Bitabulata, Goldschmidt, 2008

Goldschmidt, Tom, 2008, Taxonomical, ecological and zoogeographical studies on anisitsiellid water mites (Acari: Hydrachnidia: Anisitsiellidae Koenike, 1910) from Madagascar, Zootaxa 1954 (1), pp. 1-120 : 76

Bitabulata gen. nov.

Typus generis: Bitabulata kelycoxae gen. nov. sp. nov. .

Derivatio nominis: Bi (Latin) — double; tabulata (Latin) — panelled, bearing planks; referring to the two characteristic dorsal plates.

Diagnosis: Idiosoma oval, relatively large, purple-brownish to dark bluish; extended dorsal sclerotization separated, in two large, closely attached plates, covering most of dorsum; anterior plate bears post-ocular setae, posteriorly fused with Dgl-4 and -5, Dgl-1, -2, -3, -6 and Lgl-1 to -4 on mid-sized platelets in relatively wide dorsal furrow; integument lined; lateral eyes oval, separated on each side, free under integument; ventral shield complete; coxal field fused, most sutures visible; Cx-I medially long, capitular bay relatively small; Cx-II laterally overlapping Cx-III; Cxgl-2 and -4 near anterior margin of Cx-III; suture between Cx-III and Cx-IV incomplete; Cx-IV nearly rectangular; insertion of leg-IV lateral to genital field; genital bay tight; Cx- IV with lateral ridge (mainly between insertion of leg-IV and latero-dorsal of Cx-III, in one species just lateral to Cx-III); lateral margin of Cx-IV not visible; genital field rectangular-oval, with three pairs of elongatedoval acetabula; Vgl-1 at caudal margin of Cx-IV, Vgl-3 and excretory pore always on ventral shield, Vgl-2 and -4 fused with caudal margin of ventral shield or lying closely posterior; legs without swimming hairs, bearing strong setae; claws of leg-I to -III with very fine dorsal and stronger ventral clawlet, leg-IV-6 terminal with very small peg-like setae and mid-sized sub-terminal seta; capitulum compact to elongate; palps strong.

Remarks: Within the Anisitsiellidae several genera or individual species have an extended dorsal sclerotization comprising two large plates: The monotypic genera Anisitsidartia Cook, 1966 from West Africa, Bharatonia Cook, 1967 , Paddelia Panesar, 2004 and Shivatonia Panesar, 2004 , from India, as well as Nilotonia (Mamersonia) scutata Cook, 1966 from Liberia (West Africa) and N. (Mamersonia) cascada Goldschmidt, 2004 from Costa Rica. However, all these taxa differ significantly in the organisation of the venter and gnathosoma (character state of Bitabulata in parantheses): In Bharatonia , Anisitsidartia , Shivatonia , Nilotonia (Mamersonia) scutata and N. (M.) cascada the ventral shield is not complete, leaving — at least in the females — a stripe of unsclerotized integument between Cx-IV and the postgenital sclerite, the lateral margin of Cx-IV is clearly visible (complete ventral shield in both sexes, lateral margin of Cx-IV indistinct); in Bharatonia Cx-I medially are extended to the genital field, medially separating Cx-III; Ac3 oriented at right angles to the medial axis of the genital field (Cx-III meet medially; Ac 3 in normal position parallel to the medial axis of genital field); the palps of Anisitsidartia are very small, the palps of Paddelia are very stocky, in Bharatonia and Shivatonia P5 is elongated (the palps represent the “normal” anisitsiellid type, with P4 elongated and P5 short). Bitabulata is most similar to Anisitsidartia , especially in the general shape of the coxal field (Cx-I to -III small, Cx-IV large; Cx-I and Cx-III medially approximate to each other, but not fused; lateral ridge on Cx-IV), but the following differences separate that genus from Bitabulata (character state of the latter in paranthesis): Antero-dorsal plate bears three pairs of glandularia (none); caudal margin of Cx-IV rounded (relatively straight); genital bay caudally diverging (tight); glands on third coxae absent (well developed); ventral shield with suture lines posterior to coxal field (ventral shield compact); excretory pore posterior ventral shield (incorporated in ventral shield); palp extremely small (‘normal’ size); and claws of leg-I to -III without clawlets (with clawlets). The shape of the venter of Bitabulata gen. nov. is somewhat similar to the ventral shield of some species of Platymamersopsis K. Viets, 1914 and Rutacarus Lundblad, 1937 . However, the relationships of the new genus within the Anisitsiellidae are unclear and will require phylogenetic analysis.