Actacarus arabius, Bartsch, Ilse, 2004

Bartsch, Ilse, 2004, Psammophilous halacarid mites from Kuwait: Description of species of the genera Actacarus and Scaptognathides (Acari: Halacaridae), Zootaxa 755, pp. 1-8 : 2-5

Actacarus arabius spec. nov.

Figs 1–16

Material examined

Holotype male, BMNH, Southern Kuwait, Al­Zoor, at the Texaco Beach Club, 28°44'30.7"N 48°22'40.8"E, upper to mid littoral, coarse sand, June 2002, coll. T. Ferrero. Paratypes on slides: Three males, BMNH, collecting data same as above; one female, BMNH, collecting data same as above; one deutonymph, BMNH, collecting data same as above; one protonymph, BMNH, collecting data same as above; one male, SMF, collecting data same as above; one male, one female, ZMH, collecting data same as above. Paratypes in ethanol: one female, two males, two protonymphs, BMNH.

Diagnosis

Length 167–195 µm. Surface of dorsal plates punctate and delicately foveate. Anterior margin of idiosoma truncate. Opposing margins of AD and PD almost truncate. Length relation AD:PD equalling 1: 2.4. OC small. Opposing margins of AE and GA almost truncate. AE and PE each with three pairs of setae. Ovipositor almost extending to anterior pair of pgs. Male GA with pair of outlying setae at 0.3 and 11 pairs of pgs lateral and posterior to small GO. Male genital sclerites with two pairs of sgs. Tectum arched. Tibia I with four dorsal and two ventral setae. Tibiae III and IV with two slender ventral setae. Tarsi III and IV with four and three dorsal setae, respectively.

Description ( Fig. 3 ). Foveae elongate, about 1 µm in length. Anterior margin truncate. Length of AD 53 µm, width 66 µm; posterior margin almost truncate ( Fig. 1 ). Pair of gland pores level with insertion of leg I. Length of OC 12 µm; with gland pore and pore canaliculus (cf. Fig. 15 ). Length of PD 130 µm, width 83 µm. Anterior margin wide and truncate; with two pairs of gland pores; anterior pair slightly posterior to the level of insertion of leg IV. Dorsal setae delicate; ds­1 situated on AD slightly posterior to the level of gland pores; ds­2 within striated integument; ds­3 to ds­6 on PD as illustrated ( Fig. 1 ); ds­ 6 in posterior margin of PD.

Surface of ventral plates delicately pitted. Length of AE 85 µm, width 87 µm; with three pairs of setae. Posterior margin of AE truncate and extending backward far beyond posterior pair of setae ( Fig. 2 ). Length of PE 98 µm, extending beyond insertion of leg IV; PE with one dorsal and three ventral setae. Length of GA 80 µm, width 58 µm. Anterior margin of GA somewhat concave. Small GO at edge of genital groove, its width 13 µm, distance to anterior margin of GA equalling 2.9 times distance from GO to base of anal plate. Pair of outlying setae at about 0.3 relative to length of the plate. Eleven pairs of perigenital setae lateral and posterior to GO. Each genital sclerite with two minute sgs ( Fig. 4 ). Spermatopositor large ( Fig. 5 ); Fig. 4 showing only central portion of spermatopositor.

Gnathosoma: Length 62 µm, width 42 µm. Integument of gnathosomal base evenly punctate. Tectum arched ( Fig. 7 ). Rostrum triangular, rather slender and almost as long as gnathosomal base. Palps slightly flattened ( Fig. 6 ).

Legs: Slender. Leg I longer than following legs. Tibiae slightly longer than telofemora. Leg chaetotaxy (with solenidion and pas included): leg I, 1, 2, 3, 5, 5, 9; leg II, 1, 2, 3, 3, 5, 5; leg III, 1, 2, 2, 3, 5, 6; leg IV, 1, 2, 2, 3, 5, 5. Tibiae I to IV each with three dorsal and two ventral setae ( Figs 8–11 ); ventral setae slender and smooth, almost equal in length. Lateral fossa membrane large on tarsus I but small on following tarsi. Tarsus I with three dorsal setae and solenidion ( Fig. 12 ); dorsolateral fossary seta blunt, dorsomedial seta tapering. Tarsus II with claviform solenidion ( Fig. 13 ). Tarsi III ( Fig. 14 ) and IV with four and three dorsal setae, respectively. Tarsi I to IV with pair of setiform pas.

Claws of leg I apparently smooth. Claws of tarsi II to IV with pectines and coarse tines.

Female

Length 187 µm. Dorsal aspect same as in male. Length of AE 86 µm, that of GA 74 µm. GA with three pairs of pgs, the posterior pair concealed by genital sclerites. Ovipositor extending beyond GO but not reaching to the level of first pair of pgs ( Fig. 16 ).

Juveniles

Length of deutonymphal idiosoma 183 µm, length of gnathosoma 52 µm. Length of protonymphal idiosoma 142 µm, length of gnathosoma 47 µm. Dorsal and ventral plates smaller than in adults.

Remarks

Actacarus arabius shares several characters with A. clipeolatus Morselli and Mari , a species recorded from the Indian Ocean, from a beach at Sar Uanle, Somalia ( Morselli & Mari 1986). The dorsal plates of the two species are foveate and punctate, size and chaetotaxy of their legs are similar. Compared to A. clipeolatus , the ornamentation of the dorsal plates of A. arabius is more delicate, the AD is distinctly wider than long, platelets between the PD and PE are lacking, the ovipositor is shorter relative to the length of GA, the male GO is in the posterior half of GA and most of the pgs are lateral to the GO.

When summarizing the geographical distribution of Actacarus, Bartsch (1999) distinguished between three species groups which were mainly characterized by a combination of number of setae of tarsi III and IV and shape and arrangement of setae of tibiae III and IV. The character combination in A. arabius — tarsi III and IV with four and three dorsal setae, ventral setae of tibiae III and IV paired and similar­sized — is shared with A. australis Bartsch , A. bacescui Konnerth­Ionescu , A. cornutus Otto , A. illustrans Newell , A. karoensis Abé , and A. sinensis Bartsch (Bartsch 1999; Otto 2000). Further features in common are: opposing margins of AD and PD wide, almost truncate, and AE and PE with three pairs of ventral setae. Distinguishing characters are: the tectum of A. bacescui and A. cornutus bears a small spine, whereas that of A. arabius is arched; in A. karoensis there is a series of small platelets lateral to the AD and PD, these platelets are lacking in A. arabius ; tibia I of A. australis , A. illustrans and A. sinensis bears seven setae, that of A. arabius five setae.

Figures

FIGURES 1 ­ 11. Actacarus arabius spec. nov., male. 1, idiosoma, dorsal; 2, idiosoma, ventral; 3, part of AD and PD with foveae; 4, posterior GA; 5, genitoanal plate; 6, gnathosoma, lateral; 7, gnathosoma, ventral; 8, leg I, medial; 9, leg II, medial; 10, leg III, medial; 11, leg IV, medial. Scale line = 50 µm. (1 – 4, 6 – 11, holotype; 5, paratype)

FIGURES 12 – 16. Actacarus arabius spec. nov. 12, tarsus I, lateral, male; 13, tarsus II, lateral (medial setae and medial claw in broken line), male; 14, tarsus III, medial (lateral setae and claw omitted), female; 15, idiosoma, marginal, female; 16, idiosoma, ventral, female. Scale line = 50 µm. (12, 13, holotype; 14 – 16, paratype)