Simognathus leiomerus Trouessart 1894
Creators: name: Durucan, Furkan
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Trombidiformes
Halacaridae
Simognathus
Simognathus leiomerus

description: Simognathus leiomerus Trouessart, 1894
Figures 7A–I; 8A–I; 9A–H; 10A–D; Table 4
[Simognathus andrei Monniot, 1961: 585–590; Figs. 1A–C, 2A–D, 3A, B
Simognathus leiomerus Bartsch, 1980: 43, 44, Figs. 23–31]
Material examined. All individuals slide mounted, collected at St. 4 (ErenkuŞ, Antalya), fine sand, 5–6 m, 36.865497, 30.724024, 16 June 2021. Female (FDHAL-24/113), dissected, Female and deutonymph (FDHAL-24/114), dissected, Three females (FDHAL-24/115, FDHAL-24/116, FDHAL-24/117), undissected, Three males (FDHAL-24/118, FDHAL-24/119, FDHAL-24/120), undissected, Deutonymph (FDHAL-24/121), undissected, Protonymph (FDHAL-24/122), undissected.
Redescription. Measurements presented in Table 4
Morphology and notes. Females. Dorsal and ventral plates well developed and covered by foveae (Fig. 7A, B; 9A, B). Integument brown coloured (Fig. 9A–H) deeper integumental layers with numerous, very delicate canaliculi. Dorsum has six pairs of setae, ds-1 and ds-3 on AD. Ds-2 on anterior end of OC, reduced to a small oblong subcuticular platelet (Fig. 10C). Pairs of ds-4 to ds-6 on PD. Marginal and median AE foveated and with three pairs of setae and a pair of epimeral vesicles which are large and 37 long. PE with a dorsal and three ventral setae. Anterior part of GA truncate. Interval from GO to anterior margin of GA equalling 0.6 times the GO’s length. GA with 4 pairs of pgs but no sgs (Fig. 7 B'). Gnathosomal base almost globular, with three segmented palps (Figs. 7D, E; 10B). Second palpal segment with a ventral seta inserted in ventral knob. Tectum triangular. Leg chaetotaxy, from trochanters to tarsus (bipectinated setae between parentheses; solenidia and famulus excluded, pas included) (Figs. 7F–I); Leg I: 1, 2, 1, 4, 5, 6; Leg II: 1, 2, 2, 4, 5(2), 6; Leg III, 1, 1, 3, 3, 5(2), 6; Leg IV, 1, 1, 2, 3, 5(2), 6. Tarsus I with 3 dorsal setae, dorsolateral solenidion, and a strong spiniform ventral seta and a pair of pas apically. Tarsus I paired claws and pair of long pas. Ventral seta on tibia I tapering; ventromedial seta smooth. Tarsus II with one ventral seta and pair of pas. Paired claws of tarsi II to IV each with accessory process; tarsi II and III with pecten but tarsi IV has no pecten. Lateral claws on Tarsi I and IV smooth, on tarsi II–III with combs of well-developed tines.
Males. Male is similar to female except for the genital plate (Fig. 7C). GO surrounded by 18 pgs. Spermatopositor 62 long, extending slightly beyond the ring of pgs. Three pairs of sgs are present (Fig. 7C ').
Deutonymphs. Dorsal and ventral plates covered by foveate but the plates less developed than adults (Figs. 8H, I; 9E, F). Pair of ds-1 on AD. OC reduced to small oblong subcuticular platelet. Pairs of ds-2, ds-3 and ds- 4 in membraneous integument. Ds-5 and ds-6 on PD. AE with two pairs of setae. PE with one dorsal and two ventral setae. GP with a single pair of pgs (Fig. 8 I’). Leg chaetotaxy similar to female.
Protonymph. Dorsal and ventral plates covered by foveate but the plates less developed than adults (Figs. 8A–C; 9G, H). Pair of ds-1 on AD. OC reduced to small oblong subcuticular platelet. Pairs of ds-2, ds-3 and ds- 4 in membraneous integument (Fig. 8A '). Ds-5 and ds-6 on PD. AE with two pairs of setae. PE with one dorsal and two ventral setae. GP much smaller than in female. No setae on genital plate (Fig. 8B '). Leg chaetotaxy, from trochanter to tarsus (solenidia and famulus excluded, pas included) (Figs. 8D–G); Leg I: 1, 1, 1, 4, 4, 4; Leg II: 1, 1, 2, 3, 4, 4–5; Leg III, 1, 1, 2, 3, 4, 5; Leg IV, 0, 2, 3, 4, 4. No pecten on claws.
Remarks. This species was described by Trouessart, 1894 from Granville (French Atlantic). Later, the species was reported from Roscoff (French Atlantic) from 7 m depths by Bartsch (1980). Afterwards, the species was found among amphioxus sand habitat (5 m depth) from French Mediterranean by Monniot (1961). With regard to the external morphological characters, our specimens correspond to specimens from Bay of Morlaix (France Atlantic) (Monniot 1961; Bartsch 1980). This is the first report of the species from Türkiye. The species belongs to leiomerus group. This species group may be recognised by lacking corneae, OC reduced, completely or to an elongate sclerite (Bartsch 1994) and additionally S. leiomerus may recognised by: (1) body uniformly coloured, (2) marginal and median AE foveate, (3) AE separated from GA both female and male, (4) no outlying setae in males.
description: Published as part of Durucan, Furkan, 2025, Contributions to the knowledge of the subfamily Simognathinae (Acari: Halacaridae) of Türkiye, pp. 151-168 in Zootaxa 5570 (1) on pages 161-164, DOI: 10.11646/zootaxa.5570.1.7, http://zenodo.org/record/14734721