Systematics of the Madagascar Anelosimus spiders: remarkable local richness and endemism, and dual colonization from the Americas Author Agnarsson, Ingi Author Jencik, Brian B. Author Veve, Giselle M. Author Hanitriniaina, Sahondra Author Agostini, Diego Author Goh, Seok Ping Author Pruitt, Jonathan Author Kuntner, Matjaz text ZooKeys 2015 509 13 52 http://dx.doi.org/10.3897/zookeys.509.8897 journal article http://dx.doi.org/10.3897/zookeys.509.8897 1313-2970-509-13 6DD8D4EB478844E2B34C995D87F2A0DE 6DD8D4EB478844E2B34C995D87F2A0DE Taxon classification Animalia Araneae Theridiidae Anelosimus lamarcki Agnarsson & Goh sp. n. Fig. 9 Type material. Holotype female from Ranamofana National Park ( 21.25°S , 47.43°E ), montane rainforest, 9801050 m alt, 27.iv.-2.v.2013, col. Pruitt, in NMNH. Other material. Same locality and collection, several adult females. Etymology . The species epithet is a noun in genitive case that honors the early evolutionary biologist Jean-Babtiste Lamarck, the first scientists to develop a thorough and coherent evolutionary theory, though it was later shown by Darwin to be flawed in major ways. Diagnosis. Anelosimus lamarcki can be diagnosed from other Madagascan Anelosimus by the heavily sclerotized copulatory ducts and small spermathecae that barely exceed the diameter of the copulatory ducts. Anelosimus lamarcki can be diagnosed from other Madagascan Anelosimus on the basis of the following unique mtDNA nucleotide substitutions at the following standard DNA barcode alignment positions: G (280), C (562). It can also be readily diagnosed from most other Anelosimus based the following partially shared nucleotide substitutions, and all other species by their unique combination: G (502, except rarely in Anelosimus may ), G (514, except Anelosimus hookeri and most Anelosimus vondrona ), G (553, except some Anelosimus huxleyi ), G (766, except some Anelosimus may ), G (772, except Anelosimus andasibe ), G (814, except most Anelosimus vondrona ). Figure 9. Anelosimus lamarcki : A-B female dorsal and lateral views C epigynum ventral view D epigynum cleared dorsal. Description. Female (holotype): Total length 5.16. Cephalothorax 2.32 long, 1.70 wide, 0.98 high, dark brown. Abdomen 2.88 long, 2.04 wide, 1.90 high. Light brown base with black/white spots, black and white longitudinal band extending just beyond half of abdomen, red marks near spinnerets. Eyes subequal in size about 0.14 in diameter. Leg I femur 2.77, patella 0.84, tibia 2.34, metatarsus 2.28, tarsus 0.91. Leg formula 1423. Leg light orange-brown, with alternating light and dark shaded bands, and very dark at distal tips of femur, patella, tibia and metatarsus. Numerous (6 - 7) small trichobothria dorsally on all tibia, 7 on tibia I, 6 on tibia II, 7 on tibia III, 6 on tibia IV. Variation : Total length 5.00-6.80. Prosoma 2.30-2.90 long. Abdomen 2.70-3.20 long. Femur I 2.70-3.20. Distribution. Only known from type locality. Natural history. We sampled twelve colonies of Anelosimus lamarcki . Colonies were found both along trails in the forest interior and along roadsides and ornamental shrubbery. The ten colonies in the forest interior contained females with groups of small juveniles, likely instars I-II , and colonies along road sides contained one penultimate or mature female. Like Anelosimus vondrona , Anelosimus lamarcki webs contained an impressive diversity of foreign spiders including multiple theridiids, saliticids, sparassids, a thomisid, and several linyphiids. We observed multiple co-feedings events between Anelosimus lamarcki and its web associates during staged prey capture events. Whether Anelosimus lamarcki or its web associate was the first to subdue the prey differed across trials.