Amerozercon minimus (Sellnick, 1958) Ujvári, 2013

Ujvári, Zsolt, 2013, Amerozercon Halašková, 1969 species (Acari: Mesostigmata: Zerconidae) of the United States of America, Journal of Natural History (J. Nat. Hist.) 47 (15 - 16), pp. 1093-1120 : 1094-1099

Amerozercon minimus (Sellnick, 1958) comb. nov.

( Figures 1A, B and 2A–C )

Material examined ( Figure 3 )

USA, California, Monterey County, Big Sur area, 40 km south of Carmel , from redwood litter, 14 July 1989, leg. E.E. Lindquist (two females, deposited in CNC) , USA, California, Marin County, 0.16 km south of Samuel P. Taylor State Park , decayed redwood stump, 13 December 1958, leg. Obrien C.W. (one female, deposited in CNC) , USA, California, Mt Tamalpais , 1000 m above sea level, pine forest, mosses and lichens between rocks, 12 January 1985, leg. M. Neiger (ÉAm-089, one female, deposited in HNHM) .

Diagnosis

Anterior margin of ventrianal shield with two pairs of setae (setae Zv1 present). Many of marginal and central podonotal setae slim, distally barbed. Setae J1 and Z1–2 short, smooth, J4–5 short, distally barbed, the rest of J-, Z- and S-setae elongate, distinctly pilose on their distal half. Third pair of opisthonotal pores (Po3) absent. Dorsal cavities well-sclerotized, the lateral pair significantly larger than the central pair, the axes of the lateral pair converging posteriorly. Anterior and lateral surface of podonotum covered by tile-like pattern, posterocentral surface of podonotum and anterior surface of opisthonotum bearing net-like ornamentation with refracting dots at the connecting points, posterior surface of opisthonotum behind the level of setae J2-Z3-S4 with alveolar pits.

Description – female

Length of idiosoma: 290–323 µm (303 µm); width: 220–247 µm (236 µm) (n = 3).

Dorsal side ( Figure 1A ). Podonotum with 20 pairs of setae, j1–6, z2–6, s1–6, r2 and r4–5 inserted dorsally, r1 and r3 inserted ventrally, on peritrematal shields (see at ventral side). Setae j1–2, j4, z3–5, s3–6, r2 and r4–5 slim, pointed, distally barbed, the rest of podonotal setae smooth and needle-like. Glands gds1 (po1) situated anteromedially to s1; gdj4 (po2) situated medially to z4; gds4 (po3) laterally to line connecting s4 and s5, near s4. Anterior and lateral surface of podonotum covered by tile-like pattern, posterocentral surface of the shield bearing net-like ornamentation with refracting dots at the connecting points.

Opisthonotum with 22 pairs of setae, J1–5, Z1–5, S1–5, R1–7. Setae J1 short, smooth and needle-like, not reaching insertions of J2. J2–3 similar in appearance, elongate, distally barbed, J2 reaching bases of J3, J3 reaching insertions of J4–5. Setae J4–5 short and distally barbed. Setae J1–4 constitute parallel rows, setae J5 inserted medially to these rows, near the anterior margin of central dorsal cavities. Setae Z1–2 short, smooth and needle-like. Setae Z3–5 and S3–5 elongate, distally barbed or feathered. Z3 reaching insertions of Z4, S3–5 expanding beyond margin of opisthonotum. S4–5 expanding beyond margin of opisthonotum. Setae S2 twice as long as Z1–2, distally barbed, inserted below line connecting Z1 and S1, near Z1. Setae S1 and anterior R-setae slim, distally barbed, length of marginal setae and the number of pili on their surface decreasing posteriorly. Length of opisthonotal setae and distances between their insertions as in Table 1. Glands gdz6 (Po1) situated

(K, L) epistomes of A. halaskovae sp. nov. deutonymphs; (M) epistome of Amerozercon penicillatus sp. nov. male; (N) epistome of A. penicillatus sp. nov. deutonymph; (O) peritreme of A. suspiciosus female; (P–U) different setae of A. suspiciosus female: (P) z6; (Q) s5; (R) J1; (S) Z1; (T) S1; (U) S2; (V) peritreme of A. halaskovae sp. nov. female; (W–AB) different setae of A. halaskovae sp. nov. female: (W) z6; (X) s5; (Y) J1; (Z) Z1; (AA) S1; (AB) S2.

bases in Amerozercon minimus . anteriorly to insertions of Z1; gdZ2 (Po2) anteriorly or anterolaterally to Z2; third pair of opisthonotal pores (Po3) absent; gdS5 (Po4) anteriorly or anterolaterally to Jv5. Marginal serration shallow and obtuse. Anterior surface of opisthonotum (to level of setae J2-Z3-S4) bearing net-like ornamentation with refracting dots at the connecting points, posterior surface with small to medium sized alveolar pits. Dorsal cavities well-sclerotized and of different size. Lateral pair large, C-shaped, with axes converging posteriorly. Central cavities smaller, C-shaped, with parallel axes. Each cavity possesses slightly undulate anterior margins.

Ventral side ( Figure 1B ). Shape of peritrematal shields and peritrematal setae typical for the genus. Peritremes nearly straight or anteriorly bent, with a small dilatation near the stigma. Peritrematal shields covered by some longitudinal lines. Sternal shield well sclerotized, 59 µm long and 41 µm wide at the level of setae st2, with concave posterior margin and reticulate ornamentation. Adgenital glands gv2 with a single opening. Ventrianal chaetotaxy complete, setae Zv1 present. Postanal seta elongate and smooth, preanal and adanal setae shorter, smooth and needle-like. Setae Jv5 distally barbed. Anal valves with vestigial euanal setae. Glands gv3 situated anterolaterally to adanal setae. Anterior surface of ventrianal shield covered by squamous pattern to level of adanal setae and Jv4.

Gnathosoma

Situation of hypostomal and subcapitular setae typical for the family. Setae h1–2 similar in appearance, elongate, needle-like. Setae h3 shorter than h1–2, needle-like, h4 longer than previous setae, serrate. Corniculi horn-like, internal malae with a pair of bifurcate anterocentral branches and with serrate margins. Chelicerae relatively slen- der, fixed digit with six teeth, movable digit with four teeth. Epistome ( Figure 2A–C ) typical for the genus Amerozercon , of Zercon - type (see Ujvári 2011b).

Male and immature stages

Unknown.

Remarks

The species does not fit to the genus Zercon C. L. Koch, 1836 because of the number of marginal R-setae (six in Zercon species , seven in A. minimus ), position of glands gv3 (situated posterolaterally to adanal setae in Zercon species , anterolaterally to adanal setae in A. minimus ) and number of gland openings of gv2 (two to seven in Zercon species , one in A. minimus ). All these characters, the absence of the third pair of opisthonotal pores (Po3) and the differently shaped and sized dorsal cavities suggest that the species is closely related to Amerozercon suspiciosus Halašková, 1969 and other Amerozercon species described below. Therefore I transfer the species from Zercon to the genus Amerozercon .

Figures

Figure 1. Amerozercon minimus, female. (A) Dorsal view; (B) ventral view.

Figure 2. Different structures of Amerozercon species. (A–C) Epistomes of Amerozercon minimus females; (D, E) epistomes of Amerozercon suspiciosus females; (F) chelicera of A. suspiciosus male; (G, H) epistomes of Amerozercon annularis sp. nov. females; (I) epistome of Amerozercon auricularis sp. nov. female; (J) epistome of Amerozercon halaskovae sp. nov. female;

Figure 3. Occurrences of Amerozercon species.