Family: MEROTHRIPIDAE

 

This family includes 17 species in three genera, but 15 of these are placed in the genus Merothrips. Currently, there is no satisfactory way to distinguish this family from the Melanthripidae, species in both families retaining paired lobes on the posterior margin of sternite VII that are considered to represent the sternite VIII of ancestral Thysanoptera.

Species of Merothrips have antennae with only 8 segments, and many species are known only from wingless adults. In contrast, the two species in the other two merothripid genera, including Erotidothrips mirabilis that is illustrated here (see Images), have 9-segmented antennae and have fully winged adults. Merothripidae are widespread in the tropics and sub-tropics, but they are minute and rarely collected. They feed on fungi, and live on dead twigs and in leaf litter (Mound & O'Neill, 1974). They are never pests of crops, but specimens are sometimes taken in traps.


Merothrips floridensis Watson

Available names: Original name Merothrips floridensis Watson, 1927. Synonyms Merothrips capensis Faure, 1938; Merothrips plaumanni Crawford, 1942; Merothrips xylphilus Strassen, 1959; Merothrips priesneri, Bournier, 1960; Merothrips zondagi Ward, 1969.


Biology: Fungus feeding, on dead twigs and in leaf litter. Most individuals are apterous, but winged females are sometimes taken in traps associated with crops.


Distribution: Recorded from N. & S. America, southern France, Azores, southern Africa, Japan, Australia, New Zealand, & Hawaii.


Recognition: Minute, yellow or yellowish brown, usually wingless thrips. Head smaller than the trapezoidal pronotum, eyes small, one pair of long interocular setae. Antennae 8-segmented, almost moniliform, VIII spindle shaped, III & IV with transversely oval sensory area at apex. Pronotum with one pair of long posteroangular setae, dorsal surface with sculpture limited to 2 or 3 transverse lines postero-medially; paired longitudinal sutures anterolaterally. Mesonotum with pair of long lateral setae. Tarsi 2-segmented. Abdomen slender, without long setae except at apex; tergite X with pair of trichobothria at posterior margin; sternite VII posterior margin with pair of large lobes each bearing a pair of setae at base; ovipositor valves very weak, margins not toothed.
Male smaller than female; dorsal surface of head occupied by large glandular area; fore femora sometimes enlarged, fore tibia with tooth at inner apex.


Related species: Between 12 and 15 species are listed in this genus, although recognition of these species, also their generic placement, is disputed by different authors. M. morgani Hood is the second most commonly collected and widely distributed species, and is distinguished from M. floridensis by the presence of numerous faint lines of sculpture medially on the pronotum.


Generic relationships: Only three genera are recognised in the family Merothripidae, the other two each including a single species (Mound & O'Neill 1974). The two most distinctive species within Merothrips have also been referred to two separate genera, but this is not currently accepted (Mound & Marullo 1996).

         

Merothrips floridensis

Merothrips antennae