Trouessartia helmitheros Mironov and Chandler, 2020

Mironov, Sergey V. & Chandler, C. Ray, 2020, Feather mites of the genus Trouessartia (Acariformes: Trouessartiidae) from passerines (Aves: Passeriformes) in Georgia, USA, Zootaxa 4860 (1), pp. 1-54 : 27-30

Trouessartia helmitheros Mironov and Chandler sp. n.

( Figs. 17–19 )

Type material. Holotype male ( BMOC 20-0303 - 013 ), 16 male and 20 female paratypes from Helmitheros vermivorum (Gmelin, JF, 1789) ( Passeriformes : Parulidae ), ( SVM 20-0217 - 9 ), USA, Georgia, Georgia Southern University Campus , 32°25’15”N, 81°47’22”W, 3 October 2013, coll. C. R. Chandler.

Depositories. Holotype, 8 male and 10 female paratypes— UMMZ, remaining paratypes—ZISP.

Description. MALE (holotype, ranges for 10 paratypes in parentheses) ( Figs. 17 , 19 A–D, G). Idiosoma, length × width, 435 (425–450) × 220 (205–225), length of hysterosoma 290 (280–295). Prodorsal shield: length along midline 135 (130–140), greatest width posterior to level of scapular setae 150 (145–155), anterior part at level of trochanters II not narrowed, anterolateral extensions angular, almost extending to bases of epimerites Ia, lateral margins not fused with scapular shields, posterior margin straight, surface without ornamentation. Internal scapular setae si spiculiform, 30 (27–30) long, separated by 60 (60–65); external scapular setae se separated by 100 (100–105). Setae c2 thin spiculiform, 50 (45–50) long, situated in anteromedial angle of humeral shields. Setae c3 narrowly lanceolate, with acute apex, 23 (22–24) long. Hysteronotal shield completely separated into prohysteronotal and lobar parts, total length 275 (270–280). Prohysteronotal shield: length along midline 175 (170–180), width at anterior margin 145 (140–155), lateral margins at level of trochanters III with small incisions flanked by bean-shaped heavily sclerotized patch, DHA absent, surface without ornamentation. Dorsal setae d1, d2, e2 present. Setae f2 absent. Length of lobar shield excluding terminal lamellae 98 (95–105). Opisthosoma strongly attenuate posteriorly, opisthosomal lobes fused with each other along midline forming a heavily sclerotized median septum, only apical parts of lobes posterior to level of setae h2 separated by narrow parallel-sided terminal cleft; length of cleft from anterior end to lobar apices 27 (25–28); length from anterior end to apices of terminal lamellae 63 (60–65), width 7 (6–7). Terminal lamellae semi-ovate, with noticeably attenuate apices, with smooth margins, length from bases of setae h3 to lamellar apices 42 (38–42), greatest width 30 (27–30). Distance between dorsal setae: c2:d2 65 (63–75), d2:e2 92 (90–95), e2:h2 77 (75–80), h2:h3 25 (23–25), h2:h2 45 (42–45), h3:h3 30 (30–32), d1:d2 42 (37–42), e1: e2 42 (38–42).

Epimerites I free. Rudimentary sclerites rEpIIa semi-round of shaped as inverted teardrop with small central lacuna. Genital apparatus: length excluding basal sclerite 48 (45–48), greatest width 20 (18–21), epiandrum small ovate, latigenital sclerites absent, distal ends of parameres without denticles, aedeagus as short conoid (frustum). Anterior and posterior genital papillae subequal in size. Postgenital plaque almost circular in shape. Setae g narrowly lanceolate (about 3 wide) with filiform apices, with bases clearly separated and surrounded by small cordiform sclerotized areas (rudiments of genital shield), not fused each other. Apophyses of adanal apodemes shaped as ridges with almost rectangular ledge at anterior end. Lateral margins of opisthosoma with barely distinct lateral membranes. Translobar apodeme present. Adanal shields represented by small triangular sclerites around bearing setae ps3. Adanal suckers 15 (14–17) in diameter. Inner ends of epimerites IIIa with apices extending to level of setae 4b, without denticle-like extensions on inner margins. Epimerites IVa wide, with anterior ends bifurcate, indented and not reaching levels of basal sclerite and setae 4a. Setae 4b situated anterior to level of setae 3a; setae g slightly posterior to level of setae 4a. Distance between ventral setae: 4b:3a 7 (7–10), 4b:g 85 (78–85), g:g 10 (10–12), g:ps3 52 (50–57), ps3:h3 100 (97–105).

Setae cG, mG of genua I, II filiform. Genual solenidia σ I and σ II situated at midlength of corresponding genua ( Fig. 19A, B ). Trochanteral setae sR III narrowly lanceolate, with acute apex, 15 (15–16) long. Legs IV with ambulacral disc extending to level of setae h3. Tarsus IV 38 (35–38) long; modified setae d barrel-shaped, with discoid cap, situated in distal one third of this segment; modified setae e button-like, without cap, situated apically ( Fig. 19C ). Length of solenidia: σ I 58 (58–65), σ II 15 (13–15), σ III 25 (23–27), φ IV 35 (35–38).

FEMALE (range for 10 paratypes) ( Figs. 18 , 19E, F ). Idiosoma, length × width, 495–535 × 210–225, length of hysterosoma 340–370. Prodorsal shield: shaped generally as in male, posterior margin straight or slightly convex, 135–140 long, 150–160 wide, surface without ornamentation. Setae si thin spiculiform, 27–30 long, separated by 62–68; setae se separated by 105–110. Setae c2 spiculiform, 40–48 long, situated in anteromedial angle of humeral shields. Setae c3 narrowly lanceolate, with blunt apex, 20–24 long. Hysteronotal shield: length from anterior margin to posterior tips 320–340, width at anterior margin 145–155, lateral margins at level of trochanters III with incision flanked by bean-shaped heavily sclerotized patch, DHA absent, central area from level of setae c3 to trochanters IV with small and poorly distinct ovate lacunae, posterior part with dash-like lacunae. Dorsal setae d1, d2, e2 present. Setae h1 narrowly lanceolate, 28–35 long, situated anteromesal to bases of setae h2, 20–22 from corresponding lateral margins of hysteronotal shield, with tips extending beyond free margin of interlobar membrane. Width of opisthosoma at level of setae h2 92–105. Setae ps1 situated dorsally, equidistant from margins of opisthosomal lobes, distinctly closer to setae h3 than to h2. Supranal concavity open posteriorly into terminal cleft. Length of terminal cleft from anterior end of supranal concavity to lobar apices 140–155, length from free margin of interlobar membrane to lobar apices 110–120, greatest width of cleft 45–50. Interlobar membrane occupying anterior 1/8th of terminal cleft. External copulatory tube straight stylet-like, with acute apex, situated on free margin of interlobar membrane, 27–30 long; basal guides of copulatory tube well developed, primary spermaduct guide in supranal concavity poorly sclerotized. Distance between dorsal setae: c2:d2 75–80, d2:e2 85–90, e2:h2 57–62, h2:h3 70–75, h2: h2 78–88, h3:h3 50–67, d1:d2 45–48, e1: e2 30–35, h1:h2 12–20, h1:h1 45–47, ps1:h3 15–20.

Epimerites I free. Epigynum 44–48 long, 92–98 wide. Inner margins of epimerites IIIa with small blunt-angular extension. Epimerites IVa short and wide. Anal opening with small adanal sclerites. Setae f2, ps2 present. Head of spermatheca with semi-ovate peak; primary spermaduct without enlargement, and straight or slightly sinuous before entering into external copulatory tube; secondary spermaducts 28–32 long ( Fig. 19E ).

Legs I, II as in males ( Fig. 17A, B ). Trochanteral setae sR III narrowly lanceolate, with acute apex, 13–17 long. Legs IV with ambulacral disc extending to midlength between levels of setae h2 and h3. Length of solenidia: σ I 58–65, σ II 16–18, σ III 24–25.

Differential diagnosis. Among species of the capensis group having setae d1, Trouessartia helmitheros sp. n. is most similar to T. americana in having, in males, the postgenital plaque almost circular in shape, setae g narrowly lanceolate and surrounded by small sclerotized areas, and, in females, the external copulatory tube acute and stylet- like. Trouessartia helmitheros sp. n. differs from T. americana by the following features: in males, the anterior and posterior genital papillae are subequal in size, the rudimentary sclerites rEpIIa are semi-rounded or an inverted teardrop shape, the anterior ends of epimerites IVa are usually bifurcate, and the anterior ends of the adanal apodemes are blunt-angular; in females, the primary spermaduct before entering into the copulatory tube is straight or slightly sinuous, and the posterior part of the hysteronotal shield bears mostly small dash-shaped lacunae. In males of T. americana , the anterior genital papillae are larger than posterior ones, the rudimentary sclerites rEpIIa are small and ovate, the anterior ends of epimerites IVa are pointed, and the anterior ends of the adanal apodemes have rounded tubercles; in females, the primary spermaduct makes a S-shaped bend before entering into the copulatory tube, and the posterior part of the hysteronotal shield bears both dash-like (medially) and small ovate lacunae (laterally).

Etymology. The specific epithet is taken from the generic name of the type host.

Figures

FIGURE 17. Trouessartia helmitheros sp. n., male. A—dorsal view, B—ventral view.

FIGURE 18. Trouessartia helmitheros sp. n., female.A—dorsal view, B—ventral view.

FIGURE 19. Trouessartia helmitheros sp. n., details.A, B—genu, tibia and tarsus I, II of male, respectively, C—tibia and tarsus IV of male, D—setae si, c2, c3 and sRIII of male, E—spermatheca and spermaducts, F—opisthosoma of female, dorsal view, G—opisthosoma and genital apparatus of male, ventral view.