Fungiseius armatus, Moraza, María L. & Lindquist, Evert E., 2011

Moraza, María L. & Lindquist, Evert E., 2011, A new genus of fungus-inhabiting blattisociid mites (Acari: Mesostigmata: Phytoseioidea) from Middle America, with a key to genera and subgenera of the subfamily Blattisociinae, Zootaxa 2758, pp. 1-25 : 6-14

Fungiseius armatus new species

( Figs 1–37 , 59 )

Diagnosis. Adults with the following apomorphic attributes: dorsal shield hypotrichous, lacking podonotal setae z3, z6 and opisthonotal setae J1-J3; J5 minute; idiosoma distinctly elongated; female opisthogaster with anal shield; palps bowed or angled inwards at juncture of trochanter and femur, and with inner seta of palptrochanter strongly curved, elongate, apposed to modified anterolateral seta of palpfemur. Legs I–II chaetotaxy reduced: trochanter I with four or five setae (av and sometimes d absent), genu I and tibia I each with 12 setae, lacking av -2; genu II with ten setae, lacking ad -3. Leg II, seta pv -1 on tibia spine-like; pl -3 on basitarsus, and pl -1, pd -2, md, pv - 1 and pv -2 on telotarsus strongly thickened, claw-like; other tarsal setae spine-like. Leg III, seta md on tarsus thicker and longer than other tarsal spine-like setae. Leg IV, two setae on tarsus (md, ad -2) conspicuously thickened, claw-like.

Description. ADULT FEMALE. Dorsal shield 462–542 long, 208–230 at its greatest width at level of setae r3; shield lightly reticulate-punctate over most surface ( Figs 9, 14 ) but nearly smooth on either side posterolaterally; shield with delineated lateral rim extending from setae z2 to S5 and bearing s3, S1-S5; shield vertex arched downwards, concealing insertions of setae j1 and z1 from above ( Figs 11 a–b); shield with 27 pairs of attenuated, smooth setae. Dorsal setae of generally similar, moderately short lengths, except J5 much shortest (2–3); z1, s1-s2, r3 also short (5–10); j1 (13–15) slightly shorter than most other setae; j2-j6, z2, z5, S1-S3 (17–22) slightly shorter than z4, s3-s6, Z1, S4, S5 (24–30); Z4 (35–40) longest, followed by subequally long Z2, Z3, Z5 (30–35) ( Fig. 13 ). Lateral soft cuticle with usually six pairs of simple setae s2 (11), r4-r6, R1, R4 (11–20). Peritrematal plates uniting with dorsal shield anteriorly at level of setae z1 ( Fig. 11 a) or free ( Fig. 11 b); peritremes long, apices reaching anteriorly to level of setae z1 where concealed from dorsal view ( Figs 11 a–b).

Tritosternum ( Fig. 5 ) with base nearly as long (8–9) as wide (12–14), with laciniae peculiarly aristate in form, free for about 0.7 to 0.8 of total length (55–60 excluding base), their fused area with sparse denticles. Presternal area ornamented with pair of weakly sclerotized plates consolidated with sternal shield ( Fig. 15 ). Sternal shield midlateral length from anterior margin at level between setae st1 to posterior margin 108–112, narrowest width between legs II 82 –92, finely punctate over entire surface ( Fig. 17 ) and lineate along lateral margins, posterior margin slightly concave; shield with strong endopodal extensions between coxae I–II which bear gland pore gst1 distally, and with well developed extensions between coxae II–III. Sternal setae st1 (26–35) about twice as long as st2- st4 (12–17), st4 on well sclerotized metasternal plates with poroids iv3 on paraxial lateral margin of the plates.

Endopodal strips moderately developed between coxae III and IV. Epigynal shield 150–165 long, 68–80 wide at level of posterior margin, reticulated, with wide cells (eight) on posteromedial region and elongated cells elsewhere, axe-shaped, with truncate posterior margin embedded in deep postgenital fold of soft cuticle; genital setae st5 (17–20) slightly longer than st2-st4. Paragenital poroids iv5 on soft cuticle well removed from posterolateral margins of epigynal shield. Anal shield reticulate, elliptical, midlength (67–75) greater than width at level of glandular pores between paranal and postanal setae (55–62), with paranal setae (12–15) less than half as long as postanal seta (35–40). Soft cuticle with nine pairs of opisthogastric setae, JV2 and JV5 longest (30–38), JV1 (20–23) slightly longer than others (JV4, ZV1-ZV 5 12–19), flanked by posteriormost pair of marginal setae, R4. Peritrematal shield strongly developed posterior to stigma, where consolidated with exopodal strip curving behind coxa IV and bearing poroids ip2, ip3, and gland pores gp3, gv2 ( Figs 12 , 15, 16 ). Metapodal plate length 22–27, width 10–12. Spermathecal apparatus with small (ca. 40), tubular, thinly sclerotized calyx, and a long minor duct arising from embolus of calyx ( Fig. 18 ).

Gnathotectum with anterior margin irregularly convex to nearly truncate, finely denticulate ( Fig. 1 ). Cheliceral shaft, excluding basal section, 108–115 long, with stout digits ( Figs 8 a–b); dorsal face of fixed digit with short (8– 9) acutely tapered dorsal seta; fixed digit with small (3–5) pilus dentilis, with row of seven to ten small teeth along apical half of masticatory surface and two offset subapical teeth; movable digit (38–42) with row of three coarse retrorse teeth. Corniculi ( Fig. 3 ) strongly developed (40), with medial edges and pointed apices well-separated but slightly convergent; internal malae shorter than corniculi, with fringed lateral margins ( Fig. 2 ). Deutosternum with seven (rarely eight) rows of denticles sparsely multidenticulate (6–8 teeth), gradually widening from apical to basal row. Subcapitulum with setae pc (9–10) shorter than hp3 (13–19) and hp1 (18–20), lateral pair hp2 minute (2), spine-like. Palpi (100–110) bowed or angled inwards at juncture of trochanter and femur; palptrochanter with inner seta strongly curved, much longer (32–40) than outer seta (5–9); palpfemoral seta al (22) rodlike, with angulartruncate tip ( Fig. 7 b), dorsal setae thickened, spine-like, with thin tips; palpgenual setae al -1 and al -2 slightly spatulate, both with rounded tips ( Fig. 7 a); palptarsal claw with two tines spatulate with rounded tips ( Fig. 6 ).

Legs I–IV of similar lengths, shorter than dorsal shield length; legs IV slightly longest (328–375, excluding pretarsus), about two-thirds (0.67–0.71) as long as dorsal shield ( Fig. 59 ); other leg lengths, excluding pretarsi: I 295–318, II 317–335, III 290–325. Leg II nearly twice as thick as other legs (coxa and genu II about 2.0 as wide as coxa and genu I) ( Figs 19–20 , 59 ). Legs III and IV with tarsus about 2.0–2.1 and 1.7–1.8 times, respectively, as long as tibia. Tarsi II–IV with pair of apical setal processes ad -1, pd -1 conspicuous (14–20), nearly as long as length of pretarsus to base of claws (17–22) ( Figs 27–31 ). Tarsi II–IV with apical ventral process well developed (9–12), acutely triangular, 0.5 as long as length of pretarsi to base of claws ( Figs 30–31 ). Leg I segment length ratios, femur: genu: tibia: tarsus, about 1.0: 0.6: 0.6: 1.0; tarsus (68–72) and femur (65–75) subequal, longer than genu (40–47) and tibia (40–50); length of pretarsus I to base of claws (15–17). Coxae II–IV lineated on ventral surface ( Figs 19–23 ); coxal setae simple, moderately long (9–24). Legs I to IV with chaetotactic formulae of segments as described for genus. Leg I with slightly spine-like setae pd -1 (37) on genu and pd -1 (19), pl -1 (38–42) on tibia, and with seta pv -1 attenuated (25–27) on each of coxa, trochanter, femur, genu, tibia ( Fig. 19 ); tarsus I with dorsal basal seta pd and three of distal setae elongated (50–60) ( Fig. 25 ). Legs otherwise without notably long setae ( Figs 19–23 ). Leg II with seta pv -1 slightly spine-like (21) on tibia ( Fig. 20 ); seta pl -3 strongly thickened, spurlike (34) on basitarsus, and five setae, pl -1 (30), pd -2 (32), md (46), pv -1 and pv -2 (13), strongly thickened, spurlike or clawlike, on telotarsus; other tarsal setae short, slightly spine-like ( Fig.27 ). Leg III with tibial setae ad -1, pd -1 and pd -2 short, slightly spine-like ( Fig. 21 ), tarsal setae collectively more or less spine-like, basitarsal ad -3, pd -3 (17), telotarsal ad -2, pd -2 (24) and especially md (28) the thickest ( Fig. 28 ). Leg IV, trochanter and femoral seta v somewhat elongated such as on leg I (ca 30), femoral v aligned proximal to al - 1 in an anterolateral position ( Fig. 22 ); basitarsal setae ad -3, pd -3 (15) slightly spine-like; telotarsal setae ad -2 (32) and md (37) strongly spine-like, md thickest and blade-like; other ventral and lateral tarsal setae thinner, some slightly spine-like ( Fig. 29 ). Paired claws on tarsi I–IV with small basal swelling ( Fig. 30 ).

ADULT MALE. Dorsal shield as large as in female, 452–495 long, 212–227 at its greatest width at level of setae r2; shield form, ornamentation, and setation as in female except seta s2 on dorsal shield. Form and size of dorsal shield setae as in female. Lateral soft cuticle with r2-r5, R1 and one or two other R -marginal setae. Peritrematal shields and peritremes as in female, peritremes reaching anteriorly to level of setae z1.

Tritosternum as in female but smaller, with base as long (9) as wide, and laciniae total length 35 excluding base. Sternitigenital shield midlateral length 185–215, width 73–82 at level between coxae II, with five pairs of setae of dissimilar lengths, st1 longest (30), st2-st5 (11–17), and three pairs of poroids. Endopodal extensions from sternitigenital shield between legs I–II and II–III very strong, as in female; endopodal strips alongside coxae III–IV well developed, partially free from sternitigenital shield ( Fig. 37 ). Ventrianal shield ornamented with squamous reticula; mid-length (155–165), greatest midlateral width (140–155) at level of setae JV2, with regularly convex lateral margins, bearing four pairs of opisthogastric setae JV1 (20), ZV1 (9), JV2 (32), ZV2 (21) and paranal setae (15) less than half as long as postanal seta (37–40); soft opisthogastric cuticle with two pairs of setae, JV4 (15–19) and JV5 (35), and three pairs of poroids. Metapodal plates entire or in two well-separated pieces.

Gnathotectum as in female. Cheliceral fixed digit with minute pilus dentilis and row of six coarse teeth ( Fig. 34 ); movable digit (35–40) with one tooth and apical hook ( Fig. 35 ); spermatodactyl slightly undulate, finger-like (34), with a short apical process (8) ( Figs 33, 35, 36 ). Corniculi shorter (26), stout, with their apices more flared than in female, with a ventrolateral bulge (not present in female); internal malae slightly longer and more acute apically than in female ( Fig. 32 ). Subcapitulum with rows of deutosternal denticles and lengths of setae (including hp2 minute, spine-like) as in female. Palpi (100–105) with form and structures as in female.

Relative leg lengths, excluding pretarsi, similar to those of female, I (295–310), II (315–327), III (285–302), IV (335–357). Leg I segment lengths and their ratios as in female, femur (61–65), genu (37), tibia (40), tarsus (70– 72). Leg I, genual seta pl -1 elongated, tibial seta pl -1 thickened, seta pv -1 on coxae to tibia long and with thin end. Leg II, tibial seta pv -1 slightly thickened, spine-like, tarsus II seta pv -1 much smaller than on female. No other male dimorphism noted among leg setae. Legs III and IV thickened setae on tarsus as in female.

Type material. All adult specimens from samples collected from the area of the La Selva Biological Station, Heredia Province, COSTA RICA (10° 26' 1" N, 84° 1' 2" W, elevation 50–150 m). HOLOTYPE: female, 345 m along Holdridge trail, ex fungus, 18 April 1995, coll. ALAS. PARATYPES: 3 females, 1 male, with same data as holotype; 12 females, 1 male, 300 m along Occidental trail, ex polypore fungi on canopy-shaded log, 13 November 1992, coll. E.E. Lindquist; 6 females, 1 male, 190 m along Surá trail, ex polypore bracket fungi on large fallen trunk, 31 October 1992, coll. V. Behan-Pelletier & E.E. Lindquist; 3 females, Surá trail “cerca puente Surá” (near Surá bridge), ex Hongo (fungus), 21 February 1995, coll. ALAS; 2 females, 150 m and 175 m along Surá trail, ex Hongo, 21February 1995, coll. ALAS; 1 female, Arboleda area, ex Hongo, 28 March 1995, coll. ALAS; 1 female, 150 m along Oriental trail, ex bracket fungi, 28 March 1995, coll. ALAS; 1 female, 200 m along Central trail, ex fungus, 18 April 1995, coll. ALAS.

The holotype female, one paratype male and several paratype females are deposited in the Instituto Nacional de Biodiversidad ( INBio) of Costa Rica, Santo Domingo de Heredia; one male and additional paratype females are deposited in the Canadian National Collection of Insects and Arachnids ( CNCI), Research Branch, Agriculture & Agri-Food Canada, Ottawa, and one male paratype and additional paratype females are deposited in the Museo de Zoología, Universidad de Navarra (MZUNAV), Pamplona, Spain.

Etymology. The specific name, armatus , is based on the Latin “ arma ”, meaning “armed” or equipped with weapons, and is intended to refer to the strong spine-like armature of setae on the tarsi of the second pair of legs.

Remarks. As noted in our previous paper describing Opilioseius grallator Lindquist & Moraza (2010), those bizarrely stilt-legged mites coexist with a remarkable variety of blattisociid and other mesostigmatic mites, including the stout-legged Fungiseius armatus , in bracket fungi. In addition to the diverse mesostigmatan fauna we noted for just one of the samples that contained O. grallator and F. armatus , three of the other eight samples with paratypes of F. armatus noted above also contained O. grallator and other of the mesostigmatans noted previously. Some of the other inhabitants include one or two equally stout-legged species of Hoploseius . Members of that genus have the apex of the fixed cheliceral digit modified as an apparent rasping tool for feeding on fungal tissue (Lindquist 1965; Walter 1998), and their adult females are known to be phoretic on drosophilid flies that frequent bracket fungi ( Lindquist 1963, 1975). Feeding habits, phoresy, and other activities have not been ascertained for F. armatus .

Adults of Fungiseius armatus present a series of character states that are derivative, relative to those of F. clavulisetis n. sp., somewhat like those of Hoploseius tenuis Lindquist (1965) relative to those of other species of Hoploseius ( Masan & Walter 2004) . Both cases concern taxa adapted to living in bracket fungi, and involve some elongation of the idiosoma, along with losses of some opisthodorsal setae and reduction in leg chaetotaxy. In H. tenuis , these derivative attributes are correlated with adaptation by all instars of this species to living within the pore tubes of bracket fungi, whereas those of other species live freely on the undersurfaces of the fungi they inhabit. No data or observations are available to address the question of whether F. armatus lives in more tightly sequestered niches in bracket fungi than does F. clavulisetus.

Figures

FIGURES 1 – 8. Fungiseius armatus n. sp., adult female: 1, gnathotectum; 2, subcapitulum; 3, corniculi, dorsal view; 4, labrum; 5, tritosternum, showing denticles at base of laciniae; 6, palpus, dorsolateral view; 7 a, detail of seta al of palpgenu; 7 b, detail of seta al of palpfemur; 8 a, chelicera, lateral view; 8 b, separate paraxial view of fixed digit.

FIGURES 9 – 14. Fungiseius armatus n. sp., adult female: 9, idiosoma, dorsal aspect with detail of peritrematal shield (arrows indicate delineated strip of dorsal shield margins bearing some of r - marginal and all S - lateral setae); 10, detail of separate views of dorsal setae denoted and lyrifissure; 11 a – b, detail of ventral view of dorsal and peritrematal shields; 12, detail of exopodal IV with peritremal poroidotaxy at level of coxa IV; 13, detail of denoted dorsal setae; 14, detail of dorsal ornamentation.

FIGURES 15 – 18. Fungiseius armatus n. sp., adult female: 15, idiosoma, ventral aspect; 16, detail of peritrematal shield, fused to exopodal strips between legs II – III and III – IV; 17, detail of sternal shielding; 18 a, b, detail of spermatheca.

FIGURES 19 – 24. Fungiseius armatus n. sp., adult female: 19 – 22, legs I – IV, excepting tarsi: 19, leg I excluding tarsus, laterodorsal view; 20, leg II, posterolateral view; 21, leg III, dorsal view; 22, leg IV, anterolateral view; 23, trochanter I, ventral view; 24, detail of denoted setae of tibia I.

FIGURES 25 – 31. Fungiseius armatus n. sp., adult female: 25, tarsus I, anterolateral view; 26, detail of apical seta on tarsus I; 27, tarsus II, posterolateral view; 28, tarsus III, dorsal view; 29, tarsus IV, dorsal view; 30, detail of ventral aspect of tarsus IV with ventral process; 31, detail of lateral aspect of tarsus IV. Abbreviation: t p, tarsal process.

FIGURES 32 – 37. Fungiseius armatus n. sp., adult male: 32, subcapitulum; 33, chelicerae, dorsolateral view; 34, chelicerae, detail of fixed digit with pilus dentilis; 35, chelicera, detail of movable digit and spermatodactyl; 36, detail of spermatodactyl; 37, idiosoma, ventral view.

FIGURES 59 – 60. Photomicrographs of adult females in dorsoventral habitus view: 59, Fungiseius armatus n. sp.; 60, Fungiseius clavulisetis n. sp.