Halacarus todaroi, Pepato, Almir R. & Silveira, Paulo Sergio Amorim Da, 2013

Pepato, Almir R. & Silveira, Paulo Sergio Amorim Da, 2013, Two new species of Halacarus (Acari, Prostigmata) from Brazil, Zootaxa 3670 (4), pp. 591-600 : 597-599

Halacarus todaroi sp. nov.

( Figs. 3–4 )

Holotype: Female (UFMG-AC1200178), from shell debris at a depth of 8 m near Itassucê Islet, Barequeçaba Beach (23º 50' S, 45º 27' W), 19 March 2007, coll. A. Todaro.

Paratype: Male (UFMG-AC1200177), from shell debris at a depth of 8 m near Itassucê Islet, Barequeçaba Beach (23º 50' S, 45º 27' W), 25 August 2008, coll. A. Pepato.

Description. Female: Idiosoma length 502, width 236. AD length 190, including the anterior triangular spine 34 μm long, width 207, with reticulate surface ( Fig. 4 B). Ds-1 on AD, at level 0.60 of AD, posterior to gp-1. Gp-1 at level 0.45 of AD.

OC length 17, width 10, lacking corneae ( Fig. 4 B). Ds-2 to ds-5 on membranous cuticle. Gp-2 ventrally displaced, at level 0.38 of idiosoma length. Pore canaliculus on posterior corner of OC. Gp-3 at level 0.45 of idiosoma length. Gp-4 at level 0.72 of idiosoma. PD length 138, width 97. Adanal setae on the rear of PD, at same level as gp-5.

AE length 105, width 226, with three pairs of setae and without epimeral pores. PE with three ventral setae and one dorsal seta.

Anterior pair of pgs placed on GA, apart from anterior edge of GO by 28. GA length 95, width 107. GO length 54, width 35, 41 μm from anterior edge of GA. A single pair of pgs close to GO on GA. Three pairs of sgs on genital sclerites, grouped 1:2.

Gnathosoma length 130, width 77. Rostrum length 66, equal to 0.51 of gnathosoma length. Trito- and basirostral setae on rostrum ( Fig. 3 C).

Legs with striated cuticle ( Fig. 4 A). Leg chaetotaxy as follows: Leg I, 1, 2, 8 (2S), 11 (2S), 13 (4S), 5 (2S); leg II, 1, 4, 6, 8 (1S), 10 (2S, 1B), 5; leg III, 2, 2, 4, 5, 8, 3; leg IV, 1, 2, 4, 5, 8, 3. Tarsus I with three dorsal and two ventral setae, three pairs of eupathidia as parambulacral setae, and setiform famulus and solenidion. Tarsus II with three dorsal and two ventral setae, two pairs of eupathidia and a setiform solenidion. Tarsi III-IV with a pair of parambulacral setae and three dorsal setae, without ventral setae. Length of telofemora, genua and tibiae of leg I, 122 μm, 111 μm, and 93 μm, respectively.

Lateral claws without pecten, with a narrow accessory process. Median claw bidentate.

Male: Idiosoma length 462, width 216; AD, length 172, width 111; OC length 16, width 8; PD length 103, width 100. Similar to female in most features, except for the characteristics of the genital area and plumose parambulacral setae on tarsus IV in the male.

GA length 121, width 102. GO length 33, width 30, 70 μm from anterior margin of GA. 54 perigenital setae surrounding GO. Two pairs of distinct outlying setae beside GO. Subgenital setae on genital sclerites, grouped 2:2. Spermatophorotype extending 18 μm beyond GO ( Fig. 3 E).

Etymology. The name is dedicated to Dr. Antonio Todaro, who gave one of the individuals to the first author, and for his relevant contributions to the knowledge of meiofauna.

Remarks. Halacarus todaroi sp. nov. can be distinguished from congeners by the following set of characteristics: Absence of conspicuous sexual dimorphism concerning the extension of PD, which does not bear gp- 4 in either sex; corneae and gp-3 lacking on OC, although this plate is present and bears a pore canaliculus at its posterior corner; absence of a platelet posterior to OC or on PD, no pgs anterior to GA in neither female nor male; leg epicuticle striated. Some of the characteristics listed above are unclear from the original description of Halacarus validus by Gimbel (1919) and the re-description by Newell (1984). However, H. validus clearly differs from the species described here in the narrow AD posterior to gp-1, and ds-1 and gp-1 aligned. In H. todaroi sp. nov., AD is broader on its posterior portion, and ds-1 is posterior to gp-1. Other species that share some features with this new species are Halacarus bisulcus Viets, 1927 and Halacarus propiquus ( Viets, 1940) . Halacarus propiquus , however, is discernible from the new species by the presence of ventral setae on tarsi III and IV, and epicuticle on femora most likely punctuate instead of striated ( Newell, 1984); Halacarus bisulcus is also distinct from H. todaroi sp. nov. in the presence of combs on lateral claws of tarsi II and III, and pgs ordered in a single ring around GO and three to four pairs of outlying setae in the male ( Green & Macquitty, 1987; Bartsch, 1980; Monniot, 1962), totaling 43 pgs according to Bartsch (1980, fig.19) instead of two pairs of outlying setae and 58 pgs ordered in two rings in H. todaroi sp. nov.

Figures

FIGURE 3. Halacarus todaroi sp. nov., Female: A. Idiosoma, dorsal view. B. Idiosoma, ventral view. C. Gnathosoma, ventral view. D. GA. G, H and I. Legs II, III and IV, respectively; J. Tarsus I; Male, E. GA; F. Leg I. K. Tarsus IV. Scale bars: A, B: 100 μm. C, D and E: 30 μm. F – H and I: 50 μm. J and K: 10 μm.

FIGURE 4. Halacarus todaroi sp. nov., Female: A. Leg II telofemur. Note the cuticle striation. B. Anterior right portion of idiosoma. Note the cuticle reticulation on AD and the lacking of corneae on OC. Scale bars: 20 μm.