Palpus


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palpus

[′pal·pəs]
(invertebrate zoology)
A process on a mouthpart of an arthropod that has a tactile or gustatory function.
Any similar process on other invertebrates.

Palpus

 

a segmented appendage of the jaws (mandibles and first and second maxillae) in crustaceans, myriapods, and insects, equipped with various sense organs (tactile organs and chemore-ceptors). The palpi are well developed and completely represented in crustaceans; in myriapods and insects there are no palpi on the mandibles. In many insects, especially those with a sucking-type mouth apparatus, the palpi are reduced.

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Colour: Head orange, except for black palpus and swollen part of frontal vitta; notum and upper pleuron brick-red; foreleg black, except tarsus; tarsomeres 1-3 white, distal tarsomeres dark; mid femur black with orange apex, mid femur orange at base and apex; abdomen black, except for extreme base and white fasciae across pleuron on segments 2 and 3 (Fig.
0 times longer than broad, arista pubscent, longest hairs as long as its basal diameter; facial ridge distinctly narrow, lower facial margin projecting, vibrissal angle and frontal angle placed behind lower facial margin in profile; gena covered with dark grey pruinosity, genal height about 1/7-2/9 of eye height; gena with 1-2 rows of upcurved peristomal setae; both postgenal and paragenal setae entirely black; postocular setae extending to ventral surface, the upper lateral area of the occiput with 2 rows of setae; proboscis slender; prementum shiny, sparsely with pruinosity basally, about 6-7 times longer than broad; palpus black, about 4/5 length of prementum.
twice the length of scape and pedicel combined), cylindrical (not widening toward the middle) and with distinct well-developed style; style with numerous, short, tightly packed setae (not longish, loosely arranged setae as in Oligopogon); face narrower than width of one eye in anterior view; facial swelling weak and not well-defined dorsally; mystax occupying about half of facial profile; occiput with macrosetae; palpus 2-segmented; proboscis shorter than antenna, straight and without spine-like processes distally.
used to clasp legs or palps, though the clasped appendages vary: in Euagrus the male clasps the female's femur II (Coyle 1986) and in Porrhothele he clasps the female's palpus (Jackson & Pollard 1990).
Diagnosis: Asilidae with the following combination of characters: Antennal stylus asetose and composed of three elements (2 segment-like elements tipped with a seta-like sensory element); face plane or slightly convex; dorsal postocular macrosetae long, markedly proclinate; palpus 1-segmented; postmetacoxal area membranous; anepisternum lacking strong macroseta at superoposterior angle; anatergites asetose; katatergite with vertical row of macrosetae; prothoracic tibiae without apical spur; metacoxa with at least one lateral macroseta; [R.
2008), as follows: eyes arranged in two rows, presence of a tibial apophysis and a ventrodistal refolded rim on male palpal tibia; male palpus with a large median apophysis with a dorsal embolic groove extending into the guide; female epigynum generally heavily sclerotized, dark and opaque, the epigynal plate is conspicuous and the anterior field wide and usually distinct from the lateral lobes and the female builds a discoid and flattened egg sac, fixed and carried on the spinnerets (Carico 1993).
Head brown, vertex white; antenna yellowish brown except dark brown at base, serrate; labial palpus blackish brown, long and stretch forwardly; proboscis strongly developed.