Heterodispus cordidiscus, Jagersbacher-Baumann, Julia & Ebermann, Ernst, 2012

Jagersbacher-Baumann, Julia & Ebermann, Ernst, 2012, Heterodispus cordidiscus n. sp., a new soil mite from Egypt, and remarks on the nominal species H. elongatus Trägårdh, 1905 (Acari: Heterostigmatina: Scutacaridae), Zootaxa 3520, pp. 56-70 : 57-64

Heterodispus cordidiscus n. sp.

( Figs. 1–12 )

Female. Measurements of holotype: body length 232, body width (measured on the broadest part of tergite C) 168, anterior width of posterior sternal plate (measured between insertions of setae 3c) 71.

Dorsum ( Fig. 1 ) All dorsal setae barbed, c1, c2 well developed, with alveolar canal, f, e, h1, h2 thickened. Setae c1, c2 sharply pointed, d pointed, e, f, h1 and h2 blunt-ended. Average length of dorsal setae: c1 35 (n = 19), c2 38 (n = 20), d 51 (n = 19), e 43 (n = 20), f 50 (n = 20), h1 35 (n = 20), h2 37 (n = 20). Average distance between dorsal setae: c1–c1 78 (n = 20), d–d 51 (n = 20), f–f 58 (n = 20), h1–h1 26 (n = 20). Measurements of holotype: c1 32, c2 35 d 44, e 38, f 47, h1 32, h2 34; c1–c1 67, d–d 71, f–f 50, h1–h1 20. Posterior margin of tergits C, D and EF smooth or scalloped. Cupulae ia and ih roundish. Body surface finely stippled, margin of tergite C with fine, longitudinal stripes.

Venter ( Fig. 2 ) Ap1, 2 well developed, ap3 very broad, ap4, 5 weakly developed. Ventral plates finely stippled. Setae 1a, 1b, 2a, 2b barbed. 3a, 3b long, smooth, barbed, 3c thicker, barbed. 4b inserted anteriorly of 4a, both barbed. Positions of insertions of 4a and 4b may vary ( Fig. 3 ). 4c thick, barbed, straight. 2b, 3c and 4c blunt–ended, all other ventral setae sharply pointed. Pseudanal setae ps1, ps2> ps3. ps1, ps2 thickened, barbed. Average length of ventral setae (n = 20): 1a 35, 1 b 33, 2 a 33, 2 b 48, 3a 65, 3 b 61, 3 c 50, 4a 71, 4 b 77, 4 c 58. Average distance between ventral setae (n = 20): 1a–1a 20, 1b–1b 53, 2 a–2a 39, 2 b–2b 38, 3 a–3a 13, 3 b–3b 37, 3 c–3c 82, 4 a–4a 27, 4 b–4b 63, 4 c–4c 77. Measurements of holotype: 1a 37, 1 b 29, 2 a 26, 2 b 43, 3a 59, 3 b 53, 3 c 45, 4a 61, 4 b 64, 4 c 56; 1a–1a 18, 1b–1b 48, 2 a–2a 37, 2 b–2b 35, 3 a–3a 11, 3 b–3b 31, 3 c–3c 70, 4 a–4a 22, 4 b–4b 54, 4 c–4c 63.

Trichobothrium thin-stemmed, club-shaped, with fine barbs. ( Fig. 4 e).

Gnathosoma ( Fig. 5 b) roundish, average width 24 (n = 20), average length 22 (n = 13); dorsal setae ch1, ch2 and pp thin, smooth; ventral setae su thin, smooth. Each palp with setae d Ge and d Fe, 1 solenidion and accessory setigenous structure.

Legs. Leg I ( Fig. 4 a) Formula of setae: Tr1-Fe3-Ge4-TiTa16(4). Solenidia ω 1 and φ 1 finger-shaped, ω 2 and φ 2 small and thin. ω 1> φ 1> φ 2 ≥ ω 2. TiTa with well developed claw. Leg II ( Fig. 4 b) Formula of setae: Tr1-Fe3-Ge3- Ti4(1)-Ta6(1). Solenidion ω> φ, both finger-shaped, tarsal setae tc’ and pl’’ and tibial seta v’’ spine-like. Ta with two small claws and empodium. Leg III ( Fig. 4 c) Formula of setae: Tr1-Fe2-Ge2-Ti4(1)-Ta6. Solenidion φ small, fingershaped, tarsal setae tc’, pl’’, pv’ and pv’’ spine-like. Ta with two small claws and empodium. Leg IV ( Fig. 4 d) Formula of setae: Tr1-Fe2-Ge1-Ti3-Ta4. Tibial seta l’ spine-like. PrTa with empodium.

Male. Idiosoma length: 158 (134–201), n = 11.

Dorsum ( Fig. 6 ). Idiosoma with four finely stippled sclerotized plates. Most posterior plate forms dorsal cover for genital capsule. Setae v2, sc1, sc2, c1, c2, d, e, f barbed, h1 smooth, h2 minute. All setae except d blunt-ended, d pointed. Average length of dorsal setae: v2 10 (n = 11), sc1 19 (n = 11), sc2 38 (n = 11), c1 20 (n = 11), c2 35 (n = 12), d 34 (n = 11), e 18 (n = 12), f 26 (n = 12), h1 9 (n = 12). Average distance between dorsal setae: v2–v2 17 (n = 11), sc1–sc1 13 (n = 11), sc2–sc2 27 (n = 11), c1–c1 50 (n = 11), c2–c2 86 (n = 12), d–d 69 (n = 12), e–e 50 (n = 12), f–f 31 (n = 12), h1–h1 32 (n = 12), h2–h2 26 (n = 12).

Venter ( Fig. 7 ). Sternal plates finely stippled. ApI, apII clearly sclerotized. Presternal ap continuous from apI to sejugal apodeme. ApIII incomplete, apIV complete. Poststernal ap incomplete, present distally from point where apIV branch of.

Setae 1a, 1b, 2a, 2b sparsely barbed, setae 3a, 3b, 3c, 4a, 4b, 4c smooth. Average length of ventral setae: 1a 12 (n = 10), 1b 15 (n = 10), 2a 15 (n = 9), 2b 15 (n = 12), 3a 12 (n = 9), 3b 14 (n = 11), 3c 14 (n = 11), 4a 12 (n = 10), 4b 15 (n = 12), 4c 12 (n = 12). Average distance between ventral setae: 1a–1a 15 (n = 10), 1b–1b 47 (n = 10), 2a–2a 24 (n = 11), 2b–2b 42 (n = 12), 3a–3a 22 (n = 11), 3b–3b 41 (n = 11), 3c–3c 68 (n = 12), 4a–4a 17 (n = 12), 4b–4b 11 (n = 12), 4c–4c 55 (n = 12).

Gnathosoma ( Fig. 5 c) extended, tube-shaped, average length 8 (n= 10), no functional mouthparts. One pair of finger-shaped solenidia, two pairs of dorsal setae ch1 and ch2 thin, smooth, ventral pair of setae su longer, barbed. Genital apparatus ( Figs. 6 , 8 ) Length of genital capsule (tergite H and Ps) 43 (42–51), n = 10. Posterior edge of genital capsule narrowed. Surface with round, sucker-like structures with a diameter of about 2 and four ridges (two on each side) forming a heart-shaped structure. Aedeagus with diagonal stripes, internally forming a loop and continuing as ejaculatory duct into a seminal vesicle.

Legs. Leg I ( Fig. 9 a). Setal formula: Tr1-Fe3-Ge4-Ti6(2)-Ta13(2). Ta with one small claw. Solenidion ω 1 thick, long, ω 2 thinner, finger-shaped, long, φ 1 short, thin, distally thickened, φ 2 short, thin, ω 1 <ω 2> φ 1> φ 2. Leg II ( Fig. 9 b). Setal formula: Tr1-Fe3-Ge3-Ti4(1)-Ta7(1). Ta with two small claws and empodium. Solenidion ω thick, long, φ very short. Leg III ( Fig. 9 c). Setal formula: Tr1-Fe2-Ge2-Ti4(1)-Ta7. Ta with two small claws and empodium. Solenidion φ small, distally thickened. Leg IV ( Fig. 9 d). Setal formula: Tr1-Fe2-Ge1-Ti4(1)-Ta6. Distal Ta with 2 adhesive pads of differing size. Solenidion φ thin, finger-shaped, long. Tarsal setae tc’, tc” the longest, average length (n = 12) tc’ 79, tc” 49. Tarsal seta pl’’ and tibial seta v’’ thick, short, spine-like.

Larva. Idiosoma length: 171.

Dorsum ( Fig. 10 ). All dorsal setae barbed, on smooth, finely stippled dorsal shields. All setae except h2 bluntended, setae h2 pointed, situated on outgrowths. Length of dorsal setae v2 10, sc 1 25, sc 2 24, c1 18, c2 24, d 29, e 26, f 24, h1 30, h2 40. Distance between dorsal setae: v2–v2 20, sc1–sc1 20, sc2–sc2 40, c1–c1 28, d–d 44, e–e 41, f–f 24, h1–h1 15, h2–h2 13.

Venter ( Fig. 11 ). All ventral setae smooth, thin, pointed. Epimeres I with 1a and 1b, epimeres II with 2a and 2b, epimeres I and II joined; epimeres III separated, with 3a and 3b. Length of ventral setae 1a 8, 1 b 10, 2a 11, 2 b 12, 3 a 10, 3 b 10. Distance between ventral setae 1a–1a 18, 1b–1b 31, 2 a–2a 21, 2 b–2b 48, 3 a–3a 38, 3 b–3b 37.

Gnathosoma ( Fig. 5 a) roundish, width 20, length 15; two pairs of dorsal setae ch1 and ch2, ch1 short and oval, ch2 thin, smooth; one pair of ventral setae su, thin, smooth; two pairs of palpal setae, each palpus with 1 small ventral palpal solenidion and small accessory setigenous structures.

Legs. Leg I ( Fig. 12 a). Setal formula: Tr0-Fe3-Ge4-Ti6(1)-Ta11(1). Solenidia ω and φ finger-shaped, ω> φ. Ta with two small claws.

Leg II ( Fig. 12 b). Setal formula: Tr0-Fe3-Ge3-Ti4(1)-Ta7(1). Solenidia ω and φ short, thick, ω ≥ φ. Ta with two small claws and empodium. Leg III ( Fig. 12 c) Setal formula: Tr0-Fe2-Ge2-Ti4(1)-Ta7. Solenidion φ small, finger-shaped. Ta with 2 small claws and empodium.

Etymology. The species name cordidiscus (lat. cor = heart; discus = plate) refers to the distinctly heart-shaped genital capsule of the male.

Type material. Male holotype, 11 male, 57 female, and 1 larva paratypes (laboratory culture), EGYPT: Luxor, Nile riverside (2541’38.02’’N, 3237’41.18’’E), soil sample taken from sandy ground with roots; 1 January 1985, leg. E. Ebermann.

Type deposition. The type material is deposited at the following institutions:

Holotype, 10 paratypes (females), 2 paratypes (males): Zoologisches Institut und Zoologisches Museum der Universität Hamburg ZMHU, Germany (Holotype Inv.No. A35/12, paratypes A36/12);

10 paratypes (females), 2 paratypes (males): Senckenberg Museum für Naturkunde Görlitz, Germany (Collection No. 85/47331);

10 paratypes (females), 2 paratypes (males): Naturhistorisches Museum Wien, Austria (Collection No. NHMW 21855-21866);

10 paratypes (females), 2 paratypes (males): Shmalgausen Institute of Zoology Kiev, Ukraine;

16 paratypes (females), 4 paratypes (males), 1 male larva: Institute of Zoology, Karl-Franzens-University Graz, Austria.

Differential diagnosis. Heterodispus cordidiscus is separated from all other Heterodispus -species because of length differences of particular setae on the body and, most clearly, by length differences of tibial and tarsal setae on leg IV. In H. cordidiscus , the ratio of the three most peculiar tarsal setae is tc’ ~ tc’’> pv’’, while in the other species it is tc’> pv’’> tc’’. Moreover, the tibial seta d, which is comparatively short in H. cordidiscus , is pronounced in all other Egyptian species and most other Heterodispus -species. The tarsal setae on leg IV of H. paolii Mahunka, 1977 , are similar to those of H. cordidiscus , but the tibial seta d of this species is long and the dorsal setae c1, c2 and d are smooth. In the first description of H. elongatus by Trägårdh (1905), the illustration of the setae on the legs is not clear. However, H. cordidiscus is separated from this species by its longer setae c2 and by the non-existent length difference 3b> 3a which is clearly displayed in H. elongatus .

Males of H. cordidiscus do not possess piston-like appendages on the gnathosoma that can be seen in the genera Scutacarus ( Ebermann 1983, Norton and Ide 1974) and Lophodispus ( Ebermann 1982a) . Males of the genera Imparipes ( Ebermann 1982b, Delfinado & Baker 1976, Khaustov & Chydyrov 2004) and Archidispus ( Ebermann 1994) also lack such appendages.

The dorsal setae v2 and sc1 of H. cordidiscus are located close to each other and are distinctly anterior to sc2. A similar arrangement can only be seen in Lophodispus ( Ebermann 1982a) . In the genera Archidispus and Imparipes v2 is located anterior of both sc1 and sc2 ( Ebermann 1982b, 1994; Delfinado & Baker 1976; Khaustov & Chydyrov 2004) while in Scutacarus the arrangement of these setae seems to be more variable ( Ebermann 1983; Norton & Ide 1974). Since the numbers of known males are low in each genus, it cannot be stated yet whether the position of the dorsal setae indeed may be genus-specific.

The setation for legs I, II and III is the same in all known males from different genera. Differences are, however, present in leg IV. The formula Tr1-Fe2-Ge1-Ti4(1)-Ta6 that is displayed in H. cordidiscus can otherwise only be found in Lophodispus ( Ebermann 1982a) .

Figures

FIGURE 1. Heterodispus cordidiscus n. sp. female holotype, dorsal view.

FIGURE 2. Heterodispus cordidiscus n. sp. female holotype, ventral view.

FIGURE 3. Heterodispus cordidiscus n. sp. female. Examples of the variability in the positions of setae 4 a and 4 b in relation to each other; insertions of the respective specimens are connected by lines.

FIGURE 4. Heterodispus cordidiscus n. sp. female holotype. a) leg I; b) leg II; c) leg III; d) leg IV; e) lateral part of prodorsum.

FIGURE 5. Heterodispus cordidiscus n. sp. a) gnathosoma of male larva, dorsal view; b) gnathosoma of female, ventral view; c)

FIGURE 6. Heterodispus cordidiscus n. sp. male, dorsal view. ae = aedeagus, dej = ejaculatory duct, sv = seminar vesicle.

FIGURE 7. Heterodispus cordidiscus n. sp. male, ventral view. gn = gnathosoma.

FIGURE 8. Heterodispus cordidiscus n. sp. male, lateral view of the genital apparatus. ae = aedeagus, dej = ejaculatory duct, lo = internal loop of the aedeagus, sv = seminar vesicle.

FIGURE 9. Heterodispus cordidiscus n. sp. male. a) leg I; b) leg II; c) leg III; d) leg IV.

FIGURE 10. Heterodispus cordidiscus n. sp. male larva, dorsal view.

FIGURE 11. Heterodispus cordidiscus n. sp. male larva, ventral view. The posterior setae ps are covered with particles. gn = gnathosoma.

FIGURE 12. Heterodispus cordidiscus n. sp. male larva. a) legI; b) leg II; c) leg III.