Malthonica ferruginea is a typical median to large sized agelenid spider, living in funnel-webs which are attached to rock faces, tree trunks or buildings. Due to the dark reddish band present on the back of the spider’s opisthosoma, this species can easily be recognized in Central Europe. In Southern Europe, this character is not diagnostic since other species have a comparable reddish band on their opisthosoma, too.

Measurements: Male (n=1): Carapace 6.40 long, 5.00 wide; labium as long as wide; sternum 3.00 long, 2.85 wide; opisthosoma 7.35 long, 5.03 wide. Ratio bulb length (laterally from cymbium base to conductor tip) to cymbium length: 0.8. Leg measurements: pedipalp (3.20, 1.00, 1.35, 3.27), leg I (7.85, 2.60, 6.95, 8.00, 3.60), leg II (7.35, 2.55, 6.05, 7.10, 3.25), leg III (6.50, 2.25, 5.25, 6.50, 2.55), leg IV (7.90, 2.45, 6.70, 8.55, 3.20). Female (n=1): Carapace 6.12 long, 4.90 wide; ; labium as long as wide; sternum 3.45 long, 2.88 wide; opisthosoma 8.25 long, 5.93 wide. Epigynal plate 1.00 long, 1.52 wide; atrium 0.37 long, 0.74 wide. Leg measurements: pedipalp (2.69, 1.04, 1.54, 2.96), leg I (7.01, 2.40, 6.08, 7.13, 3.34), leg II (6.60, 2.40, 5.40, 6.38, 2.78), leg III (5.94, 2.10, 4.32, 6.00, 2.50), leg IV (7.30, 2.35, 6.12, 7.90, 3.03).
Eyes: In dorsal view AER straight, PER procurved; frontal view AER slightly procurved, PER strongly procurved. Diameters: PME: 0.2. PLE: 0.25. AME: 0.26. ALE: 0.26. Distances: PME-PME less than 1.5 diameters of PME; PME-AME less than 1.5 diameters of PME; PME-PLE less than 1.5 diameters of PME; PME-ALE less than 2 diameters of PME; AME-AME less than half diameter of AME; AME-ALE less than half diameter of AME. Clypeus hight (measured under AME) less than 2 diameters of AME, (measured under ALE) less than 2 diameters of ALE.
Colouration: Carapace with broad dark margin, discontinuous, with 3–5 crescent-shaped spots; two longitudinal symmetric darkened bands present on carapace; serrated. Chelicerae with a pattern of dark spots. Sternum with distinct pattern of pale median band, interrupted at approximatly 3/4 of sternum length, and 3 symmetric dots at the sides. Opisthosoma dark pigmented with red-brownish median band, anterior besides this band two pale bands, continuing to posterior in dots. Legs annulated.
Additional somatic characters: Distal margin of labium straight. Plumouse hairs present at carapace, legs and opisthosoma. Pro- and retromargin of chelicerae with 4 teeth. Tarsi with 6–8 dorsal trichobothria; trichobothria on male and female palp tarsi present. Colulus forming distinct trapezoidal plate, only partly colored. PLS longer than all others with distal segment shorter than basal segment. Basal segment darkened, distal segment pale. ALS weakly darkened.
Male palp: RTA with dorsal branch strongly sclerotised horn-like, pointed; lateral branch lobe like, strongly sclerotised; ventral branch forming long drawn-out bulge. Embolus filiform, originating (free apex) between 6 and 8 o'clock, free apex longer than 2.5 cymbium width with distal tip between 4 o'clock position, conspicuously formed. Conductor with distal portion strongly elongated and curved, lateral margin completely folded. Terminal end bifid, ventral part short, simple and truncated with a very small point, dorsal part plate like, shorter than ventral part. Connection between conductor and tegulum moderately sclerotised. MA strongly protruding with hook like distal sclerite, membranoulsy connected to tegulum and originating at 6 o'clock. Basal part of tegulum good visible and with undulated margin.
Epigynum and vulva: Epigyne medially with a small pale, membranous area. Posterior sclerite expressed as an extensive sclerotised bar with anterior margin concave (semi-circled) and medially moderately protruding. CO between and laterally of the membranous median area and the posterior sclerit. Epigynal „pseudo teeth“ absent. Vulva consists of combined ducts (CBD), no distinct RC recognisable. Only very first part (CD) of CBD moderately sclerotised, largest part strongly sclerotised and convoluted, forming connected smaller anterior and a larger posterior spiral regions. Ducts are separated by less than their duct diameters. FD only represented by small leave shaped appendages distally of the CBD.

Sequences are available online at: http://www.ncbi.nlm.nih.gov/sites/entrez?db=nucleotide&cmd=Search&dopt=DocSum&term=txid680310[Organism%3Anoexp]

Malthonica ferruginea is closest related to Tegenaria parietina. Females can be separated from T. parietina by the lateral margins of the median region of the epigyne following distinctly the run of the posterior sclerit (especially anteriorly, in T. parietina this margin runs towards the middle of the epigyne), the differently shaped posterior sclerit and the vulva much stronger convoluted (especially the first spiral) and less separated (less than 2 duct diameters, more than 3 in T. parietina). Other characters are presented in detail by Oxford & Merrett (2000). Males of M. ferruginea do have a relatively short cymbium (much longer, in relation to the bulb, in T. parietina), a distinctly longer and curved distal portion of the conductor (short and almost straight in T. parietina) and a differently shaped ventral portion of the terminal end of the conductor.

Records are known from most European countries. Probably absent from northeast Europe.
A specimen from Venezuela would be the first record outside of the Palaearctic region. If the label is correct, M. ferruginea, or at least one specimen of this species, has been introduced in South America.

The most comprehensive phylogenetic study (based on morphological and molecular data) of the European agelenids to date (Bolzern et al., in preparation) places M. ferruginea back to the genus Tegenaria. M. ferruginea is the sister species of T. parietina. This result is supported by the results presented by Bolzern et al. (2010).