Stigmaeus exilis, Doğan & Doğan, 2021

Doğan, Salih & Doğan, Sibel, 2021, Stigmaeus exilis, a new fusiform species of Stigmaeus Koch (Acariformes: Stigmaeidae) from Sansa, Turkey, Persian Journal of Acarology 10 (1), pp. 19-28 : 20-26

Stigmaeus exilis sp. nov. ( Figs. 1–7 )

http://zoobank.org/ urn:lsid:zoobank.org:act:63B28B22-3D51-4C78-A88A-8B2D3BC18216

Description (female, n = 3)

Body fusiform ( Figs. 1 , 4 ); length of body 442 (403–426), width 162 (137–154).

Dorsum ( Figs. 1A , 4A , 5–7A ) – Anterior margin of prodorsum microtuberculate, other parts of integument striated except shields. Propodosomal shield with an apodemal marking centrally and bearing three pairs of setae (vi, ve and sci). Posterior margin of propodosomal shield indenting forward and dual striated. Eyes and postocular bodies absent. Auxiliary shields not ornamented and bearing setae sce. Central shield with two pairs of setae (c 1 and d 1). Median zonal shield entire, elongated between intercalary shields and bearing setae e 1. Marginal shields elongate, nearly as long as central shield and bearing setae d 2. Lateral zonal shields elongate, nearly extend to suranal shield and bearing setae e 2. Intercalary shields divided, with setae f 1. Suranal shield entire, with three pairs of setae (h 1–3). Propodosomal and central shields punctated and faintly reticulated in the middle, other dorsal shields punctated but without reticulations. Dimensions of setae as follows: vi 24 (20–21), ve 67 (56–61), sci 28 (24–25), sce 40 (34–36), c 1 19 (15–16), c 2 56 (48–49), d 1 18 (13– 14), d 2 18 (17–18), e 1 17 (15–16), e 2 21 (17–18), f 1 46 (41–44), h 1 28 (26–27), h 2 37 (32–33), h 3 25 (21–23). Distances between setae: vi–vi 17 (15–16), ve–ve 22 (22–24), vi–ve 25 (19–22), sci–sci 35 (32–33), ve–sci 67 (56–64), sci–sce 43 (37–42), sce–sce 110 (96–108), c 1 – c 1 17 (17–18), d 1 – d 1 17 (16–17), d 2 – d 2 93 (85–86), c 1 – d 1 64 (55–56), c 1 – d 2 48 (42–48), d 1 – d 2 46 (37–41), e 1 – e 1 29 (25–28), d 1 – e 1 45 (46–48), d 1 – e 2 62 (57–65), e 2 – e 2 93 (78–86), e 1 – e 2 33 (21–27), e 2 – d 2 83 (77–78), f 1 – f 1 44 (39–41), e 1 – f 1 41 (37–38), e 2 – f 1 44 (35–37), h 1 – h 1 26 (20–22), h 2 – h 2 56 (48–49), h 1 – h 2 11 (11–12), h 3 – h 3 69 (65–69). Setae ve and c 2 smooth, others faintly barbed.

Venter ( Figs. 1B , 4B , 7B, C ) – Setae c 2 placed on humeral shields. Coxisternal shields separated, bearing three pairs of setae (1 a, 3 a and 4 a). Aggenital shield entire and with four pairs of setae (ag 1–4). Genital shields bearing three pairs of setae (g 1–3). Pseudanal shields bearing three pairs of setae (ps 1–3). Humeral, coxisternal and aggenital shields punctated. Area between propodosoma and hysterosoma microtuberculate as in anterior margin of prodorsum. Dimensions and distances of ventral setae as follows: 1 a 18 (13–16), 3 a 18 (16–17), 4 a 13 (9–12), 1 a –1 a 20 (15–16), 3 a –3 a 30 (24–28), 4 a –4 a 28 (20–23), ag 1 11 (11–12), ag 2 13 (13–14), ag 3 19 (16–18), ag 4 23 (19–20), g 1 6 (6–7), g 2 8 (9–12), g 3 14 (13–17), ps 1 30 (33–34), ps 2 26 (26–27), ps 3 9 (10–11).

Legs ( Fig. 3 ) – Leg segments punctated. Leg I 154 (145–147), leg II 118 (109–111), leg III 112 (107–108), leg IV 133 (131–132). Chaetotaxy of leg segments as follows: coxae 2–2–2–2, trochanters 1–1–2–1, femora 6–4–3–2, genua 5(+1κ)–5–3–3, tibiae 5(+1  +1 )–5(+1 )–5(+1 ) –5(+1 ), tarsi 13(+1ω)–9(+1ω)–7(+1ω)–7(+1ω). Leg supracoxal setae (elcp) pudgy. Solenidion κ on genu I setiform. All tarsi with solenidion ω.

Gnathosoma ( Figs. 1 , 2 , 5 ) – Subcapitulum 78 (72–73) long and punctated, with two pairs of adoral setae (ro 1, 2) and two pairs of subcapitular setae (m and n), dimensions and distances between setae, m 11 (10–12), n 17 (16–17), m–m 13 (12–13), n–n 26 (22–24), m–n 14 (13–14). Chelicerae punctated, 89 (81–83) long. Palp punctated, 79 (74–75) long. Numbers of setae and solenidia from palpfemur to palptarsus: 3, 2, 2 + 1 claw + 1 accessory claw, 4 + 1 solenidion ω + 1 tridentate

eupathidium. Palp supracoxal setae (elcp) pudgy.

Male and immature stages Unknown.

Etymology

The specific name “ exilis ” is a Latin adjective, means thin, slim or slender, referring to the thin and slender body.

Type material

Holotype: ♀, Paratypes: 2♀♀, from soil in a dead walnut tree hollow, Sansa Gorge – TURKEY, 39° 33' 58.6'' N, 40° 06' 31.3'' E, 1477 m a.s.l., 11 May 2020; leg. Salih Doğan.

Remarks

Stigmaeus exilis sp. nov. closely resembles Stigmaeus gracilimus Summers in that having thin and slender body and entire median zonal shield; however, it differs from the latter by: the presence of reticulate patterns on the propodosomal shield, posterior margin of the propodosomal shield indenting forward by striae and four setae on femur II. In S. gracilimus there is no reticulations on propodosomal shield, posterior margin of propodosomal shield is smooth and femur II bears five setae ( Summers 1962). In addition, idiosoma of the new species is longer than that of S. gracilimus : length of body 442 (403–426) in the new species whereas 296 in the latter ( Summers 1962).

Stigmaeus exilis sp. nov. is also similar to Stigmaeus amasyanus Dönel, Doğan, Sevsay & Bal. However , the new species can be easily distinguished from the latter in that marginal and lateral zonal shields of the new species are longer than those of S. amasyanus . Marginal shields elongate, nearly as long as central shield in the new species whereas relatively short in S. amasyanus ; lateral zonal shields elongate, nearly extend to suranal shield in the new species whereas very small and no extend to suranal shield in the latter. Extra distinctive characters for more easily separating these two species can also be mentioned. Distance between d 1 – d 1 17 (16–17) in the new species whereas 30 (35) in S. amasyanus ; d 1 – d 1 <e 1 – e 1 in the new species whereas d 1 – d 1 ≈ e 1 – e 1 in the latter. In addition, dorsal shields punctated in the new species versus no dorsal punctations in the latter ( Dönel et al. 2012).

Moreover, Stigmaeus exilis sp. nov. can be thought to be closely related to Stigmaeus indivisus Doğan in bearing a single median zonal shield. It can be separated from S. indivisus by: marginal and lateral zonal shields present whereas absent in S. indivisus , four setae on femur II versus six setae in S. indivisus , aggenital shield entire but divided in S. indivisus ( Doğan 2019a) .

Figures

Figure 1. Illustrations of Stigmaeus exilis sp. nov. (Holotype female) – A. Dorsum of body; B. Venter of body; C. Setae vi and d1.

Figure 2. Illustrations of Stigmaeus exilis sp. nov. (Holotype female) – A. Chelicerae; B. Palp.

Figure 3. Illustrations of Stigmaeus exilis sp. nov. (Holotype female) – A. Leg I; B. Leg II; C. Leg III; D. Leg IV.

Figure 4. Microscopic images of Stigmaeus exilis sp. nov. (Holotype female) – A. Dorsum of body; B. Venter of body.

Figure 5. Microscopic image of Stigmaeus exilis sp. nov. (Paratype female) – Anterior of idiosoma and chelicerae.

Figures 6. Microscopic image of Stigmaeus exilis sp. nov. (paratype female) – A. Prodorsum; B. Central and marginal shields.

Figure 7. Microscopic image of Stigmaeus exilis sp. nov. (paratype female) – A. Median zonal, lateral zonal, intercalary and suranal shields; B. Coxisternal and humeral shields; C. Aggenital, genital and anal shields.