Amerozercon penicillatus, 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 : 1113-1117

Amerozercon penicillatus sp. nov.

( Figures 2M, N , 8B , 9A, B )

Material examined ( Figure 3 )

Holotype: male, USA, Tennessee, Blount County, Cades Cove , 30 July 1956, leg. J.L. Bohnsack (ÉAm-013) . Paratypes: three males and one deutonymph, locality and date as for the holotype. Holotype and paratypes are deposited in HNHM .

Diagnosis of male

Anterior margin of ventrianal shield with two pairs of setae (setae Zv1 present). Dorsal setae short and plumose, with the exception of j5 and r1 which are smooth and needle-like. Third pair of opisthonotal pores (Po3) absent. Dorsal cavities uniform, with undulate anterior margin. Podonotum anteriorly covered by tile-like pattern, posteriorly bearing distinct pits, opisthonotum with large alveolar pits.

Description – male

Length of idiosoma: 258–270 µm (265 µm); width: 188–200 µm (192 µm) (n = 3).

Dorsal side ( Figure 9A ). 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). Podonotal setae short, densely plumose except r1 and j5 which are smooth and needle-like. Marginal setae of podonotum (z3, s2, r2, s3, r4, r5, s6) and j1 somewhat longer than central setae. Glands gds1 (po1) situated anteromedially to s1; gdj4 (po2) situated anteromedially to z4; gds4 (po3) on or somewhat laterally to line connecting s4 and s5, near s4. Anterior surface of podonotum covered by tiles possessing undulate posterior margins, posterior surface of the shield with distinct, alveolar pits.

Opisthonotum with 21–23 pairs of setae, J1–5, Z1–5, S1–5, marginal R-series with six to eight pairs of setae, mostly seven pairs can be observed. Each opisthonotal seta uniform, short, densely plumose. None of these setae reaching bases of the following one in the series, J-setae reaching approximately half the distance towards the insertion of the following setae. J-setae constitute nearly parallel rows, setae J5 situated on the level of dorsal cavities. Setae S2 shifted near the Z-series, situated laterally to line connecting Z1 and Z2, equidistant between these. Setae S3–5 not reaching beyond margin of the shield. Length of opisthonotal setae and distances between their insertions as in Table 6. Glands gdz6 (Po1) situated anteriorly to insertions of Z1; gdZ2 (Po2) medially to line connecting Z1 and Z2, on the level of S2; third pair of opisthonotal pores (Po3) absent; gdS5 (Po4) medially to S5. Marginal serration shallow and obtuse. Whole opisthonotal shield covered by relatively large, distinct, alveolar pits. Dorsal cavities well-developed, uniform, with undulate anterior margin.

Ventral side ( Figure 9B ). Posterolateral parts of peritrematal shields fused to ventrianal shield on level of setae R1, the separating membranous slit between ventral and dorsal shields absent. Shape of peritrematal setae typical for the genus. Peritremes straight, without dilatation near the stigma. Peritrematal shields covered by some longitudinal lines. Sternigenital shield with five pairs of setae, ornamented by arcuate lines around the genital opening, possessing irregular ditches beyond the level of setae st4. Adgenital glands gv2 with a single opening. Ventrianal chaetotaxy complete, setae Zv1 present. Postanal seta, preanal and adanal setae short, smooth and needle-like. Setae Jv5 similar to marginal setae of opisthonotum, densely plumose. 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 Jv3-Zv3-Zv4.

Gnathosoma

Situation of hypostomal and subcapitular setae typical for the family. Setae h1 elongate, needle-like. Setae h2–3 shorter than h1, 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 slender, fixed digit terminally bifurcate, with six teeth, movable digit with four teeth. Epistome ( Figure 2M ) typical for the genus Amerozercon , of Zercon - type (see Ujvári 2011b).

Description – deutonymph

Length of idiosoma: 263 µm; width: 183 µm (n = 1).

Dorsal side ( Figure 8B ). Shape and situation of dorsal setae similar to that of adults, however differences in length of setae are more expressed. On podonotum, setae j1, z3, s3, r5 and s6 significantly longer than other podonotal setae. Opisthonotal setae Z5 and S5 longer than other setae of the shield. Setae of the S-series possessing longer pili than central J- and Z-setae, hence seem to be wider. Setae J5 situated slightly beyond level of dorsal cavities. Length of opisthonotal setae and distances between their insertions as in Table 6. Position of gland poroids similar to that of adults, third pair of opisthonotal pores (Po3) absent on deutonymphs as well. Ornamentation of podonotal shield weakly developed, only a few undulate lines can be recognized as precursors of the tiles of the adults. Pattern of opisthonotum as in adults, anterior margin of dorsal cavities less sclerotized.

Gnathosoma

Each character similar to that of the adults. Similarly to A. halaskovae sp. nov., deutonymphs of A. penicillatus sp. nov. also possess characteristic, Zercon - type epistome ( Figure 2N ), similarly to adults, which is an unusual phenomenon within Zerconidae .

Female, protonymph and larva

Unknown.

Etymology

The name of the new species refers to to the brush-shaped setae (the Latin epithet “ penicillatus ” means penicillate, resembling a brush of fine hairs).

Remarks

The new species is placed in the genus Amerozercon based on the consilience of major diagnostic characters (e.g. shape of peritrematal setae, the fusion of peritrematal and ventrianal shields of male, number of R-setae). The absence of the third pair of opisthonotal pores (Po3) and the shape of marginal setae of opisthonotum also suggest that the species is related to the type-species of the genus. With respect to the general appearance of dorsal setae, the ornamentation and uniformity of dorsal cavities, the new species is most closely related to Amerozercon barbatus Ujvári, 2011 . The two species can easily be distinguished by the significantly shorter opisthonotal setae of A. penicillatus sp. nov., the shape of r1 (smooth in A. penicillatus sp. nov., barbed in A. barbatus ) and the absence of the third pair of opisthonotal pores (Po3) in A. penicillatus sp. nov. The situation of glands gds4 (po3), gdz6 (Po1) and gdZ2 (Po2) is also slightly different in the two species, but these small differences may hardly be used for distinction, until only a few specimens are known.

Key to the females of known species of Amerozercon

1. Dorsal cavities equal..................................................... 2 Dorsal cavities uneaqual................................................. 3

2. Podonotal setae j2–4, s1, z2 and z5 smooth, central surface of opisthonotum covered by small pits, dorsal cavities shallow, weakly developed.................................................... Amerozercon brevicavus Ujvári, 2011 Podonotal setae j2–4, s1, z2 and z5 plumose, central surface of opisthonotum covered by medium-sized pits, dorsal cavities well-developed........................................................ Amerozercon barbatus Ujvári, 2011

3. Lateral pair of dorsal cavities larger than the central pair.................. 4 Central pair of dorsal cavities larger than the lateral pair.................. 5

4. Lateral dorsal cavities ring-shaped, central cavities weakly developed, setae J2–3, Z3–5 and S2–5 relatively short, R-setae feathered................................................................. Amerozercon annularis sp. nov. Each dorsal cavities C-shaped, setae J2–3, Z3–5 and S2–5 elongate, R-setae pointed and barbed................... Amerozercon minimus (Sellnick, 1958)

5. Setae J2–5 smooth, Z3–5 and S3–5 elongate, central dorsal cavities five times larger than lateral cavities.................. Amerozercon auricularis sp. nov. Setae J2–5 pilose, Z3–5 and S3–5 short, central dorsal cavities two to three times larger than lateral cavities.......................................... 6

6. Third pair of opisthonotal pores (Po3) present, setae Z1–2 pilose, pilose dorsal setae bearing long pili, a pair of strongly sclerotized, arcuate ledges present behind central dorsal cavities............... Amerozercon halaskovae sp. nov. Third pair of opisthonotal pores (Po3) absent, setae Z1–2 smooth, pilose dorsal setae bearing short pili, no arcuate ledges can be observed behind central dorsal cavities.................... Amerozercon suspiciosus Halašková, 1969

Key to the males of known species of Amerozercon

1. Dorsal cavities equal..................................................... 2 Dorsal cavities uneaqual................................................. 4

2. Podonotal setae j2–4, s1, z2 and z5 smooth, central surface of opisthonotum covered by small pits................... Amerozercon brevicavus Ujvári, 2011 Podonotal setae j2–4, s1, z2 and z5 plumose, central surface of opisthonotum covered by medium-sized pits............................................ 3

3. Third pair of opisthonotal pores (Po3) present, length of J-setae 17–21 µm, setae r1 pilose........................... Amerozercon barbatus Ujvári, 2011 Third pair of opisthonotal pores (Po3) absent, length of J-setae 11–13 µm, setae r1 smooth........................... Amerozercon penicillatus sp. nov.

4. Third pair of opisthonotal pores (Po3) present, setae Z1–2 pilose, pilose dorsal setae bearing long pili, a pair of strongly sclerotized, arcuate ledges present behind central dorsal cavities............... Amerozercon halaskovae sp. nov. Third pair of opisthonotal pores (Po3) absent, setae Z1–2 smooth, pilose dorsal setae bearing short pili, no arcuate ledges can be observed behind central dorsal cavities.................... Amerozercon suspiciosus Halašková, 1969

Figures

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.

Figure 8. Dorsal view of Amerozercon deutonymphs. (A) Amerozercon halaskovae sp. nov.; (B) Amerozercon penicillatus sp. nov.

Figure 9. Amerozercon penicillatus sp. nov. male. (A) Dorsal view; (B) ventral view.