FNZ 7 - Cryptostigmata (Arachnida: Acari) - Morphology
Luxton, M 1985. Cryptostigmata (Arachnida: Acari) - a concise review. Fauna of New Zealand 7, 112 pages.
(
ISSN 0111-5383 (print),
;
no.
07.
ISBN 0-477-06762-X (print),
).
Published 08 Dec 1985
ZooBank: http://zoobank.org/References/98C34746-C9D1-4CD1-8FD4-1115A3FAAFAB
Morphology
In dorsal view the body of a cryptostigmatid mite has two parts, the prodorsum and the notogaster. The prodorsum covers the propodosoma, and the notogaster covers the hysterosoma (Figure 1). The propodosoma may be folded on to the hysterosoma like the blade of a penknife, or articulated but not foldable, or immoveably attached. The prodorsum and the notogaster are separated by the dorsosejugal suture, which sometimes is interrupted medially or is completely absent.
Dorsal surface (Figures 1, 4, and 6)
Prodorsum.
This region bears 4 or 5 pairs of setae:
| (i) | sensilli (ss) |
| (ii) | interlamellars (in) |
| (iii) | lamellars (le) |
| (iv) | rostrals (ro) |
| (v) | exobothridials (ex) |
The sensilli are situated in an invagination, the bothridium (bo), which like the sensilli may sometimes be missing. The tip of the prodorsum is called the rostrum, and may bear teeth or incisions of taxonomic significance. Frequently, on each side of the prodorsum between the bothridium and the rostrum, there are thickened integumental extensions. If flat and raised above the prodorsum, or lamelliform and horizontally extended, they are known as lamellae (la) (Figures 8 and 9). If they are merely indistinct, rib-like ridges they are termed costulae. The lamellae are frequently connected by a translamella (trs), the costulae by a transcostula. The apex of a lamella is known as the cuspis (cu).
Notogaster (Figures 3, 5, and 7).
In the higher cryptostigmatids the notogaster generally bears 10-14 pairs of setae, whereas in the more primitive forms it usually has 16 or more. Lee (1981, 1982) is in the process of homologising chaetotaxy, but currently 3 different notations are used, as follows.
- Primitive cryptostigmatids with approximately 16 pairs of setae (Figures 1 and 2). Setal notation is in the order of the transverse rows:
row 1 : c1, c2, c3 row 2 : d1, d2, d3 row 3 : e1, e2 row 4 : f1, f2 row 5 : h1, h2, h3 row 6 : ps1, ps2, ps3 - Higher cryptostigmatids with 14 or 15 pairs of setae (Figure 4). The homology of some of the setal rows is uncertain. The notation for rows 1, 5, and 6 is retained, but for the others letters indicating relative position are substituted (e.g., d, dorsal; l, lateral; a, anterior; m, median; p, posterior):
row 1: c1, c2, c3, anterior row: da, la median row: dm, lm posterior row: dp, lp row 5: h1, h2, h3 row 6: ps1, ps2, ps3 - Higher cryptostigmatids with approximately 10 pairs of setae (Figure 6). The homology of the ps row is accepted, but other homologies are uncertain. Four setal groups are distinguished:
group t: ta, te, ti group ms: ms group r: rl, r2, r3 group p: pl, p2, p3
| areae porosae adalares: | Aa |
| areae porosae mesonoticae 1: | A1 |
| 2: | A2 |
| 3: | A3 |
The sacculi are small sacs below the cuticle with a minute opening to the surface. Their position and number correspond to those of the areae porosae, and their notation is Sa, S1, S2, S3. The pori are slit-like pores on the notogaster; their notation is prefaced by the letter i (viz ia, ip, ips, ih, im, iad -- Figures 1-3). The location of pori iad has taxonomic significance in some groups. If they are parallel with the edge of the anal plate they are said to be adanal in position, if obliquely inclined they are apoanal in position.
Sometimes the anterolateral edges of the notogaster are prolonged into a horizontal or ventrally curved integumental lamella known as a pteromorph. This may be hinged and moveable, or fixed (or only partly hinged) and immoveable. In some species the anterior edge of the notogaster is also extended into a thin projection, like the eaves of a house, known as a tectum. Chitinous teeth, ridges, or lines are sometimes to be found anterodorsally on the notogaster. These are collectively known as cristae.
Ventral surface (Figures 3, 5, and 7)
Epimeral regionAnteriorly, the infracapitulum and the camerostome contain the mouthparts. Posterolateral to these are the coxae of the legs, with the genital plates further posteromedially. The area delimited by the camerostome, the coxae, and the genital plates is known as the epimeral region, and is covered by 4 epimeral plates (= epimera): ep1, ep2, ep3, ep4. The epimeral plates are bordered by chitinous thickenings, the apodemata, of which there are 5: apo1, apo2, aposj (apodemata sejugales), apo3, apo4. Apodemata 3 are often absent as a consequence of the coalescing of ep3 and ep4. Setae arising from the epimera are identified by numbers indicating the precise epimere, and by letters indicating location on the epimere. The epimeral setal formula frequently has important taxonomic value.
Projecting laterally from between the legs are appendages called tectopedia. These are described and located as follows:
| tutorium (tu): | tectopedium I, anterior to leg I |
| pedotectum 1: | tectopedium 2, posterior to leg I |
| pedotectum 2: | tectopedium 3, posterior to leg II |
| discidium (disc): | tectopedium 4, posterior to leg III |
Genitoanal region
Posterior to the epimeral region is the genitoanal region. The genital and anal openings are usually protected by plates bearing setae, and may be closely adjacent or widely separated. Aggenital (ag) and adanal (ad) setae are frequently present.