Marpissoida: Marpissinae

Metacyrba is one of five Marpissine genera in North America. Marpissa with 11 North American species, 3 Neotropical species, and 15 Palaearctic species is the most diverse genus in the group. Metacyrba comprises 6 (plus 1 subspecies) New World species with 3 (plus 1 subspecies) occurring in North America. These spiders range in size from 3-7 mm. They are overall dark and have a somewhat flattened carapace with a thin line of white scaling along the lateral margins. Abdominal marking are typically yellowish to white. Three species/subspecies have a pair of thin, more or less parallel, linear dorsal markings often broken along their length (as the spiders age some or all of these scales may be rubbed off). One species, M. punctata, lacks these linear markings but shows three pairs of characteristic marks on the distal portion of the abdomen. A small dot-like mark of white scaling is often apparent at the tip of the abdomen. Leg I has a noticeably heavy femur and tibia. Leg and or leg segment color differences are keys to species identification and range from black to pale yellowish to bright reddish-orange. These spiders often remain out of sight behind bark or under leaf litter or rocks but are also found foraging along the vertical surfaces of wooden posts, walls, and tree trunks. Although such designations are uncommon among spiders the subspecies Metacyrba taeniola taeniola and Metacyrba taeniola similis display no significant genitalic differences, but occur in different regions of the country, occupy different habitats, and show marked differences in leg coloring. See details below. Edwards (2006) describes a number of somatic variations of these spiders across their ranges including a possible hybrid between the two subspecies. Below is a Metacyrba from Uvalde Co., Texas (6 May 2015) that is possibly a hybrid.
Edwards, 2006