Lasioseius cassidini, Moraza & Lindquist, 2018

Moraza, Maria L. & Lindquist, Evert E., 2018, A new species-group with new species of the genus Lasioseius (Acari: Mesostigmata: Blattisociidae) associated with Neotropical hispine beetles in furled leaves ofHeliconia, Acarologia 58 (1), pp. 62-98 : 69-74

Lasioseius cassidini n. sp. ( Figures 1 , 2 , 11A , 12C , 13 A-B, 14A)

Zoobank: EB77E489-1EB6-4120-9375-44E765ABEFF3

Diagnosis — Adult female: Sternal shield weakly lineate along lateral margins, smooth medially, its posterolateral corners not emarginated; poroids iv3 alone, on soft cuticle, setae st4 on tiny metasternal platelets; epigynal shield partially reticulated, its lateral margins concave, narrowed anterior to setae st5; ventrianal shield with posterolateral margins on either side of anus divergent anteriorly, and with four pairs of opisthogastric setae, JV1 on shield; metapodal plates well separated on each side. Dorsal setae r6 on edge of dorsal shield; Z5, S5 attenuated like adjacent setae. Adult male: Dorsal shield setae S5 dimorphically less attenuated. Sternitigenital shield incompletely reticulated, nearly smooth medially. Tibiae III-IV with setae (v) dimorphically spinelike, blunt; genu IV av similarly so. Adult attributes: Gnathotectum anterior margin truncate, irregularly denticulate. Fixed chela with file of ca 20 teeth in female, ca 18 in male. Sternal setae st1 inserted in weakly sclerotized presternal region. Tarsi II-IV with ventral apical process bluntly pointed, smooth apically; tarsi II-III with seta av-1 slightly longer than pv-1; pretarsi III-IV with anterior paradactylus asymmetrically elongate, twice as long as claws; tarsus IV with distal seta av-1 clearly larger, thicker than adjacent setae.

Description

Idiosomatic dorsum — Adult female. Dorsal shield 703 – 757 long, 375 – 410 wide at level of r3, 428 – 477 wide at r6 (n=9), lightly reticulated over entire surface, without puncta behind level of setae Z4; shield with 38 pairs of setae generally similar in size and acutely pointed form, J1-J4 about as long or slightly longer than longitudinal intervals between their bases; J5 minute, barbed (8 – 12): j1, j2 (45 – 60), j3 (67 – 76), j4 (50 – 57), j5 (56 – 62), j6 (70 – 77), z1 (37 – 42), z2 (56 – 65), z3 (60 – 68), z4 (72 – 77), z5 (52 – 62), z6 (62 – 74); s1 (58 – 75), s2 (65 – 75), s3 (70 – 75), s4 (70 – 80), s5 (82 – 92), s6 (85 – 96), r2 (62 – 74), r3 erect (60 – 67), r4 (75 – 80), r5 (75 – 82), r6 (70 – 79), J1 (65 – 75), J2 (68 – 77), J3 (67 – 82), J4 (70 – 75), Z1, Z2 (92 – 103), Z3 (100 – 112), Z4 (107 – 122), Z5 (93 – 110), S1 (77 – 95), S2, S3 (88 – 103), S4 (97 – 110), S5 (82 – 105). Lateral soft cuticle with seven pairs of smooth setae, including R1-R3 (48 – 62), R4-R6 (42 – 53) and ZV5 (47 – 55) posteriorly ( Figs. 1A, B, C ).

Adult male. Dorsal shield 493 – 610 long, 315 – 342 wide at level of setae r3, 345 – 367 wide at r6 (n = 8); shield ornamentation, complement of pore-like structures and setation as in female; posterolateral setae attenuated as in female. Setae j1 (40 – 50), j2 (35 – 47), j3 (50 – 60), j4 (38 – 45), j5 (43 – 47), j6 (53 – 62), z1 (28 – 38), z2, z3 (43 – 55), z4 (52 – 62), z5 (40 – 45), z6 (48 – 55), s1 (47 – 57), s2-s4 (50 – 65), s5, s6 (60 – 75), r2 (50 – 60), r3 erect (38 – 55), r4, r5 (53 – 67), r6 (45 – 57), J1, J2 (43 – 55), J3 (50 – 62), J4 (40 – 47), J5 (5 – 9), Z1 (63 – 80), Z2 (65 – 92), Z3 (66 – 98), Z5 (61 – 77), S1 (54 – 72), S2 (55 – 77), S3, S4 (60 – 78), S5 (50 – 70), Z4 longest (80 – 102) of opisthonotal setae. Lateral soft cuticle with five or six pairs of R- setae (33 – 48) ( Fig. 2A ), R2 sometimes on small platelet ( Fig. 2E ).

Idiosomatic venter — Adult female. Tritosternum base sometimes biarticulate, 38 – 43 long and 20 – 22 wide at its base, with paired laciniae fused for about 22 – 25 of entire length (122 – 135). Presternal region with circumscribed pair of weakly granulated, lineated areas, flanked anteriorly by a pair of weak or distinct narrow strips on either side of tritosternal base, and with setae st1 (33 – 37) inserted on this region, anterior to sternal shield. Sternal shield 127 – 135 long from anterior margin at transverse level with poroids iv1 to slightly concave posterior margin, 125 – 136 wide, weakly lineated along lateral margins, smooth medially; sternal setae st2, st3 of similar length (30 – 37). Sternal poroids iv3 alone on soft cuticle, setae st4 (28 – 35) on tiny metasternal platelets (13 – 15 x 8 – 11). Endopodal strips narrow between coxae III and IV. Epigynal shield sparsely reticulated, its broadly rounded hyaline anterior margin not overlapping posterior edge of sternal shield, its lateral margins slightly concave, narrowed anterior to setae st5 (38 – 47), and its posterolateral corners emarginated behind st5; shield 208 – 225 long, 118 – 137 at widest level at posterior rounded corners, 80 – 87 at narrowest width between legs IV. Opisthosomatic venter with two pairs of well separated metapodal platelets, primary pair elongate-oval, 33 – 40 long, 15 – 19 wide, secondary pair small, 10 – 16 by 5 – 7. Ventrianal shield inversely subtriangular with angulose or rounded anterior corners, with posterolateral margins on either side of anus divergent anteriorly; surface entirely reticulate, and punctate on either side of postanal seta; shield wider (293 – 337) than long (212 – 232), width at anal level (130 – 155); poroids ivo2 on shield anterior edge behind setae ZV1; gland pore gv3 on or off shield posterior to anal opening; shield with four pairs of ventral setae: JV1 (37 – 42), JV2 (43 – 50), JV3 (44 – 55), ZV2 (35 – 48); with paranal setae (21 – 27) shorter than postanal seta (43 – 65). Soft cuticle with five pairs of simple opisthogastric setae, ZV1 (35 – 44) anterior to ventrianal shield, ZV3 (33 – 43), ZV4 (37 – 44), JV5 (55 – 67) flanking the shield, and ZV5 aligned behind R6; three pairs of poroids on soft cuticle. Peritrematal-exopodal shield with lines extending from stigma into rounded posterior margin ( Fig. 1C ); peritreme extending to level between setae s1 and z1 ( Fig. 1A ). Spermathecal apparatus with cup-like calyx 28 – 29 long to embolus, 30 – 31 including it ( Fig. 1F ).

Adult male. Tritosternum much as in female, but with base biarticulate, longer (20 – 32) than wide (15 – 19), and with laciniae fused for only about 10 – 15 of entire length (88 – 107). Presternal region faintly sclerotized, with a pair of distinct narrow strips on either side of tritosternal base, and with setae st1 inserted on this region on either side of genital opening. Sternitigenital shield length 225 – 267, narrowest widths 88 – 113 at level between coxae II, 77 – 95 between coxae III, 58 – 87 between coxae IV; shield slightly lineated along lateral margins and posteriorly between coxae IV, unornamented medially, with endopodal apices freely acuminate beside coxae IV; setae st1 (28 – 32) and st5 (28 – 37) longer, st2-st4 (17 – 26); poroids iv3 sometimes hardly discernible flanking faint pair of pits ( Fig. 2A ). Ventrianal shield well reticulated and with punctate fields in anal region as in female, its convex anterior margin sometimes excised near apices of exopodal strips behind coxae IV, and posterolateral margins slightly constricted in anal region; shield much wider (278 – 337) than long (170 – 228, including cribrum ca. 8 – 11 long, 58 – 65 wide); shield with six or usually seven pairs of opisthogastric setae, JV5 asymmetrically on or off shield ( Figs. 1A, B ); JV1 and ZV1 (23 – 32), JV2 (28 – 37), ZV2 (28 – 32), JV3 (28 – 42), ZV3 (23 – 30), JV5 (39 – 50); postanal seta smooth (39 – 47), about twice as long as paranal setae (15 – 22). Soft opisthogastric cuticle with two pairs of setae, ZV4 (26 – 30), and ZV5 (30 – 42) aligned behind R6, one pair of lyrifissures, ivp.

Gnathosoma — Adult female. Gnathotectum anterior margin broadly truncate, with two lateral smooth prongs and serrate medial edge ( Fig. 1D ). Cheliceral shaft, excluding basal section, 160 – 173 long, with slender digits; dorsal seta blunt (13 – 14); fixed digit with tiny offset subapical tooth and row of 18-22 very fine teeth ( Fig. 1G ), pilus dentilus minute, at level between 4 th- 5 th apical teeth; movable digit (71 – 75) tridentate ( Fig. 1H ). Subcapitulum rows of deutosternal denticles progressively slightly wider posteriorly, each with numerous (ca 30-35) fine denticles, 6th and sometimes 7th widest and with ca 40-45 and 35-40 teeth, respectively ( Fig. 1E ); subcapitular setae hp1 (40 – 45) slightly shorter than hp3 (48 – 52) and capitular seta pc (43 – 52), hp3 much longer than hp2 (23 – 27). Palp length (195 – 212); apical margin of palptrochanter with a single spine anterolaterally; palptrochanter setae dissimilar in length, v1 48 – 52, v2 38 – 42.

Adult male. Gnathotectum as in female ( Fig. 2C ). Cheliceral shaft, excluding short basal section 105 – 130 long; fixed digit with offset subapical tooth followed by minute pilus dentilis inserted on small angular protrusion and row of 11-16 small teeth ( Fig. 2H ); movable digit (40 – 45) unidentate; spermatodactyl 45 – 54 long, 8 – 9 wide at medial region, extending anteriorly 28 – 37 beyond apex of digit, with narrowed neck and small bifid head apically ( Figs. 2F, G ). Corniculi more widely spaced but not more arched than in female, 33 – 37 long, and flanked medially by pair of short (7-10) spiculate processes ( Figs 2D , 11A ); internal malae and labrum as in female. Subcapitulum with seven rows of deutosternal denticles much as in female, sixth and seventh rows slightly widest; hypostomatic setae hp1 (28 – 32) similarly as long as pc (25 – 37), hp3 usually longest (30 – 50), hp2 (12 – 20). Palpi (length 145 – 187) similar in structure, form of setae as in female; palptrochanter with inner seta longer (30 – 44) than outer seta (17 – 32) but not markedly whip-like.

Legs — Adult female. Legs I (707 – 755) about as long as legs IV (715 – 750), and about as long as dorsal shield; other leg lengths (excluding pretarsi): II (565 – 600), III (587 – 615). Leg I pretarsus with biarticulate shaft (38 – 42 to base of claws), tarsus (187 – 205) about 1.6 longer than tibia; other length ratios, femur (135 – 147): genu (112 – 118): tibia (117 – 125) about 1.15: 0.95: 1.0. Legs II-IV with tarsus/tibia length ratios about 2.0-2.3. Chaetotactic formulae of leg segments as given for species-group. Tarsi II-IV with ventroapical process (12 – 17) bluntly pointed, smooth apically ( Figs 13A, H ), and with setae (d-1) (23 – 30) slightly shorter than pretarsus to base of claws (28 – 37). Tarsi II-IV with paradactyli asymmetrical, anterior element increasingly extending beyond tip of claw from II to IV, its length 30 – 35, twice as long as claw (15) on leg IV ( Fig. 14A ). Tarsi II and III with setae (l-1) and (v-1) symmetrical in form, pl-1 (32 – 35) and av-1 (36 – 47) slightly longer than al-1 (27 – 30) and pv-1 (26 – 37), respectively. Tarsus IV with distal seta av-1 (50 – 60) blunt, clearly larger, thicker than pv-1

(37 – 45); adjacent setae (l-1) symmetrically short (20 – 27), slender ( Fig. 14A ). Tarsi II-IV with dorsal seta md nearly reaching base of claws, and nearly as long as smooth attenuated setae (d-2) (67 – 80 on II, 85 – 100 on III, 95 – 110 on IV).

Adult male. Legs I clearly longer than dorsal shield, not thicker than those of female; relative leg lengths, excluding pretarsi, similar to those of female, I 550 – 660, II 445 – 524, III 455 – 552, IV 575 – 675. Legs with segment length ratios as in female. Tarsus I with long pretarsus (25 – 37 to base of claws), claws 10 – 12 long. Tarsi II-IV with dorsoapical setal processes (d-1), ventroapical process and pretarsal structures formed as in female, pretarsus lengths 27 – 35 excluding claws (10) ( Fig. 13B ). Legs III-IV with tibial setae (v) and leg IV genual seta av dimorphically thicker, spinelike, less attenuate; length and form of other setae much as in female; seta pl-3 of basitarsus II smooth, attenuate (36 – 38) ( Fig. 13B ), but pl-3 of basitarsi III, IV (21 – 22) similar to pl- 2 in thicker, slightly shorter form than other three basitarsal setae.

Type material — Except the final one, noted below, all specimens collected at the La Selva Biological Station, Heredia Province, Costa Rica (10°26´N, 84°01´W, elevation 50-150 m): HOLOTYPE: adult female, 8 July 1997, ex adult Cephaloleia bella Baly on Heliconia pogonantha leaves, coll. M. Paniagua. PARATYPES: 1 adult female, 1 adult male, with same data as holotype; 2 adult females, 1 adult male, 12 June 1997, ex coexistent adults of Cephaloleia belti Baly and C. ornatrix Donckier from Heliconia leaves, coll. ALAS; 3 adult females, 2 adult males, 15 April 1994, ex adult Chrysomelidae , no host plant data, M. Paniagua coll.; 1 adult female, 1 adult male, June 1997, ex adult Cephaloleia bella Baly , no host plant data, coll. D. Johnson; 1 adult female (gravid with larva), 1 adult male, June 1997, ex adult Cephaloleia belti Baly , no host plant data, coll. D. Johnson; 2 adult males, February 1994, associated with adult Chelobasis sp. on leaves of Heliconia pogonantha , coll. E.E. Lindquist & ALAS; 1 adult female, 2 adult males, 18 February 1994, ex adult Chrysomelidae , no host plant data, coll. ALAS; 3 adult females, 2 June 1997, with adult hispine beetles on Heliconiaceae leaves, coll. E.E. Lindquist; 2 adult females, June 1997, ex adult Cephaloleia vicina on Heliconia pogonantha , coll. not indicated; 1 adult male, February 1994, associated with adult Cephaloleia vicina on leaf of Heliconia pogonantha , coll. E.E. Lindquist & ALAS. Costa Rica, Osa Peninsula, Corcovado National Park (8°27.39´N, 83°25.45´W,elevation 10-500 m): 1 adult male, May 1997, ex adult Chelobasis bicolor Gray , no host plant data, coll. D. Johnson.

Host identifications — Some of the identities of the associated beetles given above are in accord with current molecular studies, i.e., those as noted below for Lasioseius serripes . However, the following identities are discordant. Cephaloleia vicina does not occur at La Selva, and specimens identified as such from there are, in all cases checked by DNA barcodes, C. bella . Further, C. bella normally does not occur on Heliconia pogonantha ; thousands of field diet records indicate it feeds only on H. imbricata ( Garcia-Robledo et al., 2017) .

Etymology — The specific name is based on the chrysomelid subfamilial name Cassidinae , which includes the tribes Arescini and Imatidiini (or Cephaloleini) to which beetle associates of the genera Chelobasis and Cephaloleia belong, respectively. We have chosen this name for the species with the widest array of host associates and as the species-group name, anticipating that rolled-leaf beetles of other genera in these tribes will be found to live with these mites.

Remarks — The male from Corcovado measured ca 12-19% smaller in dimensions than seven males measured from La Selva; however, in other descriptive aspects it fully resembles those from La Selva. Two females are asymmetrical in having humeral seta r3 inserted off the dorsal shield on one side, yet the aligned r2 and r4-r6 are on the shield. Two females show asymmetry in size and arrangement of the vertical cluster of setae j1, j2, z1; one male lacks one j2.

Collection records of this mite species associated with beetles of three different species of Cephaloleia and one of Chelobasis leave uncertainty as to host preferences, particularly as beetles of these species are often coexistent ( Garcia-Robledo 2010, Staines 2011, Schmitt & Frank 2013, Moraza & Lindquist 2015). Adults of Lasioseius cassidini are clearly the largest of the described species of this group. However, the data available are inadequate to test whether a mite/beetle size correlation exists, such as was hypothesized for larger mites being associated with larger beetles, for species of Hispiniphis and Makarovaia , which are more intimate subelytral associates of these same beetles ( Moraza & Lindquist 2015, 2016). Although there are records of a few specimens of L. cassidini with relatively large beetles of Chelobasis , including one from the Osa Peninsula, they are based only on adult male mites, which may not present inherent preferences phoretically. Tentatively, subject to further studies, we conclude that, at La Selva, Lasioseius cassidini may be associated regularly with small beetles of the host specialist Cephaloleia bella and to some extent with the host generalist C. belti on Heliconia imbricata .

Figures

Figure 1 Lasioseius cassidini n. sp. adult female: A – Idiosoma, dorsal view; B – Detail of denoted dorsal setae; C – Idiosoma, ventral view; D – Gnathotectum; E – Subcapitulum; F – Spermathecal structures; G – Fixed cheliceral digit in ventral view; H – movable cheliceral digit in partially lateral view.

Figure 2 Lasioseius cassidini n. sp., adult male: A – Idiosoma, ventral view; B – Variant form of ventrianal shield; C – Gnathotectum; D – Subcapitulum and ventral setae of palptrochanter; E – Detail of denoted dorsal setae, showingR2 on variant platelet; F – Cheliceral digits and spermatodactyl, dorsal view; G – Cheliceral movable digit, spermatodactyl, and corniculi, dorsal view; H – Detail of fixed digit, ventral view.

Figure 11 Distal subcapitular region, adult males: A –L. cassidini; B – L. serripes; C. — L. fuscina

Figure 12 A-D – Leg II, dorsal view (right leg, excluding tarsus, coxa and trochanter), adult males: A—Lasioseius serripes n. sp.; B – L. serripes, detail of ventral setaeon genu and tibia III; C –Lasioseius cassidini n. sp.; D – Lasioseius fuscina n. sp. E, F – Lasioseius duobtusisetis, adult female, tarsus I right leg, dorsal view: E – General aspect without detail of dorsodistal sensorial area; F – Detail of dorsodistal sensorial area. G – Lasioseius serripes, protonymph, tarsus IV left leg; H — Lasioseius sp. undescribed. adult female, tarsus IV right leg, ventral view. (Solid black setae in figures A-G and solid black circles in figures G and H indicate dorsal setae).

Figure 13 Tarsus II, right leg. A, B, H.Lasioseius cassidini n. sp.: A – Adult female, dorsal view; B – Adult male, dorsal view; H — Detail of distal region, lateroventral view. C, D, G.Lasioseius serripes n. sp.: C – Adult female, dorsal view; D – Adult male, anterolateral view; G. Detail of distal region, ventral view. E, F.Lasioseius fuscina n. sp.: E – Adult male, dorsal view; F – Adult female, dorsal view. I —Lasioseius duobtusisetis n. sp., adult female, dorsal view. (Solid black color indicates dorsal setae on segment).

Figure 14 Tarsus IV, adult females, right leg, ventral view: A –Lasioseius cassidini n. sp.; B – Lasioseius serripes n. sp.; C – Lasioseius duobtusisetis n. sp.; D – Lasioseius fuscina n. sp. (solid black circles indicate dorsal setae insertions).