Ascoschoengastia (Laurentella) lorius (Gunther)

Shaw, Matthew, 2010, Post-larval stages of Ascoschoengastia (Laurentella) lorius (Gunther) (Acariformes: Trombiculidae) provide evidence for a nest-based life history, Zootaxa 2680, pp. 55-64 : 56-62

Ascoschoengastia (Laurentella) lorius (Gunther)

( Figs. 1–18 )

Neoschöngastia lorius Gunther, 1939: 86

Neoschöngastia lorius, Womersley & Heaslip : 118 Neoschöngastia lorius, Gunther 1952: 30

Euschöngastia lorius, Wharton & Fuller 1952: 78

Schöngastia (Ascoschöngastia) lorius, Womersley 1952: 207

Euschöngastia ( indica -group) lorius, Audy 1954 (1953) : 154

Euschöngastia (Laurentella) lorius, Audy 1956: 12

Ascoschongastia (Laurentella) lorius, Womersley & Audy 1957: 279

Ascoschoengastia lorius, Domrow 1974: 18 [partim, excluding Borneo specimens previously described as A. (L.) daria (Traub & Audy) ]

Description of larva ( Figs.1–5 ). Colour in ethanol white, colour in life unknown. Idiosoma of unengorged larvae subcircular 145–150 x 115–117. Eyes 2 + 2, subequal diameter, on ocular plate.

Gnathosoma: Cheliceral blade with tricuspid cap. Palpal formula B/B/BbB/5B. Two specimens with 5B on one side and 6B on other. Galeal seta nude, tapering. Palpal claw stumpy, 7 long, two unequal prongs.

Scutum : Anterior margin biconcave, pronounced shoulders. Lateral margin concave. Evenly and lightly punctate except smooth semicircular zone surrounding AM seta. Sensilla expanded, clavate, clothed in setules with distinct acuminate tip. Standard data presented in Table 1 .

Dorsal body setae: 2:6:6:4:2:2; DSL 21–24 long; DSA 23–25 long; DSP 21–24 long.

Ventral body setae: Ventral setae shorter, less ciliated than dorsally. VS: 10, 15–19 long; CS: 8, 18–20 long. 48 body setae in total, including humerals and four sternal setae.

Legs: Seven segments, coxae uniformly punctate. One setae on coxa I–III, mostly ciliated, 1 specimen ( Fig. 2 ) without cilia on coxal seta III and 3 specimens almost nude on II. Ciliated leg setae typically with cilia along length except distal third. Measurements, type and number of setae as follows: Leg I: 130–138 long. Tarsus I 42 x 17 with pretarsala, tarsala (11), microtarsala, subterminala, parasubterminala and 21–23 ciliated setae. Tibia I with two tibialae, one microtibiala, eight ciliated setae. The proximal tibiala set behind, i.e. directly proximal to microtibiala. Genu I with 3 genualae, microgenuala and 4 “ciliated” setae of which 1 sometimes lacks cilia. Telofemur I with 4 ciliated setae. Basifemur and trochanter I with 1 ciliated seta each. Trochanter I seta long (32), densely ciliated and curving. Leg II: 104 –111 long. Tarsus II 34 – 37 x 16–18. Tarsus with pretarsala, tarsala, microtarsala and 15–16 ciliated setae. Tibia II with 2 tibialae and 7 ciliated setae. Genu II with 1 genuala, 3 ciliated setae. Telofemur, basifemur, trochanter II with 4, 2, and 1 ciliated setae respectively. Leg III: 129 – 135 long. Tarsus III 43 – 45 x 13–15 with 14 setae all ciliated except 1 dorsobasal mastiseta 32–35 long. Tibia III with 1 tibiala, 6 ciliated setae, 1 dorsal seta almost nude in one specimen; genu III with 1 genuala and 3 ciliated setae. Telofemur, basifemur, trochanter III with 3, 2, and 1 ciliated setae, respectively.

Description of female ( Figs. 6 , 10 ). Colour in ethanol pale cream. Colour in life unknown. Small, (625– 640 long), elongate, weakly constricted between propodosoma and hysterosoma, clothed in simple ciliated setae which are shorter anteriorly (8–14) than posteriorly (13–20) ( Fig. 6–7 ).

Genital area ( Fig. 10 ) oval with flap-like weakly-sclerotised genital plates, 62–75 long, bearing 11–14 setae each. Anterior edge of genital plates at level with, or slightly forward of, posterior edge of coxa IV. Three pairs of subcircular to elongate oval acetabula on dorsal wall of genital atrium, shape variable according to mounting, 9–14 along longest axis, posterior pair slightly smaller than anterior 2 pairs. Most specimens with 4 pairs of nude genital setae. In 1 specimen, 5 pairs and in another 4th seta on one side having single cilium. No fan-shaped setae or sacculi (genital rings) present.

Anal plates narrow and elongate, 44–46 long separated by approximately their own length from genital area.

Gnathosoma : Chelicerae with continuous row of small teeth along dorsal surface, blade 32–36 long. Hypostome with 4 pairs of nude apical setae and 2 pores ( Fig 13 ; pores not visible in slide mounts) and 24–26 ciliated setae posteriorly, 12–14 of these in 2 parallel rows running ventromedially. Palp femur with 5 ciliated setae; 2 dorsal, 3 ventral. Palp genu with 7 setae, 2 to 3 of 4 dorsal setae nude. Palp tibia with 5 nude setae and 3 ciliated setae. Three tongue-shaped accessory setae flank base of tibial claw which is 17 long. Another tongue-shaped seta borne mediolaterally ( Fig. 9 ). Palp tarsus with 4 nude apical sensory setae, 13–14 ciliated setae, 1 basal sensory rod.

Idiosoma: Crista metopica with strong posterior apodeme. Sensilla narrowly lanceolate and heavily barbed. Tectum with single seta. Two parascutal setae at base of crista 20–26 long. Seven to 9 pairs ciliated seta anteriad sensillary area. Eyes absent. No precoxal complex between coxa I and II. Five to 6 ciliated setae between coxae I.

Legs. Leg formula 1>4>2>3. Leg I: Trochanter I with 5 long setae ca. 21–28, telofemur occasionally with single PT (pointed and tapering) seta. Genu I bearing ca. 22 PT setae, 14–16 long, and 5 medium length, blunt (MB) solenidia, 16–17 long and pointed microgenuala (2 long) and dorsodistal R seta ( Fig. 18 ). Tibia I bearing pointed microtibiala (3 long) on dorsodistal tip and 2 dorsodistally placed recurved (R) setae (12 long) with their tips directed away from leg surface as per tarsal recurved setae. Approximately 13 PT setae, 13–14 long and distinct in having their tips not curved away from leg. Tarsus I 84 –97 long, 32–40 high bearing five types of setae ( Figs 14–17 ): numerous ciliated setae 16–22 long; 14 elongate gradually-tapering LB (long and blunt) solenidia held closely parallel to tarsus (16–22 long; Fig. 15 ); ca. 46 R setae 7–10 long, sinuous with tips directed strongly away from tarsus ( Fig. 16 ); 2 short blunt (SB) seta (10–11 long) ( Fig. 17 ) and pointed microtarsala (ca. 2 long) ( Fig. 14 ).

Leg II: Trochanter II with 5 to 6 ciliated setae ca. 32 long. No sensory setae on basifemur. Telofemur with 3 PT setae (15 long). Genu II with 5 to 6 PT setae (13–14 long). Tibia II with 5 to 6 PT setae and 1 slender but blunt dorsodistal MB seta (13 long). Tarsus II with 2 SB setae (12 long) and pointed microtarsala (2 long).

Leg III: Trochanter with 6 setae ca. 31 long. Basifemur without sensory setae. Telofemur with 3 to 4 PT setae (13–14 long). Genu with 6 PT setae (14–15 long). Tibia with 4 or 5 PT setae (12–14 long). Tarsus III with 1 MB seta (16 long).

Leg IV: Trochanter IV with 12–14 setae ca. 26 long. Basifemur IV without sensory setae. Telofemur IV with 2 PT setae (15 long) and 1 dorsodistal R seta, mildly upturned tip. Genu IV with 8 to 9 PT setae (13 long) with 1 upturned R seta dorsodistally. Tibia IV with 8 to 14 PT setae (16 long) and 1 upturned R seta dorsodistally. Tarsus IV with 1 LB (19 long), 1 PT or R (13–16 long) seta and 2 PT setae (16–17 long).

Four females carrying between 1 and 3 ova, 68 –170 in diameter.

Standard data for females and males as follows: CTL 56 (52–61) ± 3; ASL 67 (62–80) ± 5; SB 32 (28–33) ± 2; PSL 17 (11–30) ± 3; PAD 32 (28–35) ± 3; ASL/SB 2.2 (2.0–2.6) ± 0.2; Sens 70 (63–75) ± 4; SS 23 (20– 26) ± 2; TS 18 (12–22) ± 3.

Description of male ( Fig. 11 ). Male similar to female, differences only noted in genital region. Genital plates 67 long bearing 27–35 pairs densely packed ciliated seta. Four pairs nude inner genital setae. Four pairs fan-shaped setae borne on low tubercle [= genital “papilla” of Wharton & Fuller (1952)]. Three pairs of acetabula, 9–14 long. Median sclerotised plate (operculum) of ejaculatory complex, exposed on only 1 specimen, measures 42 x 24 ( Fig. 11 ) Standard data given above.

Description of deutonymph. Similar to adult female with differences noted below. Body elongate (470 long), ciliated seta shorter anteriorly (7–10) than posteriorly (11–14).

Genital area: Pair of genital plates 42 long x 31 wide bearing 4 setae each. Beneath plates 2 pairs of oval acetabula present, 9–12 along longest axis, posterior acetabulum smaller than anterior. Three pairs of genital setae all nude, except 1 seta with single cilium. Anal plates narrow, 34 long. Five ciliated setae between coxae I.

Gnathosoma : Chelicerae concealed in this single specimen. Hypostome not divided into lobes, with 4 pairs of nude apical setae. Palp femur with 3 ciliated setae. Palp genu with 3 ciliated setae. Palp tibia with 5 setae, 3 dorsal nude. Base of tibial claw flanked by 2 spoon-shaped accessory setae. Palp tarsus with 3 nude apical sensory setae, 7 ciliated setae and 1 basal sensory rod.

Idiosoma: Tectum with single seta 19 long. Two parascutal setae at base of crista longer (19) than other ciliated seta. Four pairs ciliated setae anteriad sensillary area.

Leg I: Trochanter I with 3 ciliated setae. Basifemur I and telofemur I with 6 and 16 ciliated setae, respectively. Genu I distodorsally bearing pointed microgenuala (µ) 3 long, 19 ciliated setae (16 long) and 8 PT setae (13 long). Tibia I distodorsally bearing 2 R setae (10 long) with tips curved away from leg and pointed microtibiala (3 long), 9 PT setae (13 long), 5 to 6 MB setae (16–18 long) and ca. 27 ciliated setae. Tarsus I, 61 long, 25 high bearing 4 types of setae: 25 ciliated setae 21–22 long; 5 gradually-tapering nude LB setae closely parallel to tarsus (19–22 long); 11 R setae 9–10 long, with their tips directed away from tarsus; 2 SB setae, 10 long borne anterodorsally, 1 proximal and other halfway along tarsus and pointed microtarsala. No PT setae.

Leg II: Basifemur II with 3 ciliated setae, telofemur with 8 ciliated and 1 PT seta (10 long), genu II with 10 ciliated setae and 3 PT setae (10 long), tibia II with 14 ciliated setae and 2 somewhat tapering SB setae (11 long), tarsus II with ca. 22 ciliated setae, 2 SB setae and pointed microtarsalae.

Leg III: Basifemur III with 5 ciliated setae, telofemur with 7 ciliated setae, 1 PT seta (11 long), genu III with 8 ciliated setae and 3 PT setae (10 long), tibia III with ca. 14 ciliated setae and 1 PT seta (14 long), tarsus with 20 ciliated setae and 1 SB seta (11 long).

Leg IV: Coxa, trochanter, basifemur, and telofemur IV with 11, 6, 6, 9 ciliated setae respectively. Genu IV with 7 ciliated and 4 PT setae (13–14 long). Tibia IV with 10 ciliated and 3 PT setae, and 1 R seta distinguishable with tip directed away from leg. Tarsus IV with 21 ciliated setae, 1R seta (11 long) and 1 MB seta (14 long).

Standard data: ASL 47; PSL 10; PAD 23; SB 25; CTL 38; SS 19; TS 19; Sens 52; ASL/SB 1.9.

Material examined. 4 females, 3 males, 4 unfed larvae ex Eclectus roratus tree hollow nest containing 2 E. roratus eggs ( NEST 95), Australia: Iron Range, Cape York Peninsula, 12˚44’09”S, 143˚15’43”E, 22 November 1998, coll. S. Legge & R. Heinsohn; 2 females, 1 male from a second tree hollow nest, lower in the same tree, occupied by an E. roratus hen ( NEST 96), same data; 2 females, 1 deutonymph from Cacatua galerita tree hollow nest from which chicks had recently fledged ( NEST 99), same locality, 27 November 1998.

Remarks. (i) Requests have been made to all likely Australian institutions but the original type material of A. (L.) lorius has not been located. Domrow & Lester (1985) presumed that Gunther’s types would be transferred to the Australian Museum from the School of Public Health and Tropical Medicine (SPHTM). At least some of this collection was transferred to University of Queensland Insect Collection (UQIC). However, the only part of Gunther’s collection I could find at UQIC were two type slides of Schoengastia (Schoengastia) taylori Gunther. A request was also made for the types of Ascoschoengastia (L.) daria (Traub & Audy) but without success.

(ii) Thick-walled oval cells of regular shape, 5– 6 x 2–3 µm, were abundant within the unstained hysterosoma of four females, the three males and the deutonymph of A. (L.) lorius . These are assumed to be yeast-like endosymbionts (see Kroman 1979).

Figures

FIGURES 1 – 5. Ascoschoengastia (L.) lorius larva. 1, dorsal view; 2, ventral view; 3, leg I; 4, leg II, leg III. Scale bar = 100 μm.

FIGURES 6 – 9. Ascoschoengastia (L.) lorius adults. 6, female in ventral view; 7, adult in lateral view; 8, palp tarsus showing four apical setae; 9, palp tarsus lateral view showing accessory setae. Scale bars: 6, 7 = 100 µm; 8 = 1 µm, 9 = 20 µm.

FIGURES 10 – 12. Ascoschoengastia (L.) lorius adults. 10, female genital region; 11, male genital region; area sensilligera (female). Scale bars: 10, 11 = 50 µm; 12 = 100 µm.

FIGURES 13 – 18. Ascoschoengastia (L.) lorius sensory setae of adults. 13, hypostome showing nude setae and apical pores; 14, microseta from tarsus I; 15, recumbant, long solenidion (LB) and recurved seta (R) from tarsus I; 16, recurved sensory setae (R) from tarsus I; 17, short blunt (SB) solenidion from tarsus I; 18, recurved sensory seta (R), medium blunt sensory seta (MB) and microgenuala from genu I.

Tables

TABLE 1. Standard data for Ascoschoengastia (L.) lorius and A. (L.) daria larvae.

	A. daria from Borneo (Traub & Audy 1954) n= 9	A. lorius from Papua New Guinea (Domrow 1974) n= 5	A. lorius from Cape York Peninsula (this study) n=4
AW PW	48–54 65–75	41 (39–43) ± 1.6 58 (56–61) ± 2.0	38 (36–40) ± 1.8 52 (50–54) ± 1.8
SB	24–30	22 (21–22) ± 0.5	21 (18–24) ± 2.6
ASB PSB	20–26 22–26	20 (18–20) ± 1.1 22 (20–23) ± 1.1	20 (19–21) ± 0.8 19(17–20) ± 1.5
AP	24–28	21 (20–22) ± 1.2	21 (19–22) ± 1.3
AM AL	30–38 20–24	34 (32–36) ± 2.0 17 (17–18) ± 0.5	28 (25–31) ± 3.0 15 (14–16) ± 1.0
PL	33–42	35 (34–35) ± 0.6	31 (30–32) ± 0.8
Sens DS	- 33–41	36 (35–38) ± 1.2 x10–11 -	32 (30–34) ± 2.8 x10 24 (21–28) ± 2.3
VS	21	-	15–19
PW/cx 2 PW/ ASB	1.31–1.43 2.93–3.07	- 2.9	1.1–1.2 2.6 (2.5–2.7) ± 0.1
PW/AP	2.46–2.62	2.8	2.5 (2.4–2.8) ± 0.2
ASB/SB-AL	1.5–1.7	-	1.7–1.9