Poronoticae with not plicate nymphs
An example of Poronoticae, Humerobates rostrolamellatus GRANDJ. (Humerobatidae, Circumdehiscentiae). (a) tritonymph in lateral view, partial, with the legs omitted. Only the posterolateral angle of the prodorsum BPD and the posterior part of the circumtrochanteral opening of leg II are shown. The microscupture made up of small humps on the large dosal shield of the opisthosoma is seen only behind setae da and la. (b) 1, microsclerite with the base of the seta c1 in an eccentric position (i.e. ‘microsclerite thrown off centre’; in green); 2-6, small areae porosae of the dorsal shield associated with setae da, la (twice represented), dp and dm, respectively. Only the base of the setae is seen.
– Comments. The large, dorsal shield of the opisthosoma is articulated on both sides with a smaller shield (or ‘opisthopleural shield’) encircling the opening of the exocrine, latero-abdominal gland gla (or ‘lateral opisthosomal gland’ or ‘opisthonotal gland’ or ‘oil gland’) (note: the gland is discerned through the cuticle and coloured red).
The dorsal shield bears twenty setae. Each seta is inserted on the border or in the vicinity of the border (Fig. b) of a small, concave upwards, round or oval area porosa (in yellow). The other notogasteral setae are inserted on the unsclerotized part of the cuticle, either directly (as the setae c3) or on a porous, oval or semi-circular microsclerite (in green). Microsclerites and areae porosae probably all have a secretory function (see Norton & Alberti, 1997).
The notogasteral chaetotaxy is of ‘unideficient’ type (Grandjean, 1949a, p. 216) as normally found in many Circumdehiscentiae with naked nymphs (data in Grandjean, 1953a, pp. 435-440). The pair of setae f1 of the opisthosomatic segment F (i.e. the setae close to the plane of symmetry of the body) are missing and the centro-dorsal setae (labelled da, dm and dp or d1, d2 and e1) are present, so that a total of 30 setae is detected. All the setae on the dorsal shield as well as pseudanal setae ps2 and ps3 are reduced in size and a bit curved backwards. In contrast, the setae of row c are elongated, thick and barbed phaneres with a roughly tapered distal extremity.
The lateral region of the opisthosoma is remarkable for the following features:
(a) the existence of five glabrous and irregularly outlined microsclerites on which muscles are inserted (for instance, three muscular bundles arise from the microsclerite γn).
(b) the development of an oblique plicature groove marked out by the previous microsclerites. The groove extends dorsolaterally behind the row of setae c. Dorsally its posterior wall is clearly more pronounced than the anterior one.
(c) the possession of a humeral organ oh located in front of the seta c3 (its role is unknown). It is shaped like a small portion of a sphere.
The sejugal furrow is visible only between the coxal sclerites II and III. Dorsally and ventrally it is almost completely deleted (at least in an individual as inflated as in Fig. a).
As usual in tritonymphs in the Circumdehiscentiae, the ventral side of the opisthosoma exhibits eleven pairs of setae, namely three pairs on the adanal sclerite AD, two pairs on the anal valve, one pair in the aggenital region (labelled ag) and five pairs on the genital sclerite.
– Abbreviations. h, row of notogasteral setae. la, lm, lp (also labelled cp, e2 and f2, respectively), laterodorsal notogasteral setae. ia, im, ip, ih, ips, cupule-shaped lyrifissures (strain detectors; cf. Barth, 1981). III and IV, circumtrochanteral openings of the third and fourth legs, respectively, bearing a pair of articular teeth ). (after Grandjean, 1970b).
