APLODONTOPHILA, A NEW GENUS OF CHIGGERS (ACARI: TROMBICULIDAE) FROM THE NORTHWESTERN UNITED STATES'

J. Med. Entomol. Vol. 18. no. 5: 395-400 30 September 1981 1981 12.!, the Bishop Museum APLODONTOPHILA, A NEW GENUS OF CHIGGERS (ACARI: TROMBICULIDAE) FROM THE NORTHWESTERN UNITED STATES' William J. Wrenn' and Chris Maser' Abstract. A new genus, Aplodontophila, is proposed for 2 species: the type species, Trombicula aplodontiae off Aplodontia rufa from Washington, and Aplodontophila pacifica, n. sp. off A. rufa from Oregon. Brennan (1946) described Trombicula aplodontiae from the Mountain Beaver, Aplodontia rufa (Rafinesque), in Washington. Numerous larvae of T. aplodontiae and of an undescribed but similar species were taken off Aplodontia rufa, collected along the Oregon Coast from 1970 through 1973. Studies of these 2 taxa have revealed that they represent a separate genus, distinct from but most similar to certain members of the subgenus Digenualaea Vercammen-Grandjean, 1960 ("microti" group of Brennan & Wharton 1950) of Neotrombicula Hirst, 1925. The descriptions of the new species and of T. aplodontiae are based on the holotypes, paratypes and other specimens examined. Numbers in parentheses under specimens examined refer to number of larvae examined and number of hosts if more than 1. All measurements are in micrometres, with those for the holotype followed in parentheses by the mean, range and sample size for other specimens. Aplodontophila Wrenn & Maser, new genus Type-species. Trombicula aplodontiae Brennan. Referred species. A. pacifica, n. sp. Diagnosis. Trombiculine larvae with palpal setal formula B/B/ BBB/7BS; palpal claw 3-pronged; galeala B; scutum hexagonal, 'This paper is a contribution, in part, of the Oregon Coast Ecological Survey, Puget Sound Museum of Natural History, University of Puget Sound, Tacoma, Washington 98416, USA. Department of Biology, University of North Dakota, Grand Forks, North Dakota 58202, USA. 3 Puget Sound Museum of Natural History, University of Puget Sound, Tacoma, Washington 98416, USA. (Present address: Forestry Services Laboratory, 3200 Jefferson Way, Corvallis, Oregon 97331, USA.) anterior margin concave, posterior margin broadly rounded, 3-sided, obscured b y encroaching cuticular striae; AW < SD: sensillae flagelliform, nude; legs 7-7-7 segmented; 2 genulae I, genuala II and III, tibia I with 9B, subterminala and parasubterminala I, tibiala III, nude or branched mastifemorala, nude mastitibiala, 2 nude or branched mastitarsalae. Description. Palpal setal formula B/B/BBB/7BS; galeala B; palpal claw 3-pronged. Cheliceral blade with tricuspid cap, cheliceral base strongly punctate. Scutum hexagonal; AW < SD; anterior margin strongly concave, prominent cuticular striae obscure a weakly defined, 3-sided posterior margin; prominent ridge anterior to SBs; 5 scutal setae, AM 4 AL < PL; sensillae flagelliform, nude; SB posterior to PL bases. Eyes 2/2 in ocular plate or absent. Legs 7-7-7 segmented. Nonspecialized branched setae on legs I to III. Coxa 1-1-1, trochanter 1-1-1, basifemur 1-2-2, telofemur 5-4-3, genu 4-3-3, tibia 9-6-6, tarsus 22-16-15. Internal annulations of genu, tibia and tarsus of all legs 1, 2, 2, respectively. Onychotriches absent. Remarks. Asanuma (1959) erected the subgenus Tsutsugamushia with Trombicula blumbergi Asanuma, 1959, as the type species. He also included T. aplodontiae in the subgenus on the basis of encroach- ment of cuticular striations over the posterior margin of the scutum and the presence of 2 mastitarsalae. Although Vercammen-Grancljean & Langston (1976) transferred T. blumbergi to the genus Toritrombicula Sasa, Hayashi & Kawashima, they did not mention T. aplodontiae., Our studies of T. aplodontiae show that it is not a Toritrombicula and, therefore, is not congeneric with T. blumbergi. Aplodontophila differs from Toritrombicula in possessing a subterminala on the palpal tarsus (lacking in T. blumbergi), a branched galeala (nude in Toritrombicula), SB posterior to PL bases (rather than anterior), nude sensillae (branched on distal 1/2) and parasubterminala I usually nude (always branched). Aplodontophila appears most similar to Neotrombicula cavicola (Ewing, 1931) of the inicroti group. The microti group as defined by several authors (Brennan & Wharton 1950, Kardos 1954, Gould 1956) belongs in the subgenus Digenualaea Vercammen-Grandjean (1960), and is usuall y placed in the genus iveotrombicula. Features shared by Aplodontophila and N. cavicola include branched

396 J. Med. Entomol. Vol. 18, no. 5 palpal and galeal setae, nude sensillae, SB posterior to PL bases, PSB < ASB, posterior margin of scutum without median angle, and 9B on tibia I. It differs from N. cavicola and other species of Digenualaea in having a narrower, hexagonal scutum (pentagonal in Digenualaea), strongly concave anterior margin (biconcave or only slightly concave), prominent ridge anterior to SBs (lacking), and a 3-sided posterior margin obscured b y encroachment of striae (2-sided, no encroachment of striae). Differences in scutal proportions and other features for Aplodontophila and Digenualaea include the following: AW < SD (AW SD); SD/PSB > 4 (<4); AM < AL < PL (AM = AL < PL). The name Aplodontophila refers to the affinity of the larvae for Aplodontia rufa. 24; microgenuala I, 6, 5-8, 11; microtibiala I, 6, 5-8, 13. Since the mastisetae were broken or obscured, it was not possible to obtain reliable measurements and as a result only those of the holotvpe are given (Fig. 2F). Specimens examined. 222 larvae, all from Aplodontia rufa except as noted below. USA: CALIFORNIA: Humboldt Co., 111.1960 (1). Mono Co., 26.V111.1940 (1). Placer Co., 3-.2 km NE Kings Beach, 23-24.VI.1951 (10/2). OREGON: Coos Co., 6.4 km SE Bandon, 14-29.X.1970 (8/3), 5.XI.1970 (9), 13.VII.1971 (7), 15-24.X11.1971 (12/2), 11.1.1972 (10); 12.9 km NNE Bandon, 23.X1.1970 (1). Curry Co., 16.1 km E Brookings, 21.IV.1972 (2); 16.1 km ESE Port Orford, 14.VII.1970 (10); 3.2 km S Port Orford, 20-26.XII.1970 (47/6). Douglas Co., 0.8 km N Gardiner. 1.111.1972 (18/2). Klamath Co., Crater Lake National Park, 5.IX.1946 (I). Lincoln Co., Cascade Head Expt'l Forest, 522.IV.I971 (33/5), 4X111.1971 (10). Tillamook Co., Cascade Head Expt'l Forest, 11-17.1V.1971 (31/4). WASHINGTON: King Co., 15-26.VIII.1945 (16 paratypes/3), 12-15.IX.1945 (holotype + 2 paratypes/2), 12X111.1945 (Mustela frenata 1 paratype). Snohomish Co., Monroe, 10.V1.1957 (I). Aplodontophila aplodontiae (Brennan), new comfig. 1 bination Remarks. Larvae of A. aplodontiae from all localities (Snohomish Co., Washington, south to Humboldt and Placer Counties, California) agree closely with each other and with the holotype. No significant differences of any character studied were observed among localities. Ecological notes. Larvae have been found on the ear pinnae of A. rufa in every month except Februar y. Aplodontia rufa occurs in British Columbia south through the western V3 of Washington and Oregon into the Coast Range (Marin Co.) and Sierra Nevada Mountains (Tulare Co.) in California. The only record of A. aplodontiae from a host other than A. rufa is the single larva from a Long-tailed Weasel, Mustela frenata, captured in an A. rufa burrow, as reported by Brennan (1946). No larvae were found on an y of the numerous small mammals from the same coastal Oregon localities where A. rufa harbored A. aplodontiae. Tromhicula aplodontiae Brennan, 1946: 443 (holot y pe from Aplodontia rufa (AP21994), King Co., Washington, 12.I V.1945).-Wharton & Fuller, 1952: 62.-Gould, 1956: 44.-Easton, 1975: 298. Trombicula (Tsutsugamushin) aplodontiae: Asanuma, 1959: 34. tarsala II; Diagnosis. Eves 2/2, with ocular plate, tarsala 1 nude mastifemorala, nude mastitibiala, 2 nude mastitarsalae: ger.uala and tibiala III < 20. Redescription of species (based on holotvpe with differences among paratypes and specimens listed in parentheses). Idiosoma 276 x 228, slightly engorged, orange in life. Eves 2/2 with ocular plate. Body setae. Dorsal setae 2-8-8-6-2-2, total 28; anterior setae similar to PLs, posterior setae with few short, stubby setules. Ventral setae 2-2 + 24 preanals and 8 postanals, total 36. Setal measurements: humeral, 75 (75, 71-81, 23); medial of 1st posthumeral row, 74 (78, 71-89, 26); posterior dorsal, 51 (50, 45-57, 27); 1st sternal. 53 (54, 47-55, 25); preanal, 48 (54, 47-61, 26); postanal setae similar to posterior dorsal setae. Scutum. Conspicuously punctate. anterior margin strongly recurved, posterior margin obscured by cuticular striae; sensillae flagelliform, nude: AM setules short, stubby; AM 4 AL < PL. Scutal measurements: ANN', 50 (50, 45-56, 21); PW, 71 (77, 7183, 23); SB, 24 (26, 21-28. 26); ASB, 47 (47, 44-49, 18); PSB, 11 (10, 9-13, 21); AP, 38 (39. 36-45, 17); AM, 38 (40, 34-46, 24); AL. 71 (73, 67-85, 24): PL, 85 (85, 78-95, 26); S, 85 (84, 69-99, 15). Gnathosoma. Palpal setal formula B/B/BBB/7BS; galeala B. Legs. All leg segments conspicuously punctate. Leg index of holotvpe: I, 314; II, 291; III. 368; total 973. Positions of branched setae and measurements and positions of nude setae as in Fig. 1 D-F. Parasubterminala 1 nude (occasional) forked or with 2 branches). Measurements (mean, range and sample size) of selected nude setae of specimens from throughout the range: subterminala 1, 28, 25-33, 25: tarsala I, 21, 1924. 26: tarsala II, 19. 18-20, 26; proximal tibiala I, 16, 13-18, 25: distal tibiala 1, 14, 13-16. 23; proximal tibiala 11, 12, 1214. 25; distal tibiala II, 12, 11-13. 26; tibiala III, 13, 11-14, 27: dorsal genuala I, 20, 19-24, 18; postermentral genuala I, 20. 19-22, 19; genuala II, 15, 12-20, 20; genuala III, 14, 12-15, Aplodontophila pacifica Wrenn & Maser, new species FIG. 2 Diagnosis. Eyes absent: mastifemorala and 2 mastitarsalae with branches; genuala and tibiala III > 20. Description of holotype (differences among paratypes listed in parentheses). Idiosoma 230 x 186, slightly engorged, white in life. Eves absent. Body setae. Dorsal setae 2-6-4-4-4-4-2, total 26; anterior setae similar to PLs, posterior setae with numerous short setules. Ventral setae 2-2 ± 22 preanals and 8 postanals, total 34. Setal measurements: humeral, 78 (78, 72-83, 27); medial of 1st posthumeral row, 82 (78, 76-83, 26); posterior dorsal. 49 (48, 42-53, 26); 1st sternal. 57 (53, 50-59, 23); preanal, 51 (53, 47-57, 26): postanal setae similar to posterior dorsal setae. Scutum. Conspicuously punctate. anterior margin strongl y concave, posterior margin obscured by cuticular striae; sensillae flagelliform, nude; AM setules long, thin, AM 4 AL < PL. Scutual measurements: AW, 38 (38, 34-41, 21); PW, 62 (61, 57-65. 23); SB, 19 (19, 17-22, 26); ASB, 45 (43, 39-45, 21); PSB, 11 (11, 9-12, 25): AP, 35 (34, 34-38, 22); AM, 46 (45, 42-47, 25): AL, 59 (61, 57-66, 24); FL, 71 (72, 68-78, 27); 1981

Since )le to,f the ccept 1960 sings n SE (7), don,,972 Port :rdiark, 5 :ade )N: 945 2 1 alm- if- b- ia r- 3. no. 5 1981 Wrenn & Maser: New chigger genus from USA 397 e FIG. 1. Aplodontophila aplodontiae (Brennan): A, scutum and eyes; B, dorsal aspect of gnathosoma; C, ventral aspect of palpal tibia and tarsus; D, distal 3 segments of leg I showing specialized setae and bases of other setae (measurements in Ilm); E, leg II as above; F, distal 4 segments of leg III as above: G, posterior dorsal both seta.

398 J. Med. Entomol. Vol. 18. no. 5 FIG. 2. Aplotiontophila pacifica n. sp: A. scutum; B. dorsal aspect of gnathosoma; C, ventral aspect of palpal tibia and tarsus; D, distal 3 segments of leg I showing specialized setae and bases of other setae (measurements in E, leg II as above; F, distal 4 segments of leg III as above; G. posterior dorsal body seta; H, anterior dorsal body seta.

1981 Wrenn & Maser: New chigger genus from USA S, 107 (broken) (107, 99-117, 16). Gnathosoma. Pa1pal setal formula B/B/BBB/7BS; galeala B. Legs. All leg segments conspicuously punctate. Leg index of holotype: 1, 357; II. 338; W. 392; total 1087. Measurements and positions of selected nude setae as in Fig. 2, D F and as follows for paratypes: subterminala I, 28, 26-29, 24; tarsala I, 21, 20-23, 27; tarsala 11, 20, 19-21, 27; proximal tibiala I, 16, 14-17, 27; distal tibiala I, 15, 12-17, 27; proximal tibiala II, 13, 11-14, 27; distal tibiala II, 12, 11-14, 27; tibiala III, 22, 20-24, 23; dorsal genuala I, 28, 25-30, 20; posteroventral genuala 1, 28, 26-31, 23; genuala II, 25, 23-27, 25; genuala III, 25, 24-27, 22; microgenuala 1, 8, 7-8, 8; microtibiala 1, 7, 6-9, 17. Type data. Holotype larva and 5 paratypes, USA: OREGON: Tillamook Co., Cascade Head Expt'l Forest, off A. rufa, 16.IV.1971, R\IL 57835. 19 paratypes, Lincoln Co., Cascade Head Expt'l Forest, off 2 A. rufa, 5.IV.1971 (10 larvae), RML 57814; 7.VIII.1972 (9 larvae), RML 59839. All collected by Chris Maser. Holotype and selected paratypes will be deposited in the trombiculid collection of the U.S. National Museum of Natural History (currently housed at the Bishop Museum, Honolulu, Hawaii). Other paratypes will be deposited in the collections of the Acarology Laboratory, Ohio State University, Columbus, Ohio, and the Acarological Research Laboratory, California State University, Long Beach, California. Other specimens examined. 22 larvae, all from A. rufa. USA: OREGON: Curry Co., 3.2 km S Port Orford, 25.X11.1970 (2). Coos Co., 6.4 km SE Bandon, 13.1;11.1971 (3), 15.X11.1971 (1), 24.XII.1971 (1). Douglas Co., 0.8 km N Gardiner, 1.111.1972 (2/2). Lincoln Co., Cascade Head Expt'l Forest, 5-22.IV.1971 (9/3), 7.VI11.1972 (1). Tillamook Co., Cascade Head Expt'l Forest, 15.IV.1971 (3). Remarks. In addition to those generic characters noted above, A. pacifica resembles A. aplodontiae in most features examined. The palpal setae possess numerous setules, and, with 1 exception, the specialized setae of the legs occupy similar positions on their respective segments. It differs in lacking eyes (eyes 2/2 for A. aplodontiae) and in having a narrower scutum, AW < 42, PW < 68 (AW > 44, PW > 70), branched mastifemorala and mastitarsalae (nude), microtibiala I ventral to and in line with proximal tibiala I (slightl y ventral and distad of proximal tibiala I) (Fig. 1D, 2D), and genuala and tibiala III > 20 (<20). The species name is derived from the subspecific name of the Mountain Beaver, A. rufa pacifica, from which larvae were collected. Ecological notes. This species occurs along the Oregon coast (Tillamook, Lincoln, Douglas, Coos and Curry Counties) in March, April, Jul y, August and December, and larvae probabl y are on hosts throughout the year. Larvae have been found only 399 on the pinnae of 12 A. rufa; 11 of these also harbored A. aplodontiae. DISCUSSION Of 37 A. rufa examined for ectoparasites from coastal Oregon, 31 (84%) harbored 1 or more chiggers. Of these positive hosts, 30 (97%) were parasitized by either 1 or both species of Aplodontophila. All larvae were found on the ear pinnae. Other chigger species recovered included Neotrombicula cavicola (Ewing) (2 hosts), Euschoengastia brennani Wrenn & Loomis (2 hosts) and an undescribed species of Euschoengastia (3 hosts). The lack of records from other hosts suggests host specificity for both A. aplodontiae and A. pacifica. Daniel (1957), in a study of ecologic aspects of 3 species of Czechoslovakian trombiculids, suggested that the extent and intensity of larval infestations were determined by ecological specificity. Easton (1975) also suggested that A. aplodontiae may exhibit either an ecological specificity or a physiological dependency on the host. Additional studies are necessary to determine whether Aplodontophila species are host specific or whether both the chiggers and their host require similar factors (or portions thereof), such as those provided in the burrow. Acknowledgments. The following people loaned specimens of A. aplodontiae: D. P. Furman, University of California, Berkeley (larvae from California) and J. M. Brennan and M. L. Goff. Bishop Museum, Honolulu (types and other larvae from Washington. Oregon and California). R. B. Loomis, California State University, Long Beach, reviewed the manuscript. We are sincerely grateful for the help of these individuals. LITERATURE CITED Asanuma, K. 1959. A new subgenus and two new species of trombiculid mites, Trombicula (Tsutsugamushia) blumbergi n. subgen. et sp., and Neoschoengastia baylissi n. sp., from the Japanese birds. Misc. Rep. Res. Inst. Nat. Resour. 51: 34-43. Brennan, J. M. 1946. Two new species of Trombicula: T. montanensis and T. aplodontiae (Acarina. Trombiculidae) from northwestern United States. f. Parasitol. 32: 441-44. Brennan, J. M. & G. W. Wharton. 1950. Studies on North American chiggers, No. 3. The subgenus Neotrombicula. Am. Midi. Nat. 44: 153-97. Daniel, M. 1957. Ecology of trombiculid-larvae (Acari: Trombiculidae) on small mammals in low-lying country in Czechoslovakia. Cesk. Parazitol. 4: 85-111. Easton, E. R. 1975. Ectoparasites in two diverse habitats in western Oregon. 11. Chiggers (Acari: Trombiculidae). J. Med. Entomol. 12: 295-98. Gould, D. J. 1956. The larval trombiculid mites of California (Acarina: Trombiculidae). Univ. Calif Berkeley Publ. Entomol. 11: 1-115. Kardos, E. H. 1954. Biological and systematic studies on the subgenus Neotrombicula (genus Trombicula) in the central United States (Acarina, Trombiculidae). Univ. Kans. Sci. Bull. 36: 69-123.

400 I. Med. Entomol. Vol. 18. no. 5 Vercammen-Grandjean, P. H. 1960. Introduction a un essai de classification rationnelle des larves de Trombiculinae Ewing 1944 (Acarina-Trombiculidae). Acarologia 2: 469-71 Vercammen-Grandjean, P. H. & R. Langston. 1976. The chigger mites of the world. Volume 111. Leptotrombidium complex. Section B. Trombiculindus, Hypotrombidium & Ericotrombidium, plus heterogenera. G. W. Hooper Foundation, San Francisco: 613-1061. Wharton, G. W. & H. S. Fuller. 1952. A manual of the chiggers. Mem. Entomol. Soc. Wash. (4): 1-185. SPECIAL EDITORIAL NOTE TO OUR READERS The following explanation of our review and publication process ma y be of general interest to our readership. The time periods indicated below are those currently in effect, which we hope to be able to maintain. The period from first submittal to publication, in the case of a MS requiring only minor changes and that is expeditiously reviewed and promptly returned by the author, averages 9 months. Newl y submitted manuscripts are acknowledged immediatel y upon receipt and are sent to at least 2 extramural reviewers. Reviewers' anonymit y is maintained (unless the y prefer to identify themselves). Reviewers are asked to provide reviews within 3 weeks. The time interval between recept of MSS and completion of outside reviews is approximatel y 11/2 months; this period will be longer if alternate reviewers must be selected or if initial reviews are so widely disparate that additional review is required. When all reviews are received, the MS undergoes editorial review and editing. A decision regarding acceptabilit y and required revision is usually communicated to the author within 2 months of submission. The revision period depends primaril y on the author's expedience and on whether the necessary revision is relativel y simple and straightforward or involves major changes and/or further experimentation. When the revised MS is returned, it is reviewed again by the editor. Occasionall y, a revised MS is sent out for re-review b y a specialist; sometimes it is necessary to return a MS 2 or more times to the author for further modification. Once a paper is deemed acceptable, it is "copy-edited" for the printer. The average interval from return of a revision to formal acceptance for publication is about 1 month. The MS is then sent to the printer, along with all other papers constituting that issue. The scheduled interval from dispatch to the printer until publication is 51/2 months. This time period is governed largel y by requirements of the printing process, which include setting the MS into t ype and producing a 1st proof, which is read by author and editor, and a revised proof, which is checked b y the editor. After a period of dela yed publication, a situation exacerbated b y our transition from printing in Japan to a U.S. printer, JME has appeared on time or within a few weeks of scheduled publication (Jan., Mar., Ma y, July, Sept. and Nov.) since volume 15 (1979). Through the combined efforts of our editorial staff and Allen Press, we hope to be able to continue to deliver to our readers a timel y publication of high quality. the cac str fie in lar pa yie of ph kit 21 fil: At c1( al ar tic sf ez fa A fc a sr is u Sl it sl