''Chaco tucumana'' is a species of
mygalomorph
The Mygalomorphae, or mygalomorphs, are an infraorder of spiders, and comprise one of three major groups of living spiders with over 3000 species, found on all continents except Antarctica. Many members are known as trapdoor spiders due to t ...
spiders of
Argentina
Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...
, named after its type locality:
Tucumán.
[Goloboff, Pablo A. "A revision of the South American spiders of the family Nemesiidae (Araneae, Mygalomorphae). Part 1, Species from Peru, Chile, Argentina, and Uruguay. Bulletin of the AMNH; no. 224." (1995).] This species differs from ''
C. obscura'' in the shorter male embolus and the shorter female
spermatheca
The spermatheca (pronounced plural: spermathecae ), also called receptaculum seminis (plural: receptacula seminis), is an organ of the female reproductive tract in insects, e.g. ants, bees, some molluscs, oligochaeta worms and certain other in ...
l ducts. From other species of the genus it differs in its dark uniform color, the flexible anterior female
tarsi, the denser
scopulae
Scopulae, or scopula pads, are dense tufts of hair at the end of a spiders's legs. They are found mostly on hunting spiders, especially Lycosidae and Salticidae. Scopulae consist of microscopic hairs, known as setae, which are each covered in even ...
on the posterior tarsi, and the female spermathecae without a basal protuberance. As in ''C. obscura'', smaller specimens are much lighter in color, and it has darker spots that are evident on the sides of its cephalic region, the apex of femora, base of the patellae and lateral tibiae and dorsal abdomen. Larger specimens are much darker, almost black, with no visible pattern.
Description
The male has a total length of ; a
cephalothorax length of and width of ; a cephalic region length of and width of ; a medial ocular quadrangle (OQ) length of and width of ; a labium length of and width of ; and a
sternum
The sternum or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major blood vessels from injury. Sha ...
length of and width of . The labium possesses one cuspule. A serrula is present. The sternal sigilla is medium-sized, oval, and submarginal.
Chelicerae
The chelicerae () are the mouthparts of the subphylum Chelicerata, an arthropod group that includes arachnids, horseshoe crabs, and sea spiders. Commonly referred to as " jaws", chelicerae may be shaped as either articulated fangs, or similarl ...
: the rastellum is as in the female; the inner margin has seven teeth. The cheliceral
tumescence
Tumescence is the quality or state of being tumescent or swollen. Tumescence usually refers to the normal engorgement with blood (vascular congestion) of the erectile tissues, marking sexual excitation, and possible readiness for sexual activity ...
is flat, covered with thin
setae
In biology, setae (singular seta ; from the Latin word for " bristle") are any of a number of different bristle- or hair-like structures on living organisms.
Animal setae
Protostomes
Annelid setae are stiff bristles present on the body. ...
on its inferior half. The cephalothorax, legs, and
palpi
Pedipalps (commonly shortened to palps or palpi) are the second pair of appendages of chelicerates – a group of arthropods including spiders, scorpions, horseshoe crabs, and sea spiders. The pedipalps are lateral to the chelicerae ("jaws") and ...
are blackish-brown; the abdomen is brown with light-brown spots.
The female has a total length of ; a cephalothorax length of and width of ; a cephalic region length of and width of ; fovea width ; an OQ length and width of ; a labium length of and width of ; and a sternum length of and width of . Its cephalic region is convex, while the fovea is slightly procurved, almost straight. The labium has two cuspules. A serrula is absent. The sternal sigilla is small, submarginal, and of medium depth; the sternum is rebordered. The rastellum is as in ''
C. obscura''. The colour is the same as in the male.
Distribution and behaviour
The animals construct burrows with a door, or sometimes two. The door normally is about in diameter. The burrow has smooth, well-cemented and compacted walls, with a thin (soil-colored) layer of compact silk; it is only to , with a diameter of about .
Most of the specimens were collected at the foot of almost vertical banks or the foot of large trees in
Tucuman and
Catamarca. Juveniles found elsewhere might extend this apparent habitat distribution.
See also
*
Spider anatomy
The anatomy of spiders includes many characteristics shared with other arachnids. These characteristics include bodies divided into two tagmata (sections or segments), eight jointed legs, no wings or antennae, the presence of chelicerae and pe ...
*
List of Nemesiidae species
References
Further reading
*Study on a Mygalomorph spider community in central Argentina:
External links
ADW entry
{{Taxonbar, from=Q654809
Nemesiidae
Spiders of Argentina
Spiders described in 1995