Posted by Librarian on 4/2/2002, 12:22 pm

Taxonomic Considerations. This mite belongs to the family Epidermoptidae, which may be easily distinguished from its nearest ally, the family Psoroptidae, by the fact that the females of the Epidermoptidae possess suckers on all the tarsi, whilst females of the family Psoroptidae have long whiplike setae on the third tarsi. Dermatophagoides Bogdanow, 1864 Dermatophagoides Bogdanow, 1864. Bull. Soc. Imp. Nat. Moscou 37 (1): 341-348, pl. 7, figs. 1-2.--Vitzhum, 1929. Tierreich Mitteleuropas, Acar, Bd. 3, 1f. 3,102--Sasa, 1950. Japanese Journal of Experimental Medicine 20:519-525. Pachylichus Canestrini, 1894. Prospetto del' Acarofauna Italiana, fasc. 6:824-829, pl. 77, figs 1-4.--Berlese, 1897. Acari, Myriopoda, Scorpiones, Cryptostigmata, Sacroptidae, fasc. LXXXII, no 12.--Oudemans, 1904, Ent. Bericht. 20:190-195 (synonomy with Dermatophagoides.) Mealia Berlese, 1897. Acari, Myriopoda, Scorpiones, Cryptostigmata, Sarcoptidae 1:104.--Berlese, 1898. Idem., fasc. LXXXIX, no. 10, and XCII, no. 3 and no. 4--Canestrini and Kramer, 18999, Das Tierreich, Demodicidae and Sarcoptidae, 137-138.--Trouessart, 1901, Bull. Soc. Zool. France XXVI:82-84. Viscopteres Sasa, 1947. Nisshin Igaku 34(3):167-170. Type: Dermatophagoides scheremetewskyi Bogdanow, 1864. Bogdanow described two forms of mites. The first of these, designated D. scheremetewskyi, is a female, depicted in dorsal and ventral views in figs. 1a and 1b. It occurred on the surface of the skin of humans suffering from the itch. The mite of the second type, found on a single occasion on a child suffering from herpes farinosus, and designated by Bogdanow as "Acarus de l'Herpes farinosus," is depicted in figs. 2a and 2b. It is a male, very probably that of D. scheremetewskyi as Bogdanow himself suggested; certainly it belongs in the same genus as the previously described female mite. Bogdanow compares his new genus with Dermatophagus, saying that it has "une grande resemblance ave selui des acriens due genre Dermatophagus, decrit en detail par Furstenberg." He notes two differences between Dermatophagoides and Dermatophagus: (1) the conformation of two lyre-shaped chitinous arcs near the genital opening of the female; and (2) differences in the termini of the third legs of the females. (Dermatophagus Furstenberg, 1861, is a synonym of Chorioptes Gervais, according to Ewing, 1929.) Dr. Menber, an M.D., reports on the finding of a species of parasitic mite infesting the human skin and causing a sever dermatitis. This mite he describes and figures, as: "Acarus incapsulator or Sarcoptes trichogenetos (Boeking)." The mite is said to have been found also in capsules beneath the skin of the same patient and was thought to be related to or be the causative agent of trichinosis, hence the specific name applied to it. North American records are: Texas; in a house in Kentucky; from a rat in Florida; from a house in Chester, N.H., causing an itch; and from New York. These, combined with the European distribution, indicate a rather widespread range and eventually the mite should be found throughout most of the world. Several other species have been placed in Dermatophagoides, but much work is needed before the exact status of the various species can be determined with certainty. Dr. Manabu Sasa, of the Institute of Infectious Diseases, University of Tokyo, Japan (The Japanese Journal of Experimental Medicine, vol. 20, pp. 519-525, 1950), discuss the genus Dermatophagoides in Japan. D. saitoi (Sasa) was taken in sputum of a patient with typical Loeffler's syndrom, D. takeuchii was found in urine, and an undertermined species was obtained from a patient with chronic bronchial asthma. Generic characters. Body oval. Dorsal shield present. Prominent transverse groove anterior to middle of body, the two hind pairs of legs posterior to this groove. Sexual dimorphism evident, especially noticeable in legs of male; however, all legs in both sexes are well developed. Posterior end of body more or less rounded, not lobed in either sex. A pair of copulatory suckers present on anal plate of male. Genital openings of female between third coxae; surrounded by a crescentic anterior and two curved lateral sclerotized supports. Corresponding opening of male somewhat more posterior, lying between fourth coxae. Penis short, conical. Epimera of first legs not united. All tarsi in both sexes with short terminal stalks (peduncles) which bear cup-shaped suckers. Claws, where present, small and not easily discernible. Two pairs of long, strong posterior setae, the outer pair longer. One pair of vertical setae, also long and strong, arise from anterior portion of dorsal shield. Chelicerae powerful, terminating in paired chelate cutting surfaces which are dentate on the inner margins. Legs I and II directed forward; legs III and IV directed backward. Dermatophagoides scheremetewskyi Bogdanow Dermatophagoides scheremetewsky Bogdanow, 1864. Bull. Soc. Imp. Nat. Moscou 37(1):341-348. Mealia pteronyssina Berlese, 1897. Acari, Myripoda, Scorpiones, Cryptostigmata, Sarcoptida 1:104. Acarus incapsulator Menger, 1896. Texas Medical News, San Antonio, Texas, Sept. 24:1-20 (attributed to Boeking). Sarcoptes, trichogenetos Menger, 1896. Texas Medical News, San Antonio, Texas, Sept. 25:1-20 (attributed to Boeking). Eleven females and nine males, all adults, were available for study. Three of the females, taken alive, were observed before being killed. On larva and two nymphs are also present in the available material. Mites were mounted (a) in clarite, after clearing in xylol, or (b) in modified Berlese's medium, usually direct from 35% alcohol. Some mites were cleared in KOH previous to mounting; others, including most of those mounted by the second method, did not undergo such preliminary treatment. Male mites are almost transparent, but female mites, unless cleared, show well only such structures as are on the surface which is uppermost. Certain morphological features are seen more clearly in mites mounted by the first method; others, by the second. Size. Female: 10 specimens measured. Average length, 355.2 u, from tips of mouthparts to tip of abdomen; average width 196.8u. Longest, 400u; shortest 320u; widest 240u; narrowest 160u. Male: 8 specimens measured. Average length 296u; av width 180u. Longest: 352u; shortest 256u; widest 208U; narrowest, 128u. Mouthparts. See Plate III, figs. 15, 16, 17, 18 and 19. These are quite complicated, heavily sclerotized, and interpretation of some of th parts is difficult. Two large chelicerae are present, each bearing distally a pair of cutting surfaces, the inner margins of which are dentate or serrate, as indicated in figures 15, 16, 17 and 18. From ventral view, two large triangular or conical structures are seen; from beneath these, the cutting surfaces are visible. Perhaps these represent a bilobed hypostome or rostrum. These structures are shown in the ventral views of male and female mites, Pl. I, figs. 3 and 4. Viewed from above, a very similar pair of triangular structures lying directly beneath the basis capituli almost obscures the cutting surfaces, which can be seen only by focussing downward. These are perhaps the basal portions of the chelicerae, on which the cutting surfaces are bone. It appears, then, that there are two sets of sclerotized, conical sturcutres, on pair dorsal, the other ventral, with the cutting surfaces between them, and attached to the uppermost pair of sclerotized cones. A pair of well-developed palps is present, on palp lying on each side of the conical structures. Each is four-segmented, if the basal segment <CLIP from this page (15) to page 22> One mite was kept alive for two days, at the end of which period it was as lusty and active as when first caught. Immersion in water, in which the cotton was kept moist, did not seem to disturb the mite. Occasionally a mite would leave the cotton and try to crawl about on the floor of the watch glass, but made little progress. One mite was killed in warm, not hot, water in which it died very quickly. A second was immersed in lysol solution of the strength used for treatment of the scalp. For 30 seconds it swam actively, then became quiescent. At 45 seconds, no movement could be detected. It is thus evident that the mites are susceptible and easily killed, if the killing substance can be brought into contact with them. But when in or under the epidermis, they are well protected. Opportunity is taken here to mention a similar situation in which another mite, Bdellonyssus sylviarum (C.&F.), family Laelaptidae (Dermanyssinae) was the causative agent. Several years ago a Mrs. X wrote me in regard to a difficulty which she and other members of her family had been experiencing. They had been suffering considerably from the attacks of an unknown "something" which was present on their scalps and bodies, and which they had been unable to eradicated. Mrs. X, on the advice of her physician, had consulted a dermatologist, who told her she was merely suffering from a "phobia" and to go home and forget it. Two days later, Mrs. X was fortunate enough to capture two dead mites that fell from her scalp. These she took to the dermatologist, who now became interested in her case, and prescribed some lotion as a treatment. Meantime he sent the two mites off for identification, and in due time they came to me. I believed them to be Bdellonyssus sylviarum, but sent them to Dr. Edward W. Baker for confirmation. He concurred in the above identification.