Myrmozercon mites are highly host specific: two new species of Myrmozercon Berlese associated with sympatric Camponotus ants in southern Quintana Roo, Mexico

Diagnosis

Dorsal shield with 30–34 pairs of slightly thickened and apically blunt setae, opisthonotal setae mostly with small denticles in the distal 1/3; a wide sclerotized band of marginal striations flanking the shield dorsolaterally in female, not fused, or narrowly fused medially (Figs. 2A, 2B); band bearing 6–10 pairs of setae. Female sternal shield wide, subrectangular, narrowly fused to endopodal plates between coxae III–IV laterally. Sternal setae short; setae st4 present. Male sternitogenital shield with 6–7 pairs of setae (one ventral seta may be present or absent), st1 on lightly sclerotized area. Epigynal shield longer than wide (length/width ratio ≈ 1.8). Anal shield with moderately enlarged anterolateral projections; circum-anal setae thickened, blunt. With 23–30 pairs of setae on dorsal soft cuticle and about 20 pairs of setae on ventral soft cuticle. Metapodal shields absent in female, present in male. Deutosternal groove with 15–16 rows of 6–25 minute denticles. Palp chaetotaxy from trochanter to genu: 1-5-6; palp tibia and tarsus fused dorsally. Cheliceral digits poorly sclerotized, edentate. Female legs trochanters I–IV with 6, 5, 5, 5, femora I–IV with 14, 11, 6, 5–7 setae, genua I–IV with 13, 11, 11, 11, and tibiae I–IV with 13, 10, 10, 10 setae, respectively; basitarsus IV with 4 or 5 setae. Male with similar leg setation, but trochanter IV with 6–7 setae; setae al2 on genu and tibia I present or absent.

Description

Dorsal idiosoma (Figs. 2A–2C). Idiosoma length 875–930, width 695–820. Dorsal shield length 640–685, width 545–570; shield lightly sclerotized near margins, with reticulate ornamentation throughout; bearing 30–34 pairs of setae, setae may be absent asymmetrically, without unpaired Jx setae; setae slightly thickened, apically blunt (Fig. 2A, inset), most setae in podonotal region smooth, posteromedian setae with 0–3, and posteromarginal setae with 5–8 small denticles, opisthonotal region setae mostly with 1–10 small denticles in distal 1/3; dorsal shield setae ranging in length from 36 (j1) to 92 (J3) (Figs. 2A, S3). Shield with 14 pairs of pore-like structures, all of them resemble subcircular poroids; id1 absent. Dorsal shield flanked by wide sclerotized bands of marginal striations, starting anteriorly at level of setae s2; bands not fused (Fig. 2A), or narrowly fused posteromedially (Fig. 2B); bearing 6–10 pairs of setae similar in shape to dorsal shield setae, 50–80 long. Posterior opisthonotum with soft cuticle bearing 23–30 pairs of setae, similar in shape to other dorsal setae, 50–80 long.

Ventral idiosoma (Figs. 3, S4). Tritosternal base columnar, short, 24–26 long, 36–42 wide at base and 24–28 at top; laciniae length 104–130 free, 11–13 fused at base, with sparse, very short barbs in distal half. Sternal shield wide, subrectangular, 135–150 long, 201–226 wide at level of setae st2, 290–298 at broadest width between coxae II–III; shield narrowly fused with endopodal elements between coxae III–IV; anterior margin of shield bilobed, posterior margin eroded and irregular; a narrow anterior area of shield surface with reticulate ornamentation. Sternal shield with three pairs of smooth and short sternal setae, setae shorter than half the distance between their insertions, st1 23–27, st2 28–34, st3 31–41 long; with two pairs of small slit-like poroids, iv1 behind setae st1, iv2 between setae st2–3. Setae st4 (34–44 long) and adjacent poroids (iv3) inserted on soft cuticle. Epigynal shield longer than wide, 380–390 long, 190–230 wide at level of genital setae (st5), moderately wider (210–242) past setae st5. Setae st5 inserted on lateral margins of epigynal shield (right margin of shield in one specimen eroded and adjacent seta st5 off the shield), 39–45 long. Anal shield terminal; anterolateral angles of shield only slightly developed; shield 190–212 wide at broadest level, 125–155 long; circum-anal setae thick, and apically blunt, with or without a few subapical short denticles; paranal setae 52–59, postanal seta 58–65 long; cribrum well-developed, extending anteriorly to level of paranal setae. Peritremes short, extending from stigmata at mid-level of coxae IV to mid-level of coxae III. Peritrematal shields narrow, not developed posteriorly, narrowly fused to dorsal shield anteriorly, pore-like structures on the shields not observed. Opisthosomal soft cuticle usually with one pair of narrow and short platelets flanking posterior margins of epigynal shield, sometimes with closer platelets partially fused with the shield, rarely without platelets; parapodal plates narrow; metapodal plates absent; seven pairs of poroids, including iv5 and ivp, and about 20 pairs of setae; 8-10 pairs of pre-anal setae smooth, marginal setae longer, thicker, and denticulate (similar to dorsal shield setae); length ranging from 31 to 77. Insemination ducts opening on posterior margin of coxae III.

Gnathosoma (Figs. 2D, 4A, 4C, 4F, S5). Gnathotectum subtriangular, with smooth lateral margins and regular or irregular rounded tip. Supralabral process short and undivided apically, without apicoventral projection (Fig. 2D). Hypostome with paired internal malae with moderately narrow anterior projections, with smooth margins, bearing 3–5 small narrow denticles on posterolateral margins, almost as long as corniculi. Corniculi membranous, lightly sclerotized laterally (Fig. 4A). Labrum blade-like, with short and dense fringed margins, anteriorly extending almost to level of corniculi. Hypostomal setae smooth, pointed, h1 22–26, h2 24–26, h3 39–44, sc 28–30 long. Deutosternal groove moderately wide, lateral ridges flanking 15–16 rows of about 10 (basal rows) to 25 minute denticles, and an anterior smooth ridge. Second segment of chelicera narrow, 163–166 long; cheliceral digits edentate, fixed digit 50–54 long, pilus dentilis vestigial; movable digit 75–77 long, partially membranous; dorsal cheliceral seta, dorsal poroid and slit-like lateral poroid present (Fig. 4C). Palp 161–170 long, palp chaetotaxy from trochanter to genu: 1-5-6, tibia and tarsus fused dorsally, palp apotele two tined (Fig. 4F).

Legs (Fig. 5). All legs with well-developed ambulacra, pulvilli large, claws not developed, pretarsal operculae well-developed, two-tined apically (Figs. 5B–5D, inset). Lengths of legs I –IV: 1135–1160, 710–740, 825–860, and 990–1035, respectively. Leg chaetotaxy as in Table 1; femur IV with 5, 6, or 7 setae (one seta lost or added relative to the “standard” pattern for Laelapidae), basitarsus IV occasionally with an additional seta bringing the total number to 5 (both states observed in one specimen) (Fig. 5D). Leg setae smooth, setae on coxae I–IV and several setae on trochanters and tarsi I–IV pointed, other setae mostly blunt; setae ad and av on trochanter I, setae ad1–2, pd1, av1–2, pv2–3 on femur I, setae ad1 and pd1 on femur II, setae pd and ad on trochanter III, setae ad, pd1–2, and seta al on femur III, setae al and ad on trochanter IV, setae al, ad1–2, av, pd1 on femur IV thickened; several setae on genu and tibia I, genu II, genua and tibiae III–IV slightly thickened; legs without elongate seta.

Dorsal idiosoma (Fig. 6A). Dorsal shield length 597, width 545, bearing 34 pairs of setae, j1 shortest (28), J5 longest (74), length of other setae 38–71. Dorsal soft cuticle with 18–22 pairs of setae. Wide sclerotized band of marginal striations absent. Other characters similar to female.

Ventral idiosoma (Fig. 6B). Tritosternal base 21 long, 35 wide at base and 23 wide at apex, laciniae 101 free and fused for 6 µm. Sternitogenital shield length 411, width 163 at level of st2, 274 at broadest level behind coxae IV; anterior area of shield lightly sclerotized, bearing setae st1, 27 long, apically pointed; well-sclerotized area of shield with reticulate surface ornamentation, bearing st2–5 (27–31 long), and three ventral setae: two on left and one on right side of shield, 24 –30 long, setae st1–4 apically pointed, others blunt; shield with four pairs of poroids, iv1–3 small and slit-like, iv5 round, iv1 on anterior margin of well-sclerotized area of shield. Anal shield terminal, length 121, width 167, circum-anal setae thickened, apically rounded; postanal seta (47) slightly longer than paranals (43). Opisthogastral soft cuticle with a pair of lightly sclerotized metapodal shields, and about 24 pairs of blunt setae; posterolateral setae with small denticles in distal 1/3.

Gnathosoma. Hypostomal setae length: h1 21, h2 20, h3 35, sc 27. Deutosternal groove with 16 rows of multiple small denticles, and an anterior smooth ridge. Second segment of chelicera 157 long; cheliceral digits edentate, fixed digit lightly sclerotized, 56 long; movable digit, including straight spermatodactyl, well sclerotized, 120 long (Fig. 4D). Palp 155 long. Other structures similar to female.

Legs. Length of legs I–IV 990, 593, 733 and 855, and pretarsi I–IV 77, 62, 63 and 65, respectively. Pretarsal claws I–IV not developed, but pulvilli of all legs, and pretarsal operculae II–IV (apically divided into two tines) well-developed. Chaetotaxy as in female (Table 1) with the following exceptions: left trochanter IV with 7 and right segment with 6 setae; seta al2 on genu and tibia I absent on one side of the body, present on the other; right basitarsus IV with 4 setae, left one with 5. Setal shapes as in female.

Dorsal idiosoma. Dorsal shield length 590, width 450, shield lightly sclerotized on margins; with 32 pairs of slightly thickened setae, setae smooth or with small denticles in apical third, blunt; length of setae ranging from 20–56, j1 shortest and Z5 longest. Wide sclerotized band of marginal striations absent. Other characters similar to female.

Ventral idiosoma. Tritosternal base 16 long, 28 wide at base and 22 at apex, laciniae 84 free and fused for 22 µm. Sternal shield lightly sclerotized, with faint reticulate ornamentation, margins of shield not distinct, setae st1–3 (24–28) and poroids iv1–3 on moderately sclerotized margins of shield, st4 (24) and st5 (20) and iv4 on unsclerotized margins of shield. Anal shield terminal, lightly sclerotized, anterolateral projections of shield not developed. Other characters as in female.

Gnathosoma (Figs. 4B, 4E) Hypostomal setae length: h1 24, h2 20–21, h3 36–37, sc 27. Deutosternal groove with 16 rows of denticles, basal row with 2 denticles, second row with 6, third row with 9, and others with about 12 to 25 smaller denticles, median rows wider, with an anterior smooth ridge (Fig. 4B). Second segment of chelicera 150 long; cheliceral digits edentate, movable and fixed digits 66 and 46 long, respectively; arthrodial brush with a row of lateral denticles (Fig. 4E). Palp 168 long. Other structures as in female.

Legs. Lengths of legs I–IV: 848, 595, 718, and 824, respectively. Leg chaetotaxy as in female (Table 1) with the following exceptions: femora IV with 6 setae (no variability); basitarsi IV with 4 setae (no variability). Setal shapes as in female.

Larva

This instar was collected but the available specimen was in poor condition and is therefore not described.

Type depository

Holotype female deposited at Colección Nacional de Ácaros, Instituto de Biología, UNAM, Mexico (CNAC 012527). Paratypes at OSAL and ECO-CH-AR.

Material examined

Mexico, Quintana Roo, Laguna Guerrero, 8 m asl [18.6920, -88.2615], coll. Pérez-Lachaud, G., 1-Aug-2021, in a colony of C. atriceps (Hymenoptera: Formicidae) nesting in a dead branch of a Hibiscus shrub, 1-F, holotype, CNAC 012527; same locality, collector, collection date, and source, 1-F, OSAL 159521; 1-F, OSAL 159522; 1-F, OSAL 159523; 1-M, OSAL 159520; 1-DN, OSAL 159525; same host species, locality and collector, 17-Jul-2022, in a trap-nest, 3-F 1-M, in 75% ethanol, OSAL 160580; 15-Jan-2022, same host species, locality and collector, nest in hanging dry branch, 2-F, in 75% ethanol, OSAL 160581; 10-Aug-2022, in a bamboo trap-nest, 2-F 1-DN, in 75% ethanol, OSAL 160582; same host species, locality and collector, 15-Aug-2021, in a trap-nest, 3 adults of unknown sex, ECO-CH-AR AA3479-AA3481.

Additional material: Mexico, Chiapas, Huixtla, 52 m asl, coll. Lachaud, J.-P., 6-Sep-2005, in a colony of C. atriceps in mango plantation, 2-F, OSAL 161616–161617.

Etymology

The species epithet “serratus” was chosen on the basis of the shape of most setae in the opisthonotal region of the dorsal shield.

Notes on the species

With a combination of characters, including the long legs with hypertrichous setae, the reticulate dorsal shield, and the subrectangular sternal shield, M. serratus sp. nov. is a member of the species group designated Myrmozercon sensu lato by Joharchi, Babaeian & Seeman (2015). Within this group, the newly described species is most similar to M. antennophoroides (Berlese) (Berlese, 1903), M. hunteri Joharchi, Babaeian & Seeman (Joharchi, Babaeian & Seeman, 2015), and M. patagonicus Trach & Khaustov (Trach & Khaustov, 2018) by the presence of 30–34 pairs of setae on the dorsal shield and a subrectangular sternal shield. Myrmozercon serratus sp. nov. differs from M. antennophoroides by the presence of only one pair of setae on the epigynal shield (two pairs in M. antennophoroides), legs I much longer than dorsal shield, their length ratio ≈ 1.7 (legs I shorter in M. antennophoroides, legs I/dorsal shield length ratio ≈ 1.37), and gnathotectum subtriangular, but no elongate in the new species (subtriangular and elongate in M. antennophoroides). The new species can be distinguished from M. hunteri by the presence of 6 setae on trochanter I and 13 setae on tibiae I (5 and 10 setae, respectively, in M. hunteri), presence of simple setae with pointed tips on the legs (most setae on legs with club-like tip in M. hunteri), and presence of a wide sclerotized band of marginal striations surrounding the dorsal shield (absent in M. hunteri). Myrmozercon patagonicus can be differentiated from M. serratus sp. nov. by the presence of 19–21 rows of denticles in the deutosternal groove (15–16 rows in M. serratus sp. nov.), presence of metapodal platelets (absent in M. serratus sp. nov.), 4 setae on palp femur (5 in the new species), and also 14 setae on genua I, 7–8 setae on femora III and 8 setae on femora IV (13, 6, and 6 setae, respectively, in M. serratus sp. nov.).

Diagnosis

Dorsal shield with 27–31 pairs of slightly thickened and apically spatulate setae; wide sclerotized band of marginal striations well-developed in female (less developed in male), surrounding the shield laterally and broadly fused posteromedially; band bearing 10–12 pairs of setae. Female sternal shield wide, moderately narrow; with relatively long sternal setae, st2–3 as long as the distance between their insertions, st1 slightly shorter than st1–2 interval. Female sternal shield adjacent to, but not fused to, endopodals between coxae III–IV. Setae st4 absent. Male sternitogenital and deutonymphal sternal shield bear five and four pairs of setae, respectively. Epigynal shield large and wide, almost as long as wide (length/width ratio ≈ 0.9). Anal shield wide, anterolateral edges well-developed, circum-anal setae thickened, apically spatulate. With 7–10 pairs of setae on dorsal and 14–16 pairs of setae on ventral soft cuticle. Metapodal shields present. Deutosternal groove with 18–19 rows in female and deutonymph, and 15 rows in male, each row with multiple denticles; palp chaetotaxy from trochanter to genu: 1-4-5. Cheliceral digits poorly sclerotized, edentate; spermatodactyl sickle-shaped. Female femora I–IV with 13, 10, 6–7, 8–9 setae, genua I–IV with 13, 11, 11, 11, and tibiae I–IV with 13, 10, 10, 10 setae, respectively. Leg setae, especially dorsal setae on trochanter to tibia, apically spatulate.

Description

Dorsal idiosoma (Fig. 7). Idiosoma 645–770 long, 590–620 wide. Dorsal shield with a reticulate ornamentation throughout; 570–650 long, 535–555 wide; bearing 27–31 pairs of setae, setae j1 shortest (26–28), slightly thickened with blunt tip, other setae 29–58 long, thickened, with spatulate tip (Fig. 7B, inset), mostly smooth, rarely with small lateral denticles behind spatulate tip. Dorsal shield with 10 pairs of pore-like structures, id1 absent. Dorsal shield flanked with well-developed sclerotized band of marginal striations, bearing 10–12 pairs of setae similar in shape to those on dorsal shield, 35–45 long. Posterolateral membranous area of dorsal idiosoma with 7–10 pairs of setae, similar in length and shape to setae on sclerotized band of marginal striations.

Ventral idiosoma (Figs. 8, 9A–9C). Tritosternum with a short columnar base, 31–33 long, 35–39 wide at base and 26–28 wide at apex; laciniae free, total length 88–99, sclerotized near the base for 12–14 µm, with 1–12 minute ventral spicules and smooth hyaline margins (Figs. 8A, 9A, arrows). Sternal shield wide, 70–85 long, 187–194 wide at level of setae st2, 254–256 at greatest width between coxae II–III; anterior margin bilobed, posterior margin eroded, irregularly concave, sometimes with a small median projection, up to 15 long; posterolateral margins of shield adjacent to, but not fused to, endopodal elements between coxae III–IV. Anterior and anterolateral regions of sternal shield with reticulate ornamentation, median reticulation faint. Sternal shield with three pairs of smooth and moderately long sternal setae, st1 43–47, st2–3 45–48 long, and two pairs of slit-like poroids. Setae st4 and associated poroids (iv3) absent. Epigynal shield wide, expanded behind coxae IV, with irregularly convex posterior margin; surface reticulate; 278–286 long, 315–319 wide at broadest level beyond setae st5 insertion; setae st5 on lateral margins of shield, 36–46 long. Anal shield with well-developed anterolateral projections; anterior margin finely convex and lightly sclerotized; 95–115 long and 205–220 wide at broadest level; cribrum well-developed; circum-anal setae thick, and apically spatulate, paranal setae (52–57) slightly longer than postanal (48–51) (Fig. 9C). Peritrematal shields narrow, not developed beyond stigmata, narrowly extended anteriorly and fused to dorsal shield; pore-like structures invisible in specimens examined. Peritremes short, extending anteriorly from stigmata at posterior level of coxae IV to anterior level of coxae IV or posterior level of coxae III. Opisthogastral soft cuticle with one pair of narrow parapodal plates, 1–3 pairs of moderately small and narrow metapodal platelets, 1–2 minute paragenital platelets lateral to Jv1; with 14–16 pairs of setae, Jv1 (30–35) moderately slender with blunt apex, Jv2–4 and Zv2 slightly thickened (32–42), others thickened with spatulate tip (32–55); with six pairs of poroids, including iv5 (behind st5 level), ivp and four pairs of ivo (Fig. 8A). Insemination ducts opening on posterior margin of coxae III (Fig. 9B).

Gnathosoma (Figs. 9D, 10A, 10B, 10D, 10G). Gnathotectum subtriangular, with smooth lateral margins and regular or irregular rounded tip, connected to dorsum of gnathosoma by a narrow neck (Figs. 9D, 10A). Supralabral process subtriangular, short (Fig. 10A, sp); labrum blade-like, with fringed margins, extending slightly beyond anterior margin of gnathotectum (Fig. 10A, lb). Hypostome with paired internal malae with moderately narrow and smooth anterior projections, not extending to anterior level of corniculi; corniculi membranous. Hypostomal setae smooth, h1 11–14, h2 21–23, h3 38–41, sc 31–33. Deutosternal groove wide, lateral ridges flanking 18–19 rows of multiple denticles, arranged between smooth anterior and posterior ridges; denticles in most rows subequal in size, except in anteriormost row which has larger denticles (Fig. 10B). Second segment of chelicera narrow, 113–116 long; cheliceral digits edentate, fixed digit 36–38 long, pilus dentilis vestigial; movable digit 51–53 long, partially membranous; dorsal cheliceral seta, dorsal and lateral poroids present (Fig. 10D). Palp 104–108 long, palp chaetotaxy from trochanter to genu: 1-4-5, tibia and tarsus fused dorsally, with 23 setae, palp tarsus apotele two-tined (Fig. 10G).

Legs (Fig. 11). All legs with pretarsus and well-developed ambulacrum, pretarsal operculae II–IV well developed, divided into 4–5 apical branches. Lengths of legs I–IV: 780–800, 555–570, 615–635, 660–675. Leg chaetotaxy as in Table 2. Leg setae smooth, setae on coxae I–IV and several setae on trochanters and telotarsi I–IV slender and pointed, most other leg setae apically blunt or spatulate, slender or slightly thickened, except setae ad on trochanter I, setae ad1–3 and pd1 on femur I (Fig. 11A), setae ad1–2 and ad1 on femur II (Fig. 11B), setae al, ad1–2 and pd1 on femur III (Fig. 11C), and setae al, ad1–2 and pd1 on femur IV (Fig. 11D) which are thickened with spatulate tips; legs without elongate setae.

Dorsal idiosoma. Idiosoma of well sclerotized specimen 649 long, 530 wide, that of less sclerotized male 550 long, 477 wide. Dorsal shield with reticulate ornamentation throughout; length and width of shield in well-sclerotized specimen 587 and 530, respectively, not measured in less sclerotized specimen because shield margins were not detected; shield bearing 32 (26 in less sclerotized specimen) pairs of setae, 20–42 long, with 14 pairs of pore-like structures. Wide sclerotized band of marginal striations distinct in well-sclerotized specimen, with two pairs of setae, 32–35 long. Opisthosomal soft cuticle in well-sclerotized specimen devoid of setae, with four pairs of setae in less sclerotized specimen. Other characters similar to female.

Ventral idiosoma (Fig. 12A). Tritosternal base 10–12 long, 28–30 wide at base and 22 wide at apex; laciniae free, total length 80–86, sclerotized near the base for 10–12 µm, without ventral minute spicules, other characters similar to female. Sternitogenital shield wide, extending well beyond coxae IV, widened behind coxae IV; reticulate over entire surface, area between tritosternal base and anterior margin of well-sclerotized region of sternitogenital shield poorly sclerotized, bearing setae st1; posterior margin of shield irregularly convex, shield 355–381 long, 165–180 wide at level of setae st2, 283–303 wide at broadest level beyond coxae IV. Setae st1–3 slender, with pointed apex (whip-like), 34–37 long, st5 with rounded tip (26–33), Jv1 and Zv1 (19–22) with lightly spatulate tip; with three pairs of poroids, iv1–2 small and slit-like, iv5 round, iv3 absent. Anal shield with slightly convex anterior margin and anterolateral projections, 102–105 long and 162–180 wide at broadest level; paranal setae 35–43, postanal 43–48 long. Opisthogastral soft cuticle with 3–5 narrow metapodal platelets; cuticle bearing 3–5 pairs of setae (26–30) with spatulate apex and 5 pairs of poroids.

Gnathosoma (Fig. 10E). Gnathotectum similar to female. Hypostome, corniculi, labrum and supralabral process as in female. Hypostomal setae h1 10–11, h2 15–18, h3 32–38, sc 23–27 long. Deutosternal groove wide, with 16 rows of multiple small denticles. Second segment of chelicera narrow, 120–128 long; cheliceral digits edentate, fixed digit 41–46 long, movable digit, including sickle-shaped spermatodactyl, 78–81 long (Fig. 10E). Palp 110–114 long, palp chaetotaxy similar to female. Other characters as in female.

Legs. Lengths of legs I–IV: 700–710, 485–515, 545–560, 575–605. Leg chaetotaxy as in female (Table 2) with the following exceptions: tibia I occasionally lacking seta av2; femur II on one side of one specimen with only 9 (instead of 10) setae; tibia III occasionally with an extra seta (11 instead of 10 total); femur IV never with ninth seta. Setal shapes as in female.

Dorsal idiosoma. Idiosoma 588 long, 498 wide. Dorsal shield 495 long, 431 wide, with a reticulate ornamentation throughout; bearing 28 pairs of thickened setae with spatulate apex, setae mostly smooth, rarely with lateral small denticles (e.g., in J4, J5, and Z5); 24–38 long, j1 shortest, Z5 longest. Wide sclerotized band of marginal striations absent. With about 15–20 pairs of setae on opisthosomal soft cuticle, similar in shape to those on dorsal shield, 19–28 long. Other characters similar to female.

Ventral idiosoma (Fig. 12B). Tritosternal base 10 long, 30 wide at base and 22 at apex; laciniae with smooth membranous margins, 95–99 free, 6 fused at base, without ventral minute spicules. Sternal shield wide, with reticulate surface ornamentation; 316 long, 152 wide at level of setae st2, 241 at broadest level behind coxae IV. Sternal shield with four pairs of smooth setae, st1 36, st2–3 39 long, with pointed apex, st5 20 long, blunt; with three pairs of small slit-like poroids iv1–2, iv5. Posterior margin of sternal shield irregularly convex. Anal shield terminal, with anterolateral projections, 120 long, 167 wide at broadest level; circum-anal setae thick and apically spatulate, paranal setae 44 and 47 and postanal seta 38 long. Opisthogastral soft cuticle with two pairs of small metapodal platelets, seven pairs of poroids (including iv5, ivp, idR3 and four pairs of ivo), and 14–18 pairs of setae: Jv1 (26) narrow and blunt, Jv2 (23), Jv3 (22), and Zv1 (26) slightly thickened with spatulate apex, 10–14 additional pairs of thickened and moderately short (20–26) setae with spatulate apex.

Gnathosoma (Figs. 10C, 10F). Gnathotectum subtriangular, with irregular and smooth anterior margin and rounded apex. Hypostome, internal malae, labrum and supralabral process similar to female (Fig. 10C). Corniculi wide, mainly membranous, but with short horn-like sclerotized tips. Hypostomal setae smooth, sharp, h1 11, h2 18, h3 40, sc 28 long. Deutosternal groove moderately wide, lateral ridges flanking 18 rows of multiple small denticles, each row with 12–18 denticles, with smooth anterior (inverse V-shaped) and posterior (concave) ridges. Cheliceral digits poorly sclerotized, edentate, second segment of chelicera 116 long, fixed digit 35 long, movable digit 52 long, arthrodial brush with a row of denticles, extending laterally to venter, ventral denticles largest; dorsal cheliceral seta well developed (Fig. 10F). Palp 104 long, palp chaetotaxy from trochanter to tarsus: 1-4-5, palp apotele two-tined. Other characters similar to female.

Legs. Lengths of legs I–IV: 710, 526, 579, 612. Leg chaetotaxy as in female (Table 2) with the following exceptions: right leg tibia I with 14, not 13, setae (pl3 added); both legs with 7 setae on femora II (not 6 or 7); basitarsus IV of one leg with 5 (not 4) setae. Setal shapes as in female.

Larva

This instar was collected but specimens were in poor condition and only a few aspects can be described. Except for sternal (10–18 long, needle-like), circum-anal setae (paranals 8–9, postanal 12 long, cone-like), and most dorsal setae on telotarsus I, all remaining setae minute (3–5) or vestigial. No distinct shields observed.

Type depository

Holotype female deposited at Colección Nacional de Ácaros, Instituto de Biología, UNAM, Mexico (CNAC 012528). Paratypes at OSAL and ECO-CH-AR.

Material examined

Mexico, Quintana Roo, Laguna Guerrero, 8 m asl [18.6920, -88.2615], coll. Pérez-Lachaud G., 29-July-2020, in a colony of C. rectangularis established in a trap-nest (Hymenoptera: Formicidae), 1-F, holotype, CNAC 012528; same locality, collector, collection date, and source, 1-M, OSAL 159512; 1-DN, OSAL 159513; 1-DN, OSAL 159514; 1-F; OSAL 159515; 1-F, OSAL 159516; 1-M, OSAL 159517; 1-F, OSAL 159518; 1-F, OSAL 159519; 1-F, ECO-CH-AR AA3477; 1-F, ECO-CH-AR AA3478; same locality, collector, 20-September-2020, C. rectangularis, colony in a bamboo trap-nest, 2-F, in 75% ethanol, OSAL 160583.

Etymology

The species epithet “spatulatus” was chosen on the basis of the shape of most dorsal and opisthogastral setae.

Notes on the species

Myrmozercon spatulatus sp. nov. also belongs in Myrmozercon sensu lato especially based on the long legs with hypertrichous setae and the reticulate dorsal shield. Within this species group, the absence of metasternal setae is similar to M. iainkayi Walter (Walter, 2003) and M. beardae Shaw & Seeman (Shaw & Seeman, 2009). Myrmozercon iainkayi can be differentiated by several characters, e.g., the presence of a hypertrichous dorsal shield with simple and short setae (M. spatulatus sp. nov. has 27–31 pairs of moderately long and spatulate setae), coxae I–IV with 6, 6, 6, and 4 setae respectively (with standard set of coxal setae in M. spatulatus sp. nov.), and a horseshoe-shaped sternal shield (only slightly concave posteriorly in the new species). Myrmozercon spatulatus sp. nov. differs from M. beardae by the different shape of the sternal, epigynal, and anal shields, in addition to characters like the shape and number of setae on the dorsal shield (23–25 pairs of moderately short and simple setae in M. beardae, 27–31 pairs of moderately long and spatulate setae in M. spatulatus sp. nov.), and different setation on coxa IV (2 setae in M. beardae, 1 in M. spatulatus sp. nov.).