arolium

arolium

[ə′rōl·ē·əm]
(invertebrate zoology)
A pad projecting between the tarsal claws of some insects and arachnids.
References in periodicals archive ?
Generally speaking, each of the first 4 tarsomeres may bear on its ventral surface a single, colorless pad-like enlargement called the tarsal pulvillus, and there is a soft adhesive lobe called the arolium at the apex of the fifth tarsomere.
In his book The Semiaquatic Bugs, Andersen (1982) established the phylogeny of Gerromorpha, and diagnosed the clade on presence of three pairs of cephalic trichobothria inserted in deep cuticular pits; quadrangular mandibular levers; pretarsi with one dorsal and one ventral arolium, and the female genital tract with a gynatrial complex, including a long tubular spermatheca and a secondary fecundation canal.
Insects' foot pad which includes arolium, palmula and euplantula is an important organ for them to adhere to the slippery surface (CHEN, 2007).
Legs: legs I and II with an oblique junction between femur and patella; legs III and IV without tactile setae on tibiae or tarsi; metatarsus and tarsus fused into single segment (tarsus); tarsi with single raised slit sensillum; subterminal tarsal seta curved and acuminate; tarsal claws simple; arolium slightly shorter than claws.
1), tarsus three-segmented on all pairs of legs; pretarsus of foreleg with large, membranous ventral arolium, and a slightly sclerotized lobe in dorsal position that may represent the dorsal arolium (Fig.
Pseudalbiorix can be further separated from the other recognized genera of Ideoroncidae as follows: from the American genus Albiorix by the lack of a divided arolium; from the American genus Ideoroncus by the presence of 4 setae on the anterior margin of the carapace (6 setae in Ideoroncus) and the position of trichobothrium st which is situated slightly ventral to the level of sb in Ideoroncus but is not ventrally displaced in Pseudalbiorix (or any other ideoroncid); from the American genus Typhloroncus by the long arolium, the presence of eyes and by the slightly lower number of trichobothria (30 in Pseudalbiorix and 32 or 33 in Typhloroncus); from the Asian genera Dhanus, Shravana and Nhatrangia and the African genus Negroroncus by the absence of a lamina exterior [except in D.
Female of Dryinus without notauli and with enlarged claw not reduced, much longer than arolium, with one only subapical tooth and one row of lamellae, without a broad apical lamella.
As in the other Neotermes species examined, legs with 3 tibial spurs, arranged 3:3:3; arolium present.
The new genus bears a peculiar structure on the arolium that is only found in a few other genera of Ideoroncidae.
SEM of the ACP tarsus showed prominent tarsal claws and a large, pad-like arolium between the claws (Fig.