Simognathus fuscus Viets 1936
Creators: name: Tiago, Almir Rogério Pepato Cláudio Gonçalves
Publisher: name: Zenodo
Year: 2004
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Trombidiformes
Halacaridae
Simognathus
Simognathus fuscus

description: Simognathus fuscus Viets, 1936
(Fig. 6 –8).
Simognathus fuscus, Viets, 1936: 421 –423, figs50–54; Bartsch, 1985: 318; Bartsch, 1994:148 –151.
Material examined: All individuals were deposited in the author’s collection. Three females, on S. cymosum from intertidal rocky shore at Lázaro Beach, 23°30’S, 45°08’W, July 1991, coll. R. Curvêlo; one female, on S. cymosum from intertidal rocky shore at Lázaro Beach, 23°30’S, 45°08’W, March 1991, coll. R. Curvêlo; one female, on S. cymosum from intertidal rocky shore at Lázaro Beach, 23°30’S, 45°08’W, November 1990, coll. R. Curvêlo; one deutonymph, on S. cymosum from intertidal rocky shore at Lázaro Beach, 23°30’S, 45°08’W, July 1991, coll. R. Curvêlo; two females, on S. cymosum from intertidal rocky shore at Lázaro Beach, 23°30’S, 45°08’W, June 1992, coll. R. Curvêlo; one larva, on S. cymosum from intertidal rocky shore at Lázaro Beach, 23°30’S, 45°08’W, November 1990, Coll. R. Curvêlo; one larva, on rocky shore at Martim de Sá Beach, 23°38’ S, 45°24’W, 16 March 2001, collected during sampling activities of "Benthic marine biodiversity on the State of São Paulo" project (BIOTA /FAPESP Program); one female, on rocky shore associated algae at Martim de Sá Beach, Massaguaçu Island, 23°38’ S, 45°24’W, 16 March 2001, collected during sampling activities of "Benthic marine biodiversity on the State of São Paulo" project (BIOTA /FAPESP Program).
Description: Measurements are summarized in Table II.
TABLE II: Measurements, in m, obtained from examined individuals of Simognathus fuscus Viets, 1936.
Female Deutonymph Larva
Length Width. Length Width. Length Width.
Idiosoma 312–340 162–195 282 159 160 108
Gnathosoma 80–85 71–83 71 72 47 47
AD 146–160 91–110 118 83 71 53
PD 141–163 86–105 75 63 39 49
OC 24–33 17–22 31 17 19 13
AE 130–163 163–185 124 100 82 96
GA 126–141 91–99 27 22 ­­­ ­­­
GO 48–42 24–28 ­­­ ­­­ ­­­ ­­­ Female: Dorsal plates foveate throughout. All idiosomal plates separated by stripes of membranous cuticle. Idiosoma yellowish except posterior AD, with a brown pigmented area delimited in Fig. 6 A by a dotted line. Pair of ds­1 lies at 0.26–0.29 of AD length. Glandular pores anterior to level of ds­1, close to the plate edge. AD bearing an anterior cornea and a pair of ds­3 at 0.84–0.92 of its length.
Pair of ds­2 on the striated cuticle. OC triangle­shaped, with one large cornea. Pair of ds­4 close to anterior edge of PD, ds­5 at 0.40–0.52 of PD length. Adanal setae ventral, near posterior margin of GA.
Ventral plates foveate except anterior area of GA and close to epimeral vesicle. AE with three pairs of setae, a pair of epimeral vesicles and well­developed epimeral process on epimera I.
Distance between GO and anterior edge of GA equalling 0.40–0.43 of GA length. Next to GO there are four pairs of perigenital setae.
Segment P2 with one ventral seta and a blunt protuberance posterior to it. Palp longer than half the length of gnathosoma, P2 as long as 3.6 times the length of P3. Rostrum measures 0.21–0.24 of gnathosoma length. The anterior projection of tectum reaches beyond half of P1.
Leg chaetotaxy, observed in all individuals: leg I, 1,2,2,4,5,6; leg II, 1,2,3,4,5,6; leg III and IV, 1,1,2,3,5,5. Integument of telofemora I to IV are ornamented with large foveae. Length/height ratio from segments of leg I as follows: tarsus, 2.0–2.2; tibia 1.9–2.2; telofemur, 1.6–1.7.
Dorsal setae of telofemur III of different size; on telofemur IV they are of same length. Claw­like setae of tibia I with a proximal swelling.
Tarsus I with a heavy ventral spine, a pair of parambulacral setae and three dorsal setae. Ventral setae of tibiae II and III bipectinate, ventral setae of tibia IV nearly smooth.
Medial claw of ambulacra I stout, lateral ones slender. In remaining legs lateral claws are smooth except a dorsal accessory tooth; medial claws reduced.
Male: Unknown.
Larva: AD bearing a large anterior cornea, a pair of ds­1 and a pair of gland pores. Pairs of ds­2 to 4 lie on membranous integument. Most of ocular plates covered by a large cornea. Pair of ds­5 on PD. Adanal setae ventral, close to anal opening.
Most of anterior epimeral plate punctuated, this plate bears only two pairs of setae and a pair of epimeral vesicles on epimera II. Two conspicuous apodemes underneath membranous cuticle near AE. PE with a single ventral seta.
Five­segmented legs, chaetotaxy as follows: leg I, 1,3,4,5,6; leg II, 1,5,4,5,6 and leg III, 1,3,3,5,5.
Deutonymph: Striated cuticle broader than in females. Pairs of ds­1 and gp­1 on AD. Pairs of ds­2, ds­3 and ds­4 on membranous integument. Pair of ds­5 on anterior edge of PD. Adanal setae ventral, close to anal opening.
Medial AE punctuated, without the fovea found in female. AE with three pairs of setae and a pair of epimeral vesicles. PE with three ventral and one dorsal seta. Genital plate with one pair of setae. Chaetotaxy similar to female.
Remarks: Whereas the females analysed here are 312–340 m long, the holotype of S. fuscus is 370 m. Bartsch (1985) found in Bermudas caves one deutonymph and one larva of S. fuscus, which also are larger than the deutonymph and larva found in Brazil. However the Viets (1936) description of S. fuscus and the tabular key presented by Bartsch (1994) share most of features stated here, such as ornamentation of ventral plates, shape of dorsal ones, insertion of ventral setae on P2 distal to ventral knob and length/height ratio of the segments of leg I, which avoid having any doubt about the identification of these specimens as S. fuscus.
description: Published as part of Tiago, Almir Rogério Pepato Cláudio Gonçalves, 2004, The genera Acaromantis and Simognathus (Simognathinae, Halacaridae) on the north coast of São Paulo State, Brazil, pp. 1-16 in Zootaxa 615 on pages 11-15, DOI: 10.5281/zenodo.158730