Foveacorpus parvus, Bartel & Dunlop & Giribet, 2023

Bartel, Christian, Dunlop, Jason A. & Giribet, Gonzalo, 2023, An unexpected diversity of Cyphophthalmi (Arachnida: Opiliones) in Upper Cretaceous Burmese amber, Zootaxa 5296 (3), pp. 421-445 : 437-439

Species Foveacorpus parvus sp. nov.

Fig. 13

urn:lsid:zoobank.org:act:BC6852F1-9D85-46BF-9B15-EFF0F7230F9A

Holotype. Specimen GPIH05130 , ex coll. Patrick Müller, BUB3634.

Type-locality. Myanmar, Hukawng Valley; Burmese amber, Upper Cretaceous (Lower Cenomanian)

Etymology. The Latin adjective “parvus, -a, -um” (= small) refers to the small size of this species.

Diagnosis. Distinct from Foveacorpus cretaceus sp. nov. by its more pear-shaped body, smaller body size (less than 1mm), smaller tegumental pits and more bulbous ozophores.

Description. Body pear-shaped, subtriangular at anterior end and completely covered with small pits (diameter 0.011*); total L 0.82, maximum prosomal W behind ozophores 0.39, maximum opisthosomal W 0.48. Rounded ozophores probably in type 1 position. Distal part of left ozophore appearing bulbous ( Fig. 13A, C ). L of ozophores 0.09, W at base 0.10, distance between base of ozophores 0.26. Eyes equivocal. Chelicerae moderately long, finely granular on proximal segment; dentition equivocal; basal segment L 0.20, median segment L?, distal segment L?. Pedipalps small and thin; pedipalp length: tr?, fe 0.11, pa 0.03, ti 0.05, ta?. Legs relatively short, robust and granular; tarsus I not subdivided, bearing a single smooth claw and numerous setae; leg length: I tr 0.10, fe 0.19, pa 0.07*, ti 0.09, mt 0.10, ta 0.12, total 0.67; II tr?, fe 0.18, pa 0.06, ti?, mt?, ta?; III tr?, fe?, pa 0.10, ti 0.10, mt?, ta?; IV tr?, fe 0.16, pa 0.10, ti 0.10, mt 0.07, ta?. Ventral side of opisthosoma also covered with numerous small pits. Possible spiracles indicated by a few small denticles situated posterior to coxa IV. Anal plate rounded, with few small pits and with a corona analis, W 0.12, L 0.07 ( Fig. 13B, D ).

Remarks. The developmental stage of the holotype of Foveacorpus parvus sp. nov. (GPIH05130; Fig. 13A– D ) is difficult to assess because important characters like the gonostome or tarsus IV are obscured. Due to its strong sclerotization and dark colouration the fossil presumably is an adult. Nevertheless, this is another interesting specimen whose body is completely covered with small pits similar to those observed in the holotype of Foveacorpus cretaceus sp. nov. (GPIH05129; see above). Many of these pits seem to be open and originally preserved on the ventral side of the body ( Fig. 13B ). Therefore we again exclude the possibility of an artefact. Additionally, both congeneric specimens possess a corona analis and granular legs ( Fig. 13B, D cf. Fig. 11D ). A modified right leg III as in specimen GPIH05129 cannot be observed in this fossil. Furthermore, GPIH05130 is smaller, features more bulbous ozophores and a more subtriangular anterior margin of the dorsal scutum. Based on these differences GPIH05130 is associated with a different new species.

Figures

FIGURE 11. Foveacorpus cretaceus gen. et sp. nov., female holotype (GPIH05129). A. Whole body, dorsal view. B. Same, ventral view. C. Camera lucida drawing of A. D. Same of B. Abbreviations: ca, corona analis; ch, chelicerae; oz, ozophore; pp, pedipalp; legs numbered from I–IV. Scale bars equal 0.5 mm.

FIGURE 13. Foveacorpus parvus gen. et sp. nov., holotype of unclear sex (GPIH05130). A. Whole specimen, dorsal view. B. Same, ventral view. C. Camera lucida drawing of A. D. Same of B.Abbreviations: ap, anal plate; ca, corona analis; oz, ozophore; legs numbered from I–IV. Scale bars equal 0.2 mm (A–B) and 0.5 mm (C–D).