Genus of spiders
Hemirrhagus is a genus of Mexican tarantulas that was first described by Eugène Louis Simon in 1903. It is considered a senior synonym of "Spelopelma". Species of the genus "Hemirrhagus" are 5 to 12 cm long, usually black in colour, the urticating hairs on the opisthosoma are arranged in one dorsomedian patch, two dorsal paramedian patches, or two lateral patches. It is unique amongst the theraphosine genera because of the retrolateral coxal heels, the shape of the male palpal bulb, and the urticating hairs on the abdomen are reduced or completely missing. It is the only genus with epigean, troglophile and troglobitic species.
Distribution.
Hemirrhagus tarantulas are all found in Mexico all of them are largely distributed from Tamaulipas in the north to Chiapas in the south, primarily in the mountainous regions of Sierra Madre Oriental, Eje Volcánico Transversal, Sierra Norte de Oaxaca, and Sierra Madre Sur. All of this tarantulas are found in individual caves, some species living in the same cave. The species are found in cave systems between 100m to 1900m above sea level. Most of them are found in central Mexico and the northern part of south Mexico. 
References.
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