Scaptognathus gibbosus Bartsch, 1977

Pepato, Almir R., Tiago, Cláudio G. & Rocha, Carlos E. F., 2011, Psammophilous halacarid mites (Trombidiformes, Halacaridae) from the North Coast of São Paulo State, Brazil, Zootaxa 2823, pp. 47-60 : 50-52

Scaptognathus gibbosus Bartsch, 1977

( Fig. 3 )

Scaptognathus gibbosus Bartsch, 1977: 82 , fig. 343–356; Morselli & Mari 1986: 147, Fig. G–I

Material examined. 1 female (MZSP-AC73), 1 male (MZSP-AC74), and 2 males (Pepato´s collection), 37–45 cm, São Francisco Beach, 27 May 2002. All mites collected by researchers of BIOTA /FAPESP Program. Description. Measurements summarized in Table 2.

Female Male

Length Width Length Width Idiosoma 175 95 155–163 93–94 Gnathosoma 137 60 124–135 57–58 AD 60 70 57–60 61–67 PD 85 62 80–84 60–65 OC 20 --- 19–21 10–12 AE 41 94 38–40 91–94 GA 58 42 55–58 46–54 GO 22 20 19–20 12– 13 Female.AD and PD with shallow depressions surrounded by canaliculi. Such depressions more elongated and irregular in shape on AD than on PD ( Fig. 3 A). Ocular plates smooth.

Pair of ds-1 much longer than other dorsal setae. Pairs of ds-2, ds-3 and ds-4 on membranous cuticle. Pairs of ds-5 and ds-6 on PD. Adanal setae on anal papillae.

Ventral plates smooth. Pars membranosum composed by parallel bars, 29 long, 30 wide. Two pairs of perigenital setae on GA.

Gnathosoma with coarse reticulum of panels surrounded by canaliculi dorsally. Gnathosoma ventrally covered by broad and shallow depressions at muscular insertion sites, foveate on each side of pharynx. Gnathosoma 0.78 of idiosomal length. Rostrum 56 long, 14 wide at level of tritorostral setae, 29 wide at apical swelling. Four-segmented palp: P1 without setae; P2 with 2 dorsal setae; P3 with medial broad scythe-shaped spine; P4 with 2 slender setae, 1 spine, 2 apical spurs and 1 short seta.

Leg chaetotaxy, bipectinate setae indicated by Roman numerals: Leg I, 0,2,2,5(II), 6(III),4(I); Leg II, 0,1,2,4,5(II),3; Leg III, 1,2,1,2,5(II),3; Leg IV, 1,1,1,2,5(II),3. Tarsus I with ventral bipectinate seta, solenidion, famulus and 1 pair of singlet eupathidia. All tarsi with slender and smooth lateral claws and medial reduced claw.

Male. Similar to female except for genital area. Gnathosoma 0.76–0.83 of length of idiosoma. Pars membranosum small, 5–7 long, 9–11 wide. If PM taken into account, spermathophore and GO apart from anterior edge of GA by 11–14 and 27–28, respectively. On GA 12–13 pairs of pgs. On genital sclerites 2 pairs of sgs.

Remarks. The original description of Scaptognathus gibbosus was based on the material from the Galapagos Archipelago ( Bartsch 1977). Morselli and Mari (1986) obtained this species from samples taken at Sar Uanle, Somalia. Brazilian specimens fit the original description, although they have two setae on P2 as Somalian material. The authors, following Morselli and Mari (1986), regard the absence of basal setae on P 2 in the Bartsch’s original description as a slight oversight. Telofemur of leg III of Brazilian material has a single dorsal seta while some Galapagos individuals display two setae on that segment, which is regarded to reflect intraspecific variation.

Figures

FIGURE 3. Scaptognatus gibbosus Bartsch, 1977: A, dorsum of idiosoma, female; B, venter of idiosoma, female; C, dorsum of gnathosoma, female; D, leg IV of male in lateral view; E, leg I of female in medial view; F, venter of gnathosoma, female; G, genitoanal plate of male; H, leg III of male in medial view. I, leg II of male in lateral view. Scale bars = 25 µm.