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Sejida
Superorder Parasitiformes
Order Mesostigmata
Suborder Sejida
Cohort Sejina (Sejoidea)
Common names: sejines, sejids, uropodellids, ichthyostomatogasterids
Probability of Encounter: low, most species are associated with treeholes, nests and other patchy habitats; most have deutonymphs that are phoretic on insects.
Quarantine importance: low - as far as is known, all sejines are predators or scavengers.
Diagnosis. Mesostigmata with the female having a large genital shield usually bearing 6 to numerous setae, often bifurcate anteriorly, and covering the ovipore and an opening to a large, sac-like spermatheca; tarsus IV with well developed intercalary sclerite bearing setae av4/ pv4.
Body with moderate to extensive
hypertrichy, numerous gland openings, and often densely tuberculate. Adult female dorsally with podonotal and
pygidial shields (sometimes extensive) that may bear horns, and usually with mesonotal or
mesolateral shields; secondary hardening of the cuticle often obscures the
extent and number of these shields; with large ventrianal
shield (sometimes developed dorso-laterally and fused to pygidial shield);
usually large, free metapodal shields;.
Peritremes and peritrematal shields usually well developed, the latter
fused anteriorly to podonotal shield and sometimes producing a process over the
gnathosoma (vertex); lateral setae often on small platelets. and Sternal area not fully
sclerotised, but with seta-bearing platelets and often a shield bearing 2 pairs
of setae. Males tend to have more
consolidated body shields; the genital aperture is on an intercoxal shield and
is covered by a subcircular valve.
Phoretic deutonymphs have a cylindrical anal process and 1-2 dorsal
shields. Tarsus I sometimes with an
apicotarsus, with or without claws.
Tarsus IV with 20 or more setae, including setae av4 and pv4 on a well
defined intercalary sclerite.
Tritosternum with well developed base and separate laciniae. Hypostomal seta h1 flattened, often
scale-like; corniculi entire or bifid.
Palp apotele 2-tined. Chelicerae
chelate-dentate, slender with setiform pilus dentilis to massive without pilus
dentilis; movable digit without arthrodial corona or excrescences.
Similar
mites. Some Monogynaspida (e.g. Ascidae)
have posterior horns, but these species have entire sternal shields and never
more than 2 setae on the female genital shield. Other monogynaspines
(Microgyniina, some Uropodina, Heatherellina, and rare Dermayssina
e.g. Halolaelapidae, Saprosecans) have fragmented dorsal shields, but
all have sclerotised sternal regions, 0-1 pairs of setae on the female's genital
shield, and lack setae av4/ pv4 and the intercalary sclerite of tarsus IV.
Ecology
& Distribution. The Sejidae is the most
diverse family in the Sejida with ~30 described species of Sejus and 16 of Epicroseius,
as well as numerous undescribed species in both genera. Sejids are common litter inhabitants in
moist forests in the subtropics and tropics, especially in association with
rotting wood, but are much less common in the Holarctic Region. Species of Sejus and Epicroseius
are predatory on small arthropods and nematodes and have been collected from
decaying fungi on logs; wood mulch in gardens; litter around logs in
rainforests and wet sclerophyll; and suspended soils in the canopy. The chelicerae have small, serrate teeth and
the anal opening is small. Only fluids
of prey are ingested. Males use their
chelicerae to transfer a flask-shaped spermatophore to the anterior cleft of
the female’s genital shield. One to
four eggs are carried by gravid females.
Deutonymphs of Sejina have been found as phoretics on beetles and flies
and have a cylindrical extension of the anal opening that is used to attach to
the carrier. Five species of Uropodella
(Uropodellidae) have been described from the Americas and Africa, mostly
associated with woody habitats. Species
of Asternolaelaps (Ichthyostomatogasteridae), many undescribed, are
known from Europe, North and South America, Australia and New Zealand. They have massive chelicerae and bifurcate
corniculi that are used to bite-off and swallow pieces of fungi and small mites,
and enlarged anal openings for eliminating solid wastes.
References
Athias-Henriot
C. 1972). Gamasides Chiliens (Arachnides) II. Revision de la famille Ichthyostomatogasteridae Sellnick 1953
(=Uropodellidae Camin, 1955). Arquivos
de Zoologia Sao Paulo 22: 113-191.
Athias-Henriot C. 1977.
A new Australian mite, Archaeopodella scopulifera gen. et sp. n.
(Gamasida: Liroaspidae). Journal of
the Australian Entomological Society 16: 225-235.
Camin JH. 1955.
Uropodellidae, a new family of mesostigmatid mites based on Uropodella
lacinata Berlese, 1988 (Acarina, Liroaspina). Bulletin of the Chicago Academy of Sciences 10: 65-81.
Domrow R. 1957. Some Acarina Mesostigmata from the
Great Barrier Reef. Proceedings of the Linnean Society of New South Wales
81: 197-216.
Evans GO. 1954.
On the genus Asternolaelaps Berlese, 1923
(Acarina-Mesostigmata). Entomologists
Monthly Magazine 90: 88-90.
Gilyarov MS & Bregatova NG (eds) 1977.
Handbook for the Identification of Soil-inhabiting Mites,
Mesostigmata. Zoological Institute
of the Academy of Sciences: Petrograd [In Russian]
Johnston, D.E.
1982. Mesostigmata. In: Parker, S.P. (ed.) Synopsis and classification of living
organisms. McGraw-Hill, New York, p.
112-116.
Kethley JB. 1983.
Modifications of the deutonymph of Uropodella lacinata Berlese,
1888, for phoretic dispersal (Acari: Parasitiformes). Journal of the Georgia Entomological Society 18: 151-155.
Sellnick M. 1953.
Ichthyostomatogaster nyhleni, eine neue Acaride aus
Schweden. Entomologisk Tidskrift
74: 24-37.
Walter DE and Proctor
HC. 1998. Feeding behaviour and phylogeny: Observations on early derivative
Acari. Experimental and Applied
Acarology 22: 39-50.
Womersley H. 1959.
A new Asternolaelaps from Australia (Acarina,
Ichthyostomatogasteridae). Records
of the South Australian Museum 13: 355-358.