Pachylaelaps meganalis Halliday, 2005: 48

Mašán, Peter & Halliday, Bruce, 2013, A new genus and species of soil mite (Acari: Pachylaelapidae: Pachylaelapinae) from the Canary Islands, Journal of Natural History (J. Nat. Hist.) 48 (7 - 8), pp. 403-412 : 410-411

Pachylaelaps meganalis Halliday, 2005: 48 .

Material examined

One female (paratype), Hermanus, Western Cape Province, South Africa, suction sample from soil surface with clover, Oxalis sp., capeweed and grass, 28 August 1994, coll. T. K. Qin (in the Australian National Insect Collection, CSIRO Ecosystem Sciences, Canberra) .

Supplement to original description

Dorsal idiosoma ( Figure 1G ). Dorsal shield oblong to oval-shaped, dorsoventrally flattened, lateral margins bent towards ventromarginal surface; surface almost smooth, with some weak transverse lines in the posterior half. Shield with 29 pairs of setae, j1 minute, about 5 µm long; r3–r5 very short, 7–10 µm long; setae in central position intermediate and 19–23 µm long; longer and marginally inserted setae shortened towards the anterior margin of idiosoma: the posteriormost longest setae (S4) 80–85 µm long, other posterior elongated setae (S1, S2, Z2) 60–70 µm long and the shortest elongated setae in anterior region (s1–s5), 50–65 µm long. Bases of dorsal setae J1 widely separated, markedly anterolateral to J2; z6 markedly anterolateral to j6, z3 markedly anterolateral to s1.

Ventral idiosoma. Sternal shield 145 µm long, shorter than genitoventral shield (length of sternal shield / length of genitoventral shield 0.63); with distinct arch-shaped sculptural line. Genitoventral shield longer than wide (238 µm long and 204 µm wide), relatively large, with hyaline anterior margin greatly expanded and reaching close to the level of setae st2, and with posterior margin overlapping anterior edge of anal shield. Peritrematal shield with longitudinal sculptural line parallel to outer margin of peritreme. Metapodal shields absent if not fused with peritrematal–exopodal–parapodal complex. Unsclerotized ventrolateral integument with five pairs of setae (r6, Jv2−Jv4 and Zv3).

Spermathecal apparatus. Sperm induction pore on medial edge of coxa III, spermathecal tubes as in C. comatus , but longer and finer.

Notes

The redescription above includes some corrections to the original description. The minute dorsal setae j1 were not specifically mentioned in the original description, but they were wrongly illustrated as normal in length. Genu I in this species has 12 setae (2-5 / 3-2), not 14 (2-6 / 4-2) as originally described. The unsclerotized ventrolateral integument has two additional pairs of setae not illustrated by Halliday (2005) – one adjacent to the antero lateral corners of the anal shield as in C. comatus (Jv2), and another very short pair at the level of the posterior margin of coxa IV, also as in C. comatus (r6). Tarsus II does not have thickened spur-like setae in this species.

Halliday (2005) originally described this species in the genus Pachylaelaps . However, this placement is inconsistent with our present concept of Pachylaelaps , because the sperm induction pore in P. meganalis opens onto coxa III (coxa IV in Pachylaelaps ); it has 12 setae on genu I (13 in Pachylaelaps ); its corniculi are short and horn-like (long and sword-like in Pachylaelaps ); and the dorsal shield has 29 pairs of setae (30 in Pachylaelaps ). Pachylaelaps meganalis is here transferred to Chaetodellus because it is in good agreement with the diagnosis of the genus and, in addition to the diagnostic generic character states, shares with C. comatus the presence of a prominent arch-shaped sculptural line on the sternal shield with its posterior ends near setae st4 (this sculptural line can be rarely found also in other pachylaelapids).

Key to the species of the genus Chaetodellus gen. nov. (females)

1. Dorsal shield setae strongly heterogeneous in length, long marginal setae subequal in length, approximately four to five times as long as central setae ( Figure 1A ); J4 short, not reaching posterior margin of idiosoma; anterior margin of sternal shield with short, truncate projection between setae st1 ( Figure 1C ); genitoventral shield subequal in length and width; idiosoma larger, dorsal shield 525 µm in length......... Chaetodellus comatus sp. nov. Dorsal shield setae less heterogeneous in length, long marginal setae approximately two to three times as long as central setae, increasing in length posteriorly ( Figure 1G ); J4 long, reaching beyond posterior margin of idiosoma; anterior margin of sternal shield straight, with no specific structure between setae st1; genitoventral shield longer than wide; idiosoma smaller, dorsal shield 416–442 µm in length...................................................................... Chaetodellus meganalis ( Halliday, 2005) comb. nov.

Figures

Figure 1. Chaetodellus spp., females. (A–F). Chaetodellus comatus sp. nov. (A) Dorsal shield; (B) ventral idiosoma; (C) sternal shield, anterior portion; (D) epistome; (E) tarsus II, distal section; (F) tubes of sperm access system opened onto coxae III. (G) Chaetodellus meganalis, dorsal shield. Scale bars: 100 µm (A, B, F, G), 50 µm (C, D) and 25 µm (E).