Myrmecarchaea sp.

Wood, Hannah M., Singh, Hukam & Grimaldi, David A., 2021, Another Laurasian connection in the Early Eocene of India: Myrmecarchaea spiders (Araneae, Archaeidae), ZooKeys 1071, pp. 49-61 : 49

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Myrmecarchaea sp.


Myrmecarchaea sp.

Material examined.

single specimen, voucher number BSIP41985 (collection details above), deposited in Birbal Sahni Institute for Palaeosciences in Lucknow, India.


Body length from endites to abdomen: 2.4 mm, but abdominal portion of exuvium is partially deformed (Fig. 1C View Figure 1 ). Carapace missing. Chelicerae texture with scales and also tubercles present at setal bases (Fig. 1E View Figure 1 ). Sternum and chelicerae setae white and thickly plumose. Posterior sternum tubercle absent (Fig. 1F View Figure 1 ). Sternum not fused to intercoxal sclerites, with thin suture separating the two. Intercoxal sclerites large, filling up the intercoxal space. Sternum length 0.52 mm and width 0.21 mm, narrow throughout (longer than wide) and not shield shaped (Fig. 1D View Figure 1 ). Pedicel 0.21 mm long and 0.18 mm wide. Spur on each lateral side of pedicel (Fig. 1F View Figure 1 ). Posterior of cephalothorax elongated with a large space (0.084 mm) between coxae III and IV compared to spaces between other coxae (e.g., 0.048 mm between coxae II and III), roughly twice the length (Fig. 1F View Figure 1 ). Labium with narrow, v-shaped notch at tip, not fused to sternum. Endite shape slightly convergent, following line of the labium, then converging at distal end around labium (Fig. 1D View Figure 1 ). Endites elongated to at least half the length of the cephalothorax, pointing downward around 45°, extending beyond the coxae. Patella IV with retrolateral bulge, unclear if present on other patella. Large tubercles absent on legs, leg texture with scales. Femur IV with distinct bend. Dorsal surface of femora with bump. Leg IV patella/tibia juncture straight, not hyperextended. Femur I base the same thickness as other femora (Fig. 1D View Figure 1 ). Femur I longest (2.05 mm), followed by femur II (1.60 mm), femur IV (1.37 mm), then femur III (1.05 mm). Trochanters entire. Leg spines absent. Chelicerae 0.80 mm long and 0.17 mm wide (at midpoint), anterior surface smooth, i.e., lacking spine, protuberance, or cluster of setae. Basal edge of chelicerae splayed out rather than with parallel edges. Slight constriction at basal edge just distal to splayed edge. 8-9 visible peg teeth present only on cheliceral promargin, peg teeth uneven lengths, not showing a pattern (e.g., short, long, short, long), with blunt tips rather than tapering (Fig. 1E View Figure 1 ). Longer peg teeth present, close to gland mound, and at least one peg tooth present that is anterior to main promargin row. Four teeth on cheliceral retromargin. Cheliceral stridulatory striae present, occurring in the basal 1/3 of chelicera, with a regular edge forming an oval patch. Stridulatory cusps present on pedipalpal femora, two visible on basal right femur and one on basal left, with distal remainder of femora obscured. Distal portion of chelicerae curved laterad, with distal tip tapering, rather than blunt (Fig. 1E View Figure 1 ). Cheliceral gland mound present, a pointed bulge on retromargin close to where closed fang tip would meet cuticle (Fig. 1E View Figure 1 ). Fangs evenly rounded, lacking increased curvature at tip. Abdomen 1.35 mm long, exuvium shape suggests abdomen was smoothly rounded, elongate, and lacks dorsal tubercles. Abdomen hairs thick, plumose, with tips blunt and club-like (Fig. 1C View Figure 1 ). Anterior lateral, posterior lateral, and posterior median spinnerets developed (Fig. 1C View Figure 1 ). Large sclerotized pits on abdomen absent. Dorsal and ventral sclerotization on abdomen anterior, forming a sclerotized circle around pedicel, with dorsal sclerite folded back due to molting process (Fig. 1C View Figure 1 ). Pedipalpal tarsus lacking prolateral and retrolateral brush of setae, and spines.