Glebych minutissimus, Eskov & Marusik, 2021

Eskov, Kirill Y. & Marusik, Yuri M., 2021, Glebych minutissimus gen. et sp. nov., the smallest cobweb spider (Araneae Theridiidae), Zootaxa 5006 (1), pp. 45-53 : 47-51

Glebych minutissimus sp. n.

Figs 1–5

Types. Holotype ♂ ( ZMMU) and paratypes 9♂ 20♀ (shared between ZMMU and MMUM) PERU, Junin Region, Calabaza Village , 11º30′33′′S 74º50′35′′W, 2500 m, foggy forest, in epiphytic mosses and bromeliads, 19– 20.09.2017 (K.Y. Eskov).

Etymology. The species name, minutissimus , refers to the minute size of the species (smallest among all known Theridiidae ).

Description. Total length ♂ 0.786–8.57, ♀ 0.84–0.91.

Male. Measurements: total length 0.79; carapace 0.36 long, 0.37 wide, 0.23 high; sternum 0.23 long, 0.26 wide; clypeus 0.13 high. Abdomen 0.6 long (longest axis), 0.5 wide, 0.44 high. Chelicera 0.18 long. Palp: 0.59 (0.24 (ø 0.05), 0.1, 0.07, 0.18). Legs: I 1.23 (0.39, 0.16, 0.26, 0.21, 0.21); III 0.81 (0.27, 0.12, 0.13, 0.12, 0.17); IV 1.01 (0.3, 0.11, 0.23, 0.16, 0.21). AME 0.06, AME–AME 0.04. Ocular region with 3 setae anteriorly and 4 setae dorsally. Chelicerae with set of 3 promarginal teeth located on kind of ridge, teeth subequal in length. Sternum strongly bulged ( Fig. 1B, E ). Abdomen uniformly coloured, evenly covered with setae. Epiandrus slightly bulged, darken, some structure visible through integument ( Fig. 1B–C ).

Palp as in Figs 1A–D , 2A–B, I , 3 ). Femur long and thin, ca. 5 times longer than wide; patella elongate, longer than tibia; tibia with 1 trichobothrium; cymbium square shaped, anterior part not modified, cymbial spur (Cs) sharply pointed, with 1 strong seta (Ss) on the base, seta longer than spur; tegulum with retrolateral pit (Tp); embolic division (=radix) hidden under median apophysis (Ma); median apophysis with large square shaped part having serrate retrolateral margin (Sm) and anterior process (Mp); conductor (Co) large.

Female. Measurements: total length 0.91; carapace 0.39 long, 0.4 wide, 0.27 high; sternum 0.24, 0.28 wide; abdomen 0.76 long (longest axis), 0.58 wide, 0.48 high. Palp 0.42 (0.16, 0.08, 0.07, 0.11). Legs: I 1.15 (0.4, 0.14, 0.2, 0.19, 0.2), tarsal organ I 0.7; II 0.86 (0.3, 0.14, 0.15, 0.12, 0.15), IV 0.89 (0.33, 0.12, 0.18, 0.11. 01.5).

Chelicerae with set of 5 promarginal teeth located on a kind of ridge, mesal tooth (Mt) much smaller than other. Palp with claw subequal to diameter of tarsus.

Epigyne as in Figs 1F , 2J–K , 4H–L ; epigynal plate (Ep) ca. 1.7 times wider than long, with lighter median part, formed by median plate (Me); plate and surroundings with long macrosetae, some as long as median plate’s height; copulatory openings heavily sclerotized, their distance as longs as median plate’s height; furrow between epigynal and median plates leading to copulatory openings (Oc); receptacles droplet-shaped, as long as median plate’s height, anterior parts spaced by less than one diameter.

Note. Postgastral area of the female illustrated ( Figs 4I–J ) has 2 fine pits that are most probably artefacts. Such pits are not visible in SEM images ( Fig. 4K–L ).

Figures

FIGURE 1. General appearance of Glebych minutissumus sp. n. of the male (A–D) and female (E–F). A prosoma, dorsal; B, E body, lateral; C, F body, ventral; D prosoma, dorso-lateral. Scale = 0.2 mm. Abbreviation: Ts tracheal spiracle.

FIGURE 2. SEM images of Glebych minutissimus sp. n., male (A–E, G–I) and female (F, J–K). A–B prosoma, lateral and frontal; C eye group; D spinnerets and colulus; E posterior part of abdomen; F–H chelicera; I terminal part of cymbium with removed bulb showing cymbial spoor; J–K epigyne, ventro-lateral and antero-ventral. Scale = 0.1 mm, unless otherwise indicated. Abbreviations: Cl colulus, Cs cymbial spur, Ep epigynal plate, MAP major ampulate gland spigot, Me median plate of epigyne, Oc copulatory opening, Ss strong seta of cymbial spur, Ts tracheal spiracle.

FIGURE 3. SEM images of the male palp of Glebych minutissimus sp. n. A–C intact, meso-ventral, ecto-ventral and ecto-dorsal; D–I expanded palp, different views. Scale = 0.1 mm.Abbreviations: Co conductor, Cs cymbial spur, Eb embolic base, Em embolus, Ma median apophysis, Mp anterior process of median apophysis, Sm serrate retrolateral margin, Ss strong seta of Cs, Tp retrolateral pit of tegulum.

FIGURE 4. Glebych minutissimus sp. n., male (A, B, D–G) and female (C, H–L). A prosoma, frontal; B tarsus IV; C palp; D leg I; E abdomen; F–G epiandrus (two individuals); H epigyne, ventral; I–J epigyne, antero-ventral; K epigyne and uterus internus, antero-ventral; L abdomen, antero-ventral. Scale = 0.1 mm. Abbreviations: Cd copulatory duct, Ea epiandrus, Gs gland spigot, Me median plate of epigyne, Oc copulatory opening Re receptacle, To tarsal organ.

FIGURE 5. Collecting habitats (A–B) and type locality (C–D) of Glebych minutissimus sp. n.