Asca nelsoni sp. nov. is described from Costa Rica, from within domatia on leaves of coffee plants, Coffea arabica L. (Rubiaceae), and compared with morphologically similar species A. brachychaeta Hurlbutt, A. citriHurlbutt and A. elongata (Berlese).
A new species of Asca von Heyden (Acari: Mesostigmata: Ascidae) was discovered during a survey of mites occurring in the domatia of Coffea species at the International Coffee Germplasm Center of the Centro Agronómico Tropical de Investigación y Enseñanza (CATIE) in Turrialba, Costa Rica (Vega et al. 2007). Members of this genus are predatory on other mites (Moutia 1958), eggs of insects (Moussa 1956), nematodes and other arthropods (Walter 1988; Epsky et al. 1988), and Collembola (Karg 1961; Hurlbutt 1963). They have been reported on the leaf domatia of several plants (Walter & O'Dowd 1992; Walter 1996), as inhabitants of the phylloplane (Walter et al. 1993), in bark beetle galleries (Stone & Simpson 1991), termite's and bird's nests (Ryke 1961), soil and moss (Ryke 1961), etc. Species of Asca are often abundant on the leaves of trees and lianas in subtropical to tropical rainforests, and several members of the genus truly prefer arboreal habitats (Walter et al. 1993; Lindquist et al. 2009).
One interesting aspect of the new species from the coffee domatia is the presence of germinated fungal spores on its cuticle (Vega et al. 2007). We have found no other reports of fungal spores on the body of other Asca species, although these have been reported on several other mites, including species of Tarsonemidae, e.g., Daidalotarsonemus deleoni (Smiley), Fungitarsonemus lodici(DeLeon), F. peregrinus (Beer), Tarsonemus floridanus (Attiah), T. scaurus Ewing, T. solengrandisOchoa, and Xenotarsonemus vargasi Ochoa (Ochoa et al. 1991). We hereby present a description for the new Asca species, A. nelsoni.
Material and methods
Measurements in micrometres (μm) were made from specimens flattened on microscope slides using a stage-calibrated ocular micrometer, and are presented in parentheses as ranges (minimum to maximum). Morphological features, unless stated otherwise, were measured as follows: inside edge of setal base to inside edge of setal base, i.e. the shortest distance between two setal bases; palps measured from base of trochanter to tip of tarsus; subcapitulum measured down midline from base to level with tip of corniculi; fixed digit of chelicera length measured from dorsal lyrifissure to tip, movable digit measured along maximum length down midline; spermatodactyl shaft length measured from membranous juncture with movable digit to tip of shaft; setal length measured from midpoint of insertion to tip. The term ‘pore’ used in descriptions is applied to all pore-like structures, and includes both sense organs (lyrifissures, id1-x) and gland pores (gd1-9) (sensu Ragusa & Athias-Henriot 1983). Gland pores are slit-shaped and lyrifissures are generally ovoid. Adult idiosomal chaetotaxy follows that of Lindquist & Evans (1965), and our generic concept of Ascafollows that of Lindquist & Evans (1965) and Lindquist et al. (2009).
List of Abbreviations
Mite Collection at Museo de Insectos, San Pedro, Universidad de Costa Rica, Costa Rica
United States National Mite Collection, US National Museum of Natural History (Smithsonian), Systematic Entomology Laboratory (SEL), Beltsville Agricultural Research Center West (BARC West), United States Department of Agriculture (USDA), Building 005, 10300 Baltimore Ave, Beltsville, Maryland, USA, 20705
Genus Asca von Heyden
Dorsal shield divided, with pair of posterior projections (horns) on opisthosomal shield usually bearing setae Z4 and S5 (Figs 1, 6). Female with expanded ventrianal shield incorporating 5–6 pairs of ventral setae (usually JV2-5, ZV2-3) in addition to circumanal setae (Fig. 2); genu I lacks ventral setae av-2 (i.e. 12 rather than 13 setae); third pair of sternal pores (stp3) on the sternal shield; fourth pair of sternal setae (st4) free on soft cuticle; movable digit of chelicerae usually bidentate (Fig. 3).
Types. Holotype. ♀. Costa Rica, Cartago, Turrialba, February 2005, ex. domatia on leaves of Coffea arabica L. (Rubiaceae) accession T.01997, International Coffee Germplasm Center, Centro Agronómico Tropical de Investigación y Enseñanza (N 09°54.012, W 083° 39.702), Fernando E. Vega (USNM).
Paratypes. Same data as holotype except ex. domatia on leaves of seven different accessions of Coffea arabica L. (Rubiaceae) (T.01994, T.01997, T.02248, T.02255, T.02268, T.02307, T.04492) (all on separate slides): 5 ♀♀, 2 ♂♂, deutonymph, 2 protonymphs, pharate larva (USNM); 2 ♀♀, ♂, 2 protonymph (MICR).
Anterior margin of tectum denticulate with 9–13 small teeth. Subcapitulum with 6–8 rows of 2–3 of deutosternal denticles (most commonly 7 rows of 2 denticles). Dorsal shields colliculate anteriorly; all dorsal setae inserted on small tubercles. Podonotal shield with 18–20 pairs of thick, densely spiculate setae; setae j1 similar in size to j2; setae r2 captured by shield, setae r3-r4 inserted in soft cuticle or rarely captured by shield. Opisthonotal shield with 15 pairs of densely spiculate setae (except Z4, J5 short, smooth) on raised insertions; J1-J1 = J2-J2 = J3-J3 = J4-J4; setae Z4significantly shorter than S5; J4-J3; UR2, UR4 present. Female ventrianal shield with six pairs of ventral setae (JV2-5, ZV2-3); setae JV4 and JV5 (inserted on posterior margin shield) and postanal seta longer, thick, barbed. Male ventrianal shield with seven pairs of setae (JV1-5, ZV1-2); setae ZV3 absent. Leg setae short, blunt.
Dorsal idiosoma (Fig. 1). Body measurements: j1-J5 (275–294), r2-r2 (120–125), s6-s6 (104–125), J1-J1 (10–14), J2-J2 (20–24), J3-J3 (16–20), J4-J4 (15–19), S1-S1 (115–123), S4-S4 (87–96). Two dorsal shields; all dorsal setae inserted on small tubercles. Anterior podonotal shield (j1-j6 114–129) colliculate-reticulate with 18–20 pairs of thick, densely spiculate setae: j1 14–16, j2 13–17, j3 18–21, j4 19–23, j5 17–23, j6 19–26, z2 20–27, z3 18–20, z4 19–23, z5 18–23, z6 21–25, s110–15, s2 18–25, s3 18–25, s4 19–23, s5 22–27, s6 23–29, r2 18–21, r3 17–21, r4 17–21. Setae r2captured by shield; setae r3-r4 inserted in soft cuticle or captured by shield; setae r5 (18–24) in soft cuticle laterad shield. Podonotal shield (J1-J5 122–126) with nine pairs of discernable pore-like structures, of which five appear secretory (gland pores: gd1 laterad j3; gd2 mesad z4; gd4 on shield margin laterad s5; gd5 posteromesad z5; gdx laterad j6) and four appear non-secretory (lyrifissures: id1 laterad j2; id1a anteriad j4; id4 on shield margin laterad s5; id6 laterad j6). Posterior opisthonotal shield ornamentation less pronounced than anterior shield, light reticulations anterolaterad from level with setae J1-S1 to J3-Z2; with 15 pairs of densely spiculate setae (except Z4, J5 short, smooth) on raised insertions: J1