Thalassarachna basteri ( Johnston, 1836 )

Bartsch, Ilse, 2015, Thalassarachna basteri and T. affinis (Acari, Halacaridae), history, characters, biology, and distribution, Ecologica Montenegrina 2 (3), pp. 228-241 : 230-233

publication ID	https://doi.org/ 10.37828/em.2015.2.27
persistent identifier	https://treatment.plazi.org/id/03C3214F-FFE3-FFB2-FF3D-FC1BFBF7990D
treatment provided by	Felipe
scientific name	Thalassarachna basteri ( Johnston, 1836 )
status

Treatment

Thalassarachna basteri ( Johnston, 1836)

Figures 1A–F View Figure 1 , 2A–J View Figure 2 , 3 View Figure 3 .

Acarus Basteri Johnston, 1836: 353–355 View in CoL , fig. 51a, b.

Halacarus ctenopus, Gosse 1855a: 28–29 , pl. 3, figs 1–6.

Thalassarachna Verrillii Packard, 1871: 107–109 , fig. 5a–d.

Halacarus spinifer Lohmann, 1889: 343–345 , pl. 7, figs 49, 50, 59, 73, pl. 8, figs 97, 99–105.

Halacarus (Halacarus) basteri, Lohmann 1901: 292

Agaue hirsuta, Trägårdh 1905: 63 , figs 127, 128 (non Agaue hirsuta Trouessart, 1889 , mis-identification) Halacarus (Halacarellus) basteri basteri, Viets 1927: 120 .

Halacarellus basteri var. septentrionalis Gimbel, 1938: 1–6 , figs 1–12.

Halacarus (Thalassarachna) basteri, Newell 1945: 62 .

Halacarus (Thalassarachna) basteri basteri, Newell 1947: 102–106 , figs 143–154.

Halacarellus basteri, Kirchner 1967: 345 .

Thalassarachna basteri, Straarup 1968: 264 .

Halacarus basteri basteri, Kirchner 1969: 56 .

Thalassarachna basteri, Green & MacQuitty 1987: 120 , fig. 48A–D.

non Halacarellus basteri, Makkaveeva 1966: 38–44 , figs.

Characters of adults. Idiosoma View in CoL . Length of females 864–1197 µm, of males 885–1105 µm. Dorsal and ventral plates widely separated by densely striated integument. Dorsum with four plates, AD, pair of OC and PD, and three pairs of platelets; a fourth pair of platelets covered by striated integument. Anterior dorsal plate with wide, frontal spine ( Fig. 1A, B View Figure 1 ), its width at the base about 60 µm, length 30 µm; posteromarginal part of AD with delicate pores. Pair of glp- 1 in margins of AD just anterior to the level of ds-1, glp-2 within striated marginal integument. Ocular plates 1.7–2.1 times longer than wide, with eye pigment and single cornea; posterior corner with gland pore and adjacent pore canaliculus. Posterior dorsal plate about quadrangular, slightly longer than wide, in ovigerous females (with striated integument dilated) reaching halfway between ds-4 and ds-5, in males PD slightly longer and extending to the level of ds-4 ( Fig. 1A View Figure 1 ). Pair of ds- 5 in female PD in anterior half ( Fig. 1D View Figure 1 ), in male close to middle of PD. Marginal and median part of PD with faintly reticulate ornamentation and numerous minute pores, pair of longitudinal areas evenly and very delicately punctate, without reticulation ( Fig. 1F View Figure 1 ).

Ventral plates uniformly punctate. AE with three pairs of ventral setae; PE with one dorsal and three ventral setae. Female GA slightly extending beyond large genital foramen; distance from anterior margin of GA to that of GO about 0.2 times of length of GO. GO mostly surrounded by three or four pairs of pgs, rarely five, six or even seven setae on either side of GO. Genital sclerites both anteriorly and posteriorly with two (to three) pairs of minute setae. Ovipositor extending beyond genital plate ( Fig. 1E View Figure 1 ). Male genitoanal plate larger than that of female; interval between anterior margin of GA and of GO about 0.6 of length of GO ( Fig. 1C View Figure 1 ). Genital foramen surrounded by approximately 110 perigenital setae ( Fig. 1C View Figure 1 ); genital sclerites with 8– 10 pairs of stout setae and two pairs of spurs. Female and male with three pairs of large internal genital acetabula.

Gnathosoma 1.5–1.7 times longer than wide. Tectum truncate ( Fig. 2A View Figure 2 ). Rostrum shorter than gnathosomal base, extending to end of P-2. Integument of gnathosomal base delicately punctate. Basal pair of maxillary setae at the basis of the rostrum, apical pair in posterior third. Palps almost cylindrical, P-3 with medial spine ( Fig. 2B View Figure 2 ). Three setae in basal whorl of P-4 slightly unequal in size. P-4 ending with two setulae and two spurs. Lateral surface of cheliceral basis faintly foveate ( Fig. 2D View Figure 2 ). Cheliceral claw with about 25 minute tines ( Fig. 2C View Figure 2 ).

Legs. Two anterior pairs distinctly, two posterior pairs of legs slightly shorter than idiosoma. Number of setae on leg segments variable ( Table 1). Leg I with conspicuous ventral spines; 35–70 µm long, at their basis almost 10 µm wide; telofemur I with three such spines; in general tibia I ventrally with three pairs of spines and anterior pair of setae ( Fig. 2G View Figure 2 ), rarely, as in female illustrated ( Fig. 2E, F View Figure 2 ), with four or seven spines in addition to anterior pair of slender setae. Following tibiae with bristle-like ventral setae but no spines ( Fig. 2H–J View Figure 2 ). Tarsus I with eight (rarely seven) dorsal setae, a short dorsolateral solenidion, a ventral spine, six to seven (rarely less) ventral eupathid setae, and a pair of doubled (rarely tripled) parambulacral setae. Claws on tarsus I shorter than on following tarsi; claws on tarsi II to IV with J-shaped pecten with numerous tines.

Colour. Integument almost transparent. Dorsum with three black eye spots. Gut content red-brown with dark spots ( Fig. 3 View Figure 3 ); colour highly depending on food items. In general a narrow, white bar present.

Characters of juveniles. Length of deutonymph 654–794 µm, of protonymph 452–654 µm, of larva 384– 440 µm. Outline of dorsal plates similar to plates of adults, though PD distinctly smaller. AD always with large frontal spine. Telofemora I to IV of deuto-, protonymph and larva with 2, 1, 0 spines, genua with 1, 1, 0 and tibiae with 4(–3), 2, 0 spines, respectively. Deutonymphal tarsi I to IV with 6, 6, 4(–3), 4 dorsal setae, protonymphal tarsi with 4(–3), 4, 3, 3 and larval tarsi I to III with 3, 3, 3 dorsal setae.

Kingdom	Animalia
Phylum	Arthropoda
Class	Arachnida
Order	Trombidiformes
Family	Halacaridae
Genus	Thalassarachna