Sympotthastia update 43 



obliquely arrayed, dark lateral teeth. Ventromental plate (VmP) present, 

 teardrop-shaped, or absent. Antennal AR 1.5 or 2.0-2.5; A 2 appearing 

 very bifid with the blade base fused to it laterally, or appearing normal 

 with the blade base fused to A nearer to the apex of A f ; ring organ in 

 basal fourth; blade and style elongate, reaching at least to A 4 ; A annu- 

 late. Labrum with simple S-setae, mostly simple chaetae, and simple 

 spinulae over premandible. SIII hairlike and SIV lanceolate. Labral 

 lamellae (LL) two broad, simple or slightly denticulate plates. Chaeta 

 media broad at base and sometimes frayed apically. Epipharyngeal area 

 with a three scaled pecten flanked on each side by a pair of larger blades 

 and several thinner spines. Premandible mitten-shaped with 1-4 incon- 

 spicuous lateral teeth on its medial, curved margin; brush spike-like lat- 

 eral spine only. Mandible normal or sickle-shaped as in Potthastia spp. 

 Prementum with three groups of long, flat bristles. Maxilla with a low 

 palp and sensilla; galea without a row of lanceolate pegs. Body moder- 

 ate in length (6-12 mm) and without conspicuous lateral setae even on 

 the 10th segment (base of parapod). Procercus button-like, heavily 

 sclerotized anally, height to width about one, and supporting seven long 

 (about 400 um) anal setae (AS) and two small, unequal lateral setae. 

 Supraanals not reduced, but shorter than anal setae. Anal tubules (TA) 

 fingerlike, rounded or pointed apically, and shorter than parapod. Pos- 

 terior parapod moderately elongate with 16 dark claws. 



Remarks. — The adult males of Sympotthastia, according to Serra- 

 Tosio (1971), is relatively plesiomorphic to Potthastia based on the 

 trends of unreduced chaetotaxy and the cylindrical ta 4 . Using the reduc- 

 tion in chaetotaxy within the genus, a phylogenetic scheme is proposed 

 that includes the Nearctic species and that leaves S. zavreli the most 

 apomorphic (Fig. 14). 



Sympotthastia is a very uniform genus in all stages, but two species 

 groups may be separated. The zavreli-group is mostly Palaearctic, and 

 the /w/va-group is Nearctic. Adults have differences in the palpal 2nd 

 segment, color of capitellum of haltere, and anal point. Pupae show 

 only slight variations in chaetotaxy, and larvae have or do not have 

 ventromental plates and have differently shaped mandibular armature. 

 Specifics are used in the following keys. Because of this homogeneity no 

 subgeneral are proposed. 



Ecology. — The temperate Sympotthastia species can be found in 

 the peneplaned or filled valleys of the foothills-piedmont within the alti- 

 tude of 60 to 220 m. The small streams of these lowland valleys origi- 

 nate in forested hills of about 350 m altitude, and they are secondarily 

 cutting into the floodplain, exposing rock and sand substrate. They are 

 moderately mineralized and relatively free of silt (and pollution). Sur- 

 rounding land is used for moderate agriculture, or remains forested. 



