Antennoseius (Vitzthumia) perseus, Beaulieu & Déchêne & Walter, 2008

Beaulieu, Frédéric, Déchêne, Andrea D. & Walter, David E., 2008, Phase morphs and phoresy: New species of Antennoseius (Vitzthumia) mites (Acari: Mesostigmata: Ascidae) associated with pyrophilous carabids (Carabidae: Sericoda spp.) in Alberta, Canada, Zootaxa 1961 (1), pp. 37-57 : 39-48

Antennoseius (Vitzthumia) perseus sp. nov.

( Figs 1–19 )

Material examined. ALBERTA: Holotype. Female, under elytra of Sericoda quadripunctata (DeGeer) ex pitfall traps in recently burned boreal forest near Chisholm (54°56’N, 114°7’W), 22 July 2002. Paratypes: 49 females, under elytra of Sericoda quadripunctata (DeGeer) and S. bembidioides ex pitfall traps; 2 females under elytra of Calathus ingratus Dejean , same collection data; 2 females and 5 males (granular morph) obtained from rearing females collected on carabids.

Diagnosis. Antennoseius species with adult females of smooth (phoretic) morph lacking granular tubercles on shields and soft cuticle: soft cuticle plicate; dorsal and peritrematal shields with reticulate pattern; ventral shields weakly lineate. Podonotal shield with 20 (rarely plus r3 asymmetrically attached) pairs of setae, including an additional pair x, laterad s4; opisthonotal shield with 15 pairs of setae. Most idiosomal setae simple, but podonotal setae j2-5 and z2 short, spur-like; opisthonotal seta Z5 about twice as long as others and lightly barbed in distal half. Sternal shield bearing st1-2 and stp1-2; postero-lateral margins eroded leaving st3 and stp 3 in soft cuticle; st 4 in soft cuticle. Anal shield with 3 circum-anal setae. Hypostomal setae h1-3 simple; pc swollen basally and with fine, acuminate tip; palpal setae simple except al of femur and al1-2 of genu thickened. Leg I with ambulacrum; seta pl2 absent on tibia III. Most leg setae simple to sparsely barbed, except the following setae spur-like (thick, and usually blunt): dorsal seta on trochanter I; ad1, pd1, pd2 on femur I; and pd2, pd3 on genu I. Coxae I–II each with a seta with swollen base, and fine, acuminate tip.

Adults of granular morph without spur-like podonotal setae or swollen setae having hair-like tips on subcapitulum or coxae. Surface of adults with dense coating of small tubercles and secondary pattern of larger tubercles forming reticulations on podonotal, opisthonotal, ventri-anal shields, and lateral region of peritrematal shield. Soft cuticle plicate and covered with small tubercles. Adult female podonotal shield with 20–22 pairs of setae, including an additional pair x, laterad s4; setae uniformly short, bushy, except z1 thin, sparsely barbed; j1 larger, swollen; opisthonotal shield truncate posteriorly with 14 pairs of short, bushy setae, except Z5 thicker, about 1.5–2 × length of other opisthonotal setae. Seta S1 off shield. Sternal shield lineate, bearing setae st2-3, stp1-3, st 1 in soft cuticle in pre-sternal region posteriad a pair of well developed pre-sternal sclerites; st 4 in soft cuticle. Ventri-anal shield with 7 setae (JV2-3 captured). Leg I with ambulacrum; seta pl2 absent on tibia III; all leg setae simple, most dorsal and lateral setae barbed. Adult male granular ornamentation similar to female but with podonotal and opisthonotal shields fused laterad z -Z series, free to irregularly fused medially and separated by narrow band(s) of soft cuticle. Sterno-genital shield lineate, bearing st1-5, stp 1-3; pre-sternal platelets present. Spermatodactyl simple, with rounded tip, slightly longer than movable digit.

Description of phoretic female (smooth morph). Soft cuticle evenly plicate. Anterior dorsal shield (265–308 long × 270–310 wide) and posterior dorsal shield (230–258 × 257–288) both with smoothly angular reticulate ornamentation throughout ( Figs 1–2 ). Anterior shield with 20 pairs (j1-6, z1-6, s1-6, x, r2, + r3 rarely captured asymmetrically) of mostly short (24–30), acicular setae; j1 (12–20) somewhat thickened; z1 similar in length to j1 but more slender; j2-5 (13–15) and z2 (13–14) short, stout (4 wide) and spur-like, usually blunt apically; j6 and z5 (17–22) intermediate between setiform and spiniform, sometimes blunt. Posterior shield with 15 pairs of mostly short (21–31), acicular setae (J1-5, Z1-5, S1-5); Z5 (38–44) longest, sparsely barbed in distal half. Marginal setae r3-6 and R1-8 short (17–23), acicular, in soft lateral cuticle. Peritreme extending to near seta z1, peritrematal shield with elongate cells laterally, smooth in exopodal shield laterad coxae III–IV and parapodal region, joined to anterior dorsal shield near seta s1. Dorsal shields with 23 pairs of discernible pore-like structures (9 on anterior shield, 14 on posterior shield), of which 7 appear secretory (gland pores, gd, Fig. 1 ) and 16 non-secretory (lyrifissures). Gland pore gds5? apparently corresponds to gd4 sensu Athias-Henriot (1971, 1975). Gland pores are slit-shaped and lyrifissures are generally ovoid except those laterad setae j1 and Z5.

Tritosternum base (30–39) with 8–12 denticles fringing distal end around base of laciniae (54–65). Sternal shield (length 123–126 including median process, narrowest width between legs II, 89–94) ( Fig. 3 ), lineate laterally and anteriorly, bearing simple setae st1 (23–26), st2 (20–23) and lyrifissures stp1-2; transverse ridge across shield at level of stp1; stp2 on posterior margin; shield deeply but evenly notched postero-laterally, median process irregularly truncate. Small endopodal plate posteriad coxa II separated from sternal shield by soft cuticle. Setae st3-4 (20–24) and lyrifissure stp 3 in soft cuticle. Epigynial shield (130–139 long) ( Fig. 3 ) with membranous anterior margin, narrow stem (24–29 wide), and oval posteriorly (45–55 wide), bearing setae st5 on margin and a few faint lines. Metapodal plates oval (11–12 × 22–23). Anal shield (105–126 long × 94–105 wide) pear-shaped, faintly lineate, usually with 3 simple circum-anal setae, post-anal seta (20–22) slightly longer than para-anal setae (17–20); shield sometimes capturing ventral seta JV3; cribrum in terminal tuft. Soft cuticle with simple ventral setae JV1-5, ZV1-5, and 4–8 pairs of simple submarginal setae (UR ’s) ( Figs 1, 3 ).

Tectum ( Fig. 4 ) with anterior medial margin denticulate, and dorsal surface with a transverse line of denticles; subcapitulum ( Fig. 5 ) with 7 rows of 4–11 deutosternal denticles, ridges of some rows extending onto genae; corniculi horn-like (40–43), extending to distal margin of palptrochanter; hypostomal setae h1-3 simple; palpcoxal seta pc swollen basally, with fine, acuminate tip ( Figs 5–6 ). Fixed digit of chelicera (35–38, from dorsal lyrifissure) with short, rounded dorsal seta, row of 12–17 serrations, setiform pilus dentilis, and subapical offset large tooth; movable digit (41–46) bidentate and paraxial ridge leading to a ventral projection typical for the genus ( Fig. 7 ). Palps (138–155) less than twice the length of subcapitulum (from base to tip of corniculi: 115–117); palpal setae simple except al of palpfemur and al1-2 of palpgenu thickened; setation normal for genus; palp apotele 2-tined.

Excluding ambulacra, lengths of leg I 468–505, leg II 317–351, leg III 312–352, leg IV 440–479 ( Figs 8– 9 ). Tarsus I with ambulacrum (12–14, excluding stalk) on short stalk (8–10), claw subequal in size to claws of tarsi II–IV; ambulacra II–III (26–32), IV (34–36). Tarsus I (107–118) less than twice as long as tibia (71–78) or genu (90–96). Tarsi II–III (90–101) and IV (131–139) about as long as combined length of tibia and genu; tibiae II–III (42–49) and tibia IV (65–68) equal or subequal to genua. Setation of leg segments I–IV, respectively: coxae 2-2-2-1, posterior seta on coxae I–II swollen basally, with fine, acuminate tip ( Fig. 8 ), as in seta pc; trochanters 6-5-5-5, dorsal seta on trochanter I spine-like, sparsely barbed; femora 12-11-6-6, dorsal setae ad1, pd1, pd2 on femur I spur-like, pd2 on femur I spine-like ( Fig. 8 ); genua 13-11-9-9, dorsal setae pd2, pd3 on genu I spur-like, pd1 slightly thickened ( Fig. 8 ); tibiae 13-10-8-10, seta pl2 absent on tibia III ( Fig. 9 ); tarsi II–IV 16-16-16, plus two short apical seta-like processes. Most dorsal setae and a few lateral setae on femora, genua, and tibiae II–IV, and a few dorsal setae on tarsi II–IV sparsely barbed ( Fig. 9 ), others simple (acicular) or spine-like as noted above. Tarsus I with 4 long (75–83), slender setae subapically.

Description of free-living female (granular morph). Soft cuticle plicate and covered with small tubercles except in regions surrounding epigynial and sternal shields. Anterior dorsal shield (315–335 long × 395– 410 wide) and posterior dorsal shield (290–310 long × 330–345 wide) both with granular colliculate ornamentation throughout ( Fig. 10 ). Anterior shield with 20–22 pairs (j1-6, z1-6, s1-6, x, r4, +/- r2 and r3) of mostly short (22–27 long × 5–6 wide), bushy setae, j1 (28–34 long × 10–13 wide) inflated, z1 (12–16 × 2 wide) shortest and slender; r5-6 (+/- r2-3) in soft cuticle; posterior shield with 14 pairs of mostly short (24–28), bushy setae (J1-5, Z1-5, S2-5); Z5 longest (37–39); S 1 in soft cuticle between shields. Marginal setae R1-8 short (20–22), bushy, in soft lateral cuticle. Peritreme extending to near seta z1, peritrematal shield lineate tuberculate laterally, smoothly lineate in exopodal shield laterad coxae III-IV and parapodal region, joined to anterior dorsal shield between setae s1 and z1. Dorsal shields with 22 pairs of discernible pore-like structures (9 on anterior shield, 13 on posterior shield), of which 7 appear secretory (gland pores, gd, Fig. 10 ) and 15 nonsecretory (lyrifissures). Lyrifissure ids6 occurs in soft cuticle mesiad seta S1.

Tritosternum as in phoretic morph. Sternal shield ( Fig. 11 ) (median length 120–135, narrowest width between legs II 96–98) slightly notched at level of lyrifissure stp2, lineate laterally, with two faint median lines; st1 (28–36) in soft cuticle anterior to shield; st2-3 (29–30) and lyrifissures stp1-3 on shield; small endopodal plate posteriad coxa II separated from sternal shield by soft cuticle. Setae st4 (20–23) in soft cuticle. Epigynial shield (130 long) ( Fig. 11 ) with membranous anterior margin, expanded posteriorly (77 wide) with somewhat truncated margin, bearing setae st5 on margin and a few faint lines. Metapodal plates (22–25 long × 13–15 wide) irregularly oval. Ventri-anal shield (165–172 long × 193–200 wide) reticulate-tuberculate, bearing 7 simple setae, JV2-3 (+ JV4 present on one side of one specimen) and circum-anal setae, post-anal seta (21–26) less than twice as long as para-anal setae (13–14); cribrum in terminal tuft. Soft cuticle with ventral setae JV1, ZV1-ZV2 simple, and JV4-5, ZV3-5 and 4–5 pairs of submarginal setae (UR ’s) thick and barbed.

Gnathosoma ( Figs 12–13 ) as in phoretic morph except the following: palpcoxal seta pc simple and pd1 of palpfemur lightly barbed; palps (150–170), subcapitulum (127) and movable digit (48–50) slightly longer; dorsal seta of chelicera broad and flattened.

Legs ( Figs 14–15 ) as in phoretic morph, except the following: legs I (561–563), II (405–411) and III (380–381) slightly longer, leg IV of similar length (470–498); setae on coxae all simple; no spine- or spur-like setae on trochanter, femora and genua, but dorsal seta on trochanter I and pd2 on femur I short, barbed and somewhat spine-like ( Fig. 14 ); leg setae, including of leg I, more often and more densely barbed than in phoretic morph: some dorsal setae on femora I–IV, all dorsal setae on genua and tibiae I-IV, nearly all lateral setae on genua and tibiae II–IV, and a few dorsal setae on tarsi II-IV barbed. Ambulacrum I (7–10) on short stalk (7–9), but shorter than in phoretic morph. The 4 subapical setae on tarsus I longer (103–130) than in phoretic morph.

Male. Podonotal and opisthonotal shields ( Fig. 16 ) fused laterad z -Z series, sometimes also irregularly fused medially (therefore with 1–3 central narrow band(s) of soft plicate cuticle, as in Fig. 16 ), combined length 499–520 × 231–345 wide, similar in ornamentation to free-living female; more expanded than in female, bearing all 47 pairs of mostly short (19–24 long × 4–5 wide) bushy dorsal setae (j1-6, z1-6, s1-6, x, r2- r6; J1-5, Z1-5, S1-5, R1-8); j1 (22–26 × 10–12) inflated; s1-s2, marginal setae (r -R) and additional seta x slightly shorter (17–22); z1 shorter and slender (10–13 × 2); Z5 longest (30–35). Peritrematal shield joined to dorsal shield near setae r2 or r3. Sterno-genital shield ( Fig. 17 ) smooth medially, lineate laterally, bearing 5 pairs of tapered, simple setae (20–29), anterior pairs (st1-3) longest (25–29). Ventri-anal shield ( Fig. 17 ) broad, almost abutting peritrematal shield and dorsal shield; smoothly lineate anteriorly, reticulate and densely covered with small rounded tubercles over most of surface, bearing 7 pairs of ventral setae (JV1-4, ZV1-3) (16–20), mostly simple but ZV3, JV4 bushy; JV5 (22–27) bushy, in soft cuticle; no submarginal setae; soft cuticle covered with small tubercles as in free-living female.

Gnathosoma ( Figs 18–19 ) as in female free-living morph except slightly shorter setae, palps (152–158), corniculi (38) and subcapitulum (97); chelicera ( Fig. 19 ) with fixed digit (32–33) with 7–8 denticles; movable digit (37–41) with one tooth and spermatodactyl (from articulation with digit: 40–45) slightly longer than digit, curves ventrad about mid point, then straightens in last quarter to tapered, rounded tip.

Legs as free-living female, except the following: leg segments approximately 10% shorter than free-living female; some setae on trochanters and femora can be more or less barbed than in free-living female; ambulacrum I (12–16; stalk 8–12) longer than in free-living female, other ambulacra of similar length.

Etymology. The specific name perseus is a noun in apposition, derived from the Greek mythological demigod Perseus, who rode the winged horse Pegasus and decapitated the Gorgon Medusa.

Remarks. Among Antennoseius species with an ambulacrum on leg I, adult females of the smooth (phoretic) morph of A. perseus resemble those of A. bregetovae Chelebiev and A. ranikhetensis Bhattacharyya in having no granular tubercles on shields and soft cuticle, some setae in the j and z series short and spur-like, 1 or 2 spur-like setae (with hair-like processes in A. perseus and A. bregetovae ) on coxae I and II, one or more dorsal spines on trochanter, femur and genu I, and an anal shield bearing only 3 circum-anal setae. It differs from A. bregetovae by having 5 spur-like setae on the anterior dorsal shield instead of 4 (in the description of A. bregetovae , it is not clear whether j2-j5 are spur-like, or rather j2-3, j5 and z3; Chelebiev 1984); only 1 spur-like seta on coxa I instead of 2; 3 spine- or spur-like dorsal setae on femur I instead of apparently only 1 in A. bregetovae ; 2 spur-like dorsal setae on genu I instead of 1, setae pc of the subcapitulum spur-like with hair-like process, and setae st3 on soft integument rather than captured by the sternal shield. It differs from A. ranikhetensis by having setae j2-j5 and z2 spur-like instead of j2-3, z2-4 and s4, different spine-like setae on femur and genu I, and a sternal shield more eroded on the posterolateral corners and with a posterior median process.

The spur-like setae in the j and/or z series make the phoretic morph of A. perseus also similar to a few Antennoseius s. str. species, such as A. pannonicus Willmann and A. imbricatus Ishikawa. However , A. perseus differs from those in part by having an ambulacrum on leg I and a different set of spur-like setae on the anterior dorsal shield.

Adult females of the granular (presumably free-living) morph of A. perseus resemble those of A. belajevi Bregetova and A. janus Walter & Lindquist (granular morph) in having granular tubercles all over (as well as forming the reticulate patterning itself) the dorsal and opisthogastric shielding and on the soft integument, and setae on dorsal shields all barbed and almost uniform in appearance (j1 is thicker and longer, as well as Z5, at least in A. perseus ). They also resemble those of A. belajevi in having 2 pairs of ventral setae in addition to the 3 circum-anal setae on the ventri-anal shield, but differ in having truncated posterior dorsal shield and epigynial shield, 1 more seta in the area occupied by s3-s4 and r2-r4 on the anterior dorsal shield, S1 off posterior dorsal shield, and no unpaired seta on dorsal shields (the drawing of A. belajevi shows an unpaired seta between j2 setae). They differ from granular females of A. janus mostly in having 2 pairs of ventral setae in addition to the 3 circum-anal setae on the ventri-anal shield, 8 setae on tibia III instead of 9, S1 and R1 setae off the posterior dorsal shield, and setae j1 and Z5 more inflated.

Phoretic (smooth) females were mostly found on the ventral surface of the beetles' elytra, while fewer than 5% of females were under or between the two folded wings. Typically 2–3 individuals were found on the same beetle, and were spread evenly under the elytra, though when more than 10 females were on the same beetle they were packed in rows of three across with individuals of the next row slightly overlapping. One of us ( DEW) has recently seen a granular morph female collected from soil in a more northern site in Alberta, supporting our presumption that this morph is non-phoretic. This species is a voracious nematophage .

Figures

FIGURES 1–4. Antennoseius perseus n. sp., female, phoretic form. 1, Dorsal shields; 2, Scanning electron micrograph of anterior portion of podonotal shield and most of leg I; 3, Ventral shields; 4, Tectum.

FIGURES 5–9. Antennoseius perseus n. sp., female, phoretic form. 5, Subcapitulum; 6, Scanning electron micrograph of palpcoxal seta; 7, Right chelicera, lateral (antiaxial) view; 8, Right leg I (except tarsus), postero-lateral view; 9, Right leg III, dorsal view.

FIGURES 10–13. Antennoseius perseus n. sp., female, free-living form. 10, Dorsal shields; 11, Ventral shields; 12, Subcapitulum; 13, Right chelicera, lateral view.

FIGURES 14–15. Antennoseius perseus n. sp., female, free-living form. 14, Right leg I (except tarsus), postero-dorsal view; 15, Right leg III, postero-dorsal view.

FIGURES 16–19. Antennoseius perseus n. sp., male. 16, Dorsal shield; 17, Ventral shields; 18, Tectum; 19, Right chelicera, lateral view.