Hymenobelba exclamationis, Mahunka, 2010

Mahunka, Sándor, 2010, Two new species of Ameroidea (Acari: Oribatida) from Madagascar, Zootaxa 2631 (1), pp. 62-68 : 63-65

Hymenobelba exclamationis sp. nov.

( Figs. 1–6 )

Diagnosis. Body and legs partly covered by cerotegument. Prodorsum with longitudinal unpaired costula, bearing lamellar setae. Interlamellar setae long, arising near to each other. Sensillus very long, finely ciliate. All ten pairs of notogastral setae thin, long. Apodemes and epimeral borders short, partly reduced. Enantiophysis S present. Epimeral setae varying in length, setae 1b and 1c longest of all, directed forwards. Strong ventral neotrichy, some setae in the aggenital region dilated, others long, setiform. Claw of leg I long, much thinner than the others.

Measurements. Length of body: 818–900 µm, width of body: 415–510 µm.

Prodorsum. Rostral part narrow, rostrum conical with a pair of weak longitudinal laths and a pair of well observable lateral tubercles bearing rostral setae. Prodosum with an unpaired, long, distally dilated, strong lath ( Fig. 4 ), which possesses a rounded tubercle behind as a longitudinal mark of exclamation-shape. All four pairs of prodorsal setae long, thin, setiform, lamellar setae arising on the distal end of costuliform crest. Interlamellar setae inserted on small tubercles, very near to one another. All setae long, their length: le =ro> in> ex. A weak transversal line in interbothridial region present. Bothridium cup-shaped, sensillus very long, setiform, curving slightly distally, unilaterally ciliate.

Notogaster. Anterior margin of notogaster slightly convex, with a pair of very small humeral processes. Notogastral surface without lateral cavities. Ten pairs of notogastral setae, all filiform, mostly with bent or slightly flagellate distal end ( Fig. 1 ). Setae c 2 except setae p m uch shorter than the notogastral setae. Lyrifissures im located longitudinally, between setae la and lm.

Lateral part of podosoma. Prodorsum characteristically excavate behind the rostrum and in middle part. Pedotecta I very large, rounded distally. Tutorium absent. Pedotecta II very small, triangular. Enatiophysis S large, triangular, its distal part bent outwards. Setae 3c arising on its basis.

Ventral parts. Epimeral region weakly sclerotised, without well developed structure. Only sejugal and apodemes IV visible, sejugal one strongest of all. Sternal apodeme absent. Length of setae highly varying, setae 1b and 1c longest of all, setae 1a and 2a shortest of all. Setae 3c arising on the enatiophysis ( Fig. 3 ), seta 4b and 4c located near to each other. Epimeral setal formula: 3-1-3-3. Genital setae arising in longitudinal rows. Aggenital and adanal neotrichy present. Some setae in median part of ventral plate dilated basally. Anal setae arising medially on two weak longitudinal crests. Lyrifissures iad located far from the anal aperture.

Legs. All legs conspicuously thin and long, monodactylous. Claws on legs I thinner and smaller than on legs II–IV ( Figs 5–6 ).

Remarks. The new species is well characterised by the presence of the prodorsal sculpture, by the form and length of the prodorsal and notogastral setae, by the distance of the lamellar and interlamellar ones and finally by the absence of the notogastral cavity. Considering most of these features Hymenobelba exclamationis sp. nov. stand nearest to H. ypsilon Balogh, 1962 , however, the prodorsal structure of the new species is much simpler than the others.

Material examined. Holotype: Malagasy Republic, Toamasina Province. Maromizaha forest . 26. August 1998. Leg. Dr. T. Pócs (9890) (Afr-923)). 2 paratypes from the same sample . Holotype (1784-HO-10) and 1 paratype (1784-PO-10) deposited in the HNHM, 1 paratype in MHNG .

Etymology. The name refers to the presence of a longitudinal mark of exclamation-shape (signum exclamationis) median costula in the interlamellar region.

Figures

FIGURES 1–6. Hymenobelba exclamationis n. sp.: 1. body in dorsal view; 2. body in ventral view; 3. epimer 3 with enantiophysis S; 4. anteromedian part of prodorsum; 5. claw of leg I; 6. claw of leg IV.