably represent migrated posteromarginal setae); sternite VII with two pairs of accessory setae submedially; paired trichobothria on tergite X small. Male smaller than female, abdomen slender, wings usually paler, tergite I with pair of longitudinal ridges terminating in square or rounded apex overhanging tergite II.

Comments: The species in this genus are particularly uniform in the details of their body sculpture and chaetotaxy. The differences between species are related primarily to the degree of ant­mimicry exhibited (see habitus photographs Figs 3–17 ), including the colour of the forewings, abdomen, and basal antennal segments, the extent to which the first abdominal segment is constricted, and the extent to which the head is recessed into the prothorax. This latter character state is particularly difficult to assess, because although in the living insect the head may be withdrawn into the prothorax, the process of slidemounting commonly changes the orientation of the head to the pronotum, as mentioned below under F. variegatus (cf. original illustration of F. suzukii Okajima and Fig. 19 ). Stannard (1952) provided an extensive account of the genus, with a key to the six species then known. Mound & Marullo (1996) provided a brief diagnosis and key to the six Neotropical species, although the character state involving the colour of antennal segment IV that is used, in part, to distinguish F. orizabensis from F. vespiformis is clearly incorrect. Since 1996, three further species have become available, F. basseti from Australia and two new species described below.

Generic relationships: The monobasic genus Corynothripoides Bagnall from Africa is the only genus that is closely related to Franklinothrips , differing in the greater pre­ocular prolongation of the head, but with the metanotum and the chaetotaxy of the abdominal sternites essentially similar. The only known species, C. marginipennis Bagnall , has the head strongly prolonged in front of the eyes, and the first ocellus either absent or reduced even more than in Franklinothrips brunneicornis ( Figs 18, 20 ). The forewing longitudinal veins are widely separated, each unusually close to a wing margin, but this is also true of F. lineatus ( Fig. 6 ). Should further material become available for study, Corynothripoides might need to be considered as a synonym of Franklinothrips . Antennal segments III and IV are yellow in C. marginipennis , with sensoria essentially similar to those of Franklinothrips species, and the forewing has the anterior and posterior margins dark with a median longitudinal pale area much as in F. lineatus ( Fig. 6 ). The holotype female (in BMNH) was collected in Sierra Leone. The only other known specimens [in SMF] are two females from Rwanda and one female from Zaire. One male from Uganda with antennal segment III dark not yellow is probably this species, because similar sexual dimorphism is known in Franklinothrips . Nothing is known of the biology of C. marginipennis , although it is likely to be a predator of other thrips on the leaves of forest trees.

Figures

FIGURES 1 – 11. Franklinothrips species: (1) F. vespiformis female; (2) F. vespiformis larva; (3) F. a tla s, female holotype; (4) F. basseti, female holotype; (5) F. brunneicornis, female holotype; (6) F. lineatus, topotypic female; (7) F. lineatus, topotypic male; (8) F. fulgidus, female holotype; (9) F. m e g a l o p s, female from India; (10) F. o r i z a b e n s i s, female from California; (11) F. o r i z a b e n s i s, male from California.

FIGURES 12 – 20. Franklinothrips species: (12) F. strasseni, female holotype; (13) F. tenuicornis, female from Sta Catarina, Brazil; (14) F. tenuicornis, male from Sta Catarina, Brazil; (15) F. variegatus, female; (16) F. vespiformis, female from Sao Paulo, Brazil; (17) F. vespiformis, male from Sedona, Arizona, USA; (18) F. brunneicornis, female head; (19) F. s u z u k i i, female holotype; (20) F. brunneicornis, male head.