Reginacharlottia Walter, 2013, gen. nov.
Creators: name: Walter, David Evans
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Mesostigmata
Uropodellidae
Reginacharlottia

description: Reginacharlottia gen. nov.
Type species: Reginacharlottia lordhowensis sp. nov.
Diagnosis. Adults, nymphs, larvae: Chelicera with edentate, regressed fixed digit covered by expanded, membranous cheliceral seta and elongate plumose interdigital excrescence (Figs 14, 21, 24–25) issuing from near base of movable digit; pilus dentilis minute; palpal apotele with two subequal tines and strong dorsal spur; hypostomal seta h1 flattened, membranous (Figs 5, 24); tritosternal base with short lateral extensions (Fig. 7), laciniae completely divided; postanal seta absent; legs I antenniform, tarsus I subcylindrical, without apotele (Figs 12, 28, 30). Adult male and female: anal opening (Figs 6, 11) on small shield overarched by pair of hypertrophied setae, ringed by accretion-like array of small setae and scale-like platelets; at least seven pairs of setae in sternogenital region (Figs 16, 17, 35); av4, pv4 on intercalary sclerite on tarsus IV; coxa II with three setae including small, bifurcate dorsal seta; genu I with eight or nine setae; soft cuticle bearing numerous setae with ventral rib and overlapping dorsal scales, each seta inserted on ribbed base (Fig. 17); corniculi setiform (Fig. 5 c); tritosternal laciniae free, base slightly expanded laterally; metapodal plate fused to peritrematal shield. Adult female: podonotal-mesonotal shield truncate (Fig. 34) to eroded (Fig. 1) posteriorly, projecting vertex-like over the gnathosoma (Fig. 2), joined to broad peritrematal-metapodal shield (Fig. 15); pygidial shield reduced to remnant; free lateral, mesonotal, and posteromarginal shields or platelets absent; genital shield (Figs 3, 35) reduced, straplike plate, nude or with 1–2 setae. Adult male: podonotal-mesonotal shield extended posteriorly to cover most of idiosoma, creased at level coxae IV (Fig. 19); venter covered by large, angular shield bearing numerous setae (Fig. 20); genital opening on intercoxal shield bearing seven pairs of setae and covered by two nude valves (Fig. 18).
Remarks. Reginacharlottia contains a perplexing mix of apparently primitive and markedly aberrant character states. The plumose, feather boa-like process on the chelicera is otherwise unknown in the Sejoidea, but similar to excrescences found on the fixed digits in the Trigynaspida, the only other suborder of Mesostigmata to retain the intercalary sclerite on tarsus IV bearing setae av4, pv4 (also found in the other orders of Parasitiformes). Female trigynaspids, however, are usually well sclerotised, and even the exceptions with reduced sclerotisation (e.g. Davacaridae) have several shields covering the genital opening. Also, the excrescences in the Trigynaspida can usually be traced to openings in the movable cheliceral digit. No such opening has been observed in Reginacharlottia, and the excrescence appears to issue from the arthrodial membrane at the articulation of the movable and fixed digits, as do the interdigital membranes in the Heterozerconidae. Until the homology of these structures can be tested, I use the term interdigital cheliceral excrescence for the structure in the new genus.
With the exception of the cheliceral excrescence, however, the new genus is in substantial agreement with the diagnosis for Sejida (= Sejoidea) in Lindquist et al. (2009) with these exceptions, Sejida (vs Reginacharlottia): venter of female with large ventri-anal shield (reduced to small ventri-anal shield); metapodal plates usually free and well developed (fused to peritrematal shield); genital shield large, usually bearing two or more pairs of setae (genital shield a strap-like remnant usually nude, but rarely captures 1–2 setae); palpal apotele 2-tined (2 tines + large dorsal spur). The palpal apotele is a supposed remnant of the palpal claw complex. The basic construction of the tarsal claws in arachnids is composed of three parts, a pair of lateral claws and a central claw or pad. Usually the palptarsal apotele has a maximum of three tines in the Mesostigmata (four in some Veigaiidae), presumably representing the plesiotypic tridactyl condition. In the Sejida, and convergently in other groups of Mesostigmata, this may be reduced to two tines and sometimes a basal spur is present that appears to be the remnant of the missing tine. However, although not previously reported, Sejus americanus (Banks, 1902), has a similar spur on its palpal apotele (Fig. 43), so this character state is present in the traditional Sejida (= Sejoidea).
Other character states also suggest that Reginacharlottia belongs in the Sejoidea. For example, the strong tuberculate ornamentation of the shields (e.g. Figs 22, 23) is characteristic of members of the Sejoidea, as is the podonotal-peritrematal shield in the female. Moreover, although the genital shield in the female is strongly reduced (Fig. 3), it bears a modified region on the anterior border found in members of the Sejoidea where the spermatophore is attached (see Fig. 50). Additionally, the anterior hypostomal seta (h1) is typically modified into a pair of closely inserted and largely membranous structures in the Sejoidea (e.g. Figs 41, 51).
Etymology. The new genus is feminine and named for Lord Richard Howe’s flagship the Queen Charlotte during the Battle of Ushant, an action claimed as a victory by both contestants, as an allusion to the confusing nature of characters displayed by the new genus and to the type species locality: Lord Howe Island, New South Wales, Australia.
Reginacharlottia lordhowensis sp. n. Figures 1–30, 48–49.
Specimens examined. Holotype female, Lord Howe Island, New South Walter, Australia; ex leaf litter in closed rainforest Cleistocalyx / Chionanthus habitat (LHISO26L) on Boat Harbour walking trail 400m before harbour (31°33' 32”S, 159°05' 34”E), 21 November 2000. In Australian Museum, Sydney. Paratypes: 24 females (4 with larvae), 12 males, 2 deutonymphs, 1 protonymph, same data except from various litter types (sclerophyll, closed rainforest forest, palm) Boat Harbour, Erskine Valley, Dawson Point Ridge, Goat Home, Phillip Point, and Mount Gower, 21 November 2000 to 8 June 2003; 2 females Intermediate Hill, Goat house walking track (31°33' 15”S, 159°04' 57”E) ex Howea fosteriana palm litter (LHI/JT/09L), 23 February 2001, J. Tarnawski & M. Shea; 1 female ex moss, lichens, liverworts (LHI/JT/10L) near Goat House Cave, 23 February 2001; 2 males, 1 deutonymph Little Island behind Far Flats (31°34' 8”S, 159°04' 52”E) ex Howea fosteriana litter (1HO21A), 10 August 2001; 1 deutonymph 100 m east Soldier Creek (31°34' 55”S, 159°05' 09”E) ex Cleistocalyx fullageri litter (RATSCF7-3L), 8 June 2003; 1 protonymph, beside walking track, 3rd Tee (31°33' 11”S, 159°05' 01”E), 28 May 2003, RATGCFC 2-1, ex litter lowland mixed forest, I. Hutton, K. Lees. In Australian Museum, Sydney; Australian National Insect Collection, Canberra; Royal Alberta Museum, Alberta, Canada; Acarology Laboratory, Ohio State University, Columbus, OH, USA.
Diagnosis. With the characteristics of the genus, podonotal-metanotal shield tubercles flattened, irregular, with marginal lamellae (Fig. 22), posterior margin of podonotal-metanotal shield eroded medially (Fig. 1); peritrematalmetapodal shield with tuberculate ornamentation similar to podonotal-metanotal shield (Figs 2, 15, 20); movable cheliceral digit ending in three minute teeth; soft cuticle with plicate-reticulate ornamentation (Figs 9–11). Genual setation I–IV, 9-12-12-12, respectively; tibia IV with 11 setae.
Female (n = 24). Body (Figs 1–2, 30) sack-like 875–1200 µm long, 770–1100 wide (body expands as eggs develop).
Cuticle. Most sclerotised shields (podonotal-metanotal, peritrematal, ventral, pygidial) ornamented with flattened tubercles with irregular marginal lamellae interspersed with minute (1–3) denticles and surrounding raised muscle insertions (Figs 1–2, 22–23); ventri-anal shield (Figs 6, 11) formed from scale-like platelets; legs with scale-like reticula with smooth or toothed margins (Fig. 13). Soft cuticle plicate, ridges smooth to denticulate, larger denticles forming reticulate pattern (Figs 3, 11); numerous subdermal pores, hypertrichous. Setae (mostly 24–37 long, up to 20 wide) with ventral rachis and dorsal array of imbricate scale-like ornamentation resembling conifer-cones (Figs 11, 17), each inserted on small, raised, ridged platelet (see Figs 17, 23).
Gnathosoma. Chelicerae (Fig. 14) short (73 long including regressed fixed digit ~20–25), pilus dentilis minute setiform, cheliceral seta (~23 long) membranous, expanded and covering fixed digit; Movable digit 32–35 long, smooth, tapering to 3 small distal teeth. Feathery interdigital excrescence (37–45 long) apparently issuing from soft cuticle at juncture of digits and extending well beyond chelicera. Anterior hypostomatal seta h1 (18–20 long) flattened, membranous (Figs 4–5); outer hypostomatal seta h2 (35–38) with 8–11 short branches distally; inner hypostomatal seta h3 (43–50) flattened, whip-like; corniculus (13–15) setiform, curved, trifurcate distally; palpcoxal seta (17–25) simple. Deutosternal groove narrow, obsolescent, with six pairs of small teeth, slightly widened ventrally; three pairs semi-lunar arrays of denticles posteriad palpcoxal setae. Ve n tr al se ta v1 (Figs 4–5) of palptrochanter (23–27) rake-like with 5–6 ventral tines. Palptarsal apophysis 2-tined and with short, dorsal spur (Fig. 27 arrow). Setation of palpal trochanter-femur-genu-tibia-tarsus: 2-5-6-14 -15 (10 in terminal cluster).
Dorsum. Prodorsal-metanotal and peritrematal shields (Figs 1–2, 15) ornamented with large (mostly 10–15 long) flattened tubercles, angular to rounded in shape, and large, raised, finely punctate muscle insertions; vertex subrectangular with two pairs of setae on anterior margin, projecting over gnathosoma; prodorsal-metanotal shield bilobed posteriorly (lobes 500–550 long) with deep (100–150) medial incision; peritrematal shield very broad (to~ 100), extending posteriorly around coxa IV to capture metapodal plate; peritreme sinuate, extending along medial margin of shield from posterior corner of vertex to stigma at level of coxa IV, with post-stigmatal gutter extended posterior to coxa IV. Pygidial shield (Figs 9–10) minute (18–37 long x 21–45 wide), without setae, with central tubercle divided into 2–3 and 4–12 satellite tubercles.
Venter. Sternal region (Figs 7, 16) with reticulate pattern, lightly sclerotised, reticulate and bearing st1 – 3; st1 thick, covered in barbs on ventral surface and distally; st2 (41) barbed, tapering; st3 simple to lightly barbed; st4 – 7 simple, in soft cuticle; rarely spurious seta on small platelet carrying pore (stp3?). Genital shield (Fig. 3) (100 long x 43 wide) without setae or rarely with st7 captured asymmetrically, ornamented with small denticles and irregular tubercles, smooth area on anterior margin of shield for attachment of spermatophore, two pairs lyrifissures in soft cuticle. Anal opening (Figs 2, 6, 11) in irregular conical shield (87 long x 100 wide) composed of scale-like platelets and outer array of 20 or more small platelets each bearing a smooth, tapering seta inserted on raised, ridged projection; inner region of scale-like platelets with anterior pair of flattened, tapering setae (90–92 long) projecting over opening, covered by pair of small (~25 long), nude valves.
Legs. (Figs 13, 28–30) Legs II–IV laterally flattened, strongly ornamented (Fig. 13); leg I (570) about half length of body, slender, antenniform, without apotele or acrotarsus (Fig. 28). Setation of tarsi: basitarsus II–IV each with four setae; telotarsi II–III with 14 setae, telotarsus IV with 14 plus av4, pv4 on intercalary sclerite. Setation of legs I–IV, respectively, coxae: 2-3-2-1 (coxa II with small [9-10] dorsal seta divided distally); trochanters: 6-5-5-5; femora 11-9-7-8; genua 9-12-12-12; tibiae: 8 (larval)- 10-10-11; femora I–IV: 2-5/2-2; 2-4/2-1; 1-4/1-1; 2-(2+3)-1; genua I–IV: 2-2/1, 3/0-1; 2-3/1, 3/1-2; 2-3/1, 3/1-2; 2-3/1, 3/1-2; tibiae I-IV: 2-2/1, 2/0-1; 2-2/1, 2/1-2; 2-2/1, 2/1-2; 2-2/2, 2/1-2.
Male (n = 12). Similar to female except dorsum covered by a single, large (640 long, 460 wide) shield, transverse fold present just anterior to the metapodal muscle insertions at level coxae IV (Fig. 19). Sternitogenital shield (Fig. 18) (152 long, 135 wide at endopodals II) reticulate to posterior margin of genital opening, then tuberculate; bearing seven pairs of setae, two pairs of lyrifissures (stp1, stp3; stp2 not present or obscure), genital opening covered by a pair of transverse, nude valves between coxae III; median gland opening just posterior to level of st4 – 5 pair; st1 (33) thick and coarsely barbed, st2 – 3 (25) barbed, tapering, st4 – 7 (~15) with inflated bases, whip-like tips; st4 – 5 insertions approximate, st6 – 7 insertions variable. Large (228 long, 355 wide) ventral shield present encompassing anal shield and bearing numerous setae, ornamented with tooth-like tubercles and denticles (Fig. 23).
Deutonymph (n = 2). Structure of gnathosoma, cuticular ornamentation, form of idiosomal setae and ornamentation of plates similar to adults. Podonotal shield truncate and separate from broad mesonotal plate bearing either 6 or 25 setae. Sternal region with five pairs of setae, but without distinct shield. Anal shield similar to adults, but with three pairs of small setae and overarching pair of hypertrophied setae.
Protonymph (n = 1). Similar to other stages but palpal trochanter with one seta; podonotal shield truncate posteriorly; a pair of small, nude mesonotal scutellae present; sternal region with weakly differentiated shield bearing st1 – 3; anal shield similar to deutonymph, but with two pairs of small setae and overarching pair of hypertrophied setae; tarsus IV with av4, pv4 on intercalary sclerite.
Egg and larva. (Figs 48, 49) Female with up to 12 large (>300 long) eggs with fully developed larvae. Larval idiosoma (~330 long) encased in lightly sclerotised, reticulate cuticle except smooth in intercoxal region. Dorsal seta j1 (86 long) densely barbed in distal 3/4th, widely separated (35 between insertions) (Fig. 48); other setae roughened with incipient barbs; j3 (132 long, 28 between insertions), j4 – 5, z2, z4, s4, s6, J2 – 5, Z3 – 5, S3 – 4 similarly ornamented (70–105 long), S5 (30) simple; j6 apparently absent; median horn-like pygidial tubercle (15– 20 high) present between J4 – J5 (Fig. 48 arrow). Sternal setae st1 – 3 (25–32 long) acicular, weakly barbed; JV1 similar (32 long); JV (5?) (46) barbed. Anal opening (Fig. 49) simple, para-anal setae (70 long) weakly barbed, inserted posteriad opening, postanal seta absent. Chelicerae (~60 long), interdigital membrane just passing (~4) tip movable digit (15 long) possibly edentate; setae h1 (~10 long) tapering, acuminate, slightly inflated (candle-flame shaped); h2 (~23 long) curved medially, barbed on outer distal side; corniculus minute (7–9), with three distal cusps. Deutosternal gutter obsolescent, with three rows of two denticles each. Tritosternum with simple columnar base, two thick laciniae (~35 long). Dorsal setae on palpgenu-tibia thick, blunt, curved (resemble solenidia); palptarsal apotele with strong basal spur.
Etymology. The species name is genitive and refers to the island of origin.
Remarks. Adult males and females of the new species were relatively frequent in soil-litter extractions (and one pit-fall trap sample), but never abundant compared with other Mesostigmata. The association of the following species with a large arthropod and the highly modified chelicerae and reduced legs I of both species in the new genus suggest that these mites may be associated with some larger animal. For example, the reduced legs I are reminiscent of some trigynaspid mites that are able to jump and are associated with beetles: Saltiseius hunteri Walter (Saltiseiidae) and Micromegislus bakeri Trägårdh (Walter 2000).
Other Sejoidea are known to disperse on insects associated with woody habitats. For example, deutonymphs of Uropodella lacinata Berlese have been reported to be phoretic on the tenebrionid beetle Neatus tenebrioides (Herbst) (Kethley 1983) and deutonymphs of Sejidae on cerambycid beetles (Halliday 2012). The deutonymphs attach to their beetle carriers via an anal stalk produced by a complex anal opening (Kethley 1983). Only two deutonymphs of the new species have been discovered and neither possessed a modified anal opening. However, the free mesonotal plate in one deutonymph was much larger than in the other specimen, and bore about four times as many setae. Given the difference in dorsal sclerotisation in the adults, these deutonymphs may represent the male and female, respectively.
Species of Asternolaelaps are often associated with mammal nests (Lindquist et al. 2009). Other than seabirds, however, Lord Howe Island has only a few rare endemic vertebrates (two lizards and a bat) and none that make nests in the closed forest litter habitats in which the mites were most frequently encountered (Hutton 1986).
The presence of fully developed eggs within four of the females examined and the egg burster-like pygidial tubercle on the larva suggest that hatching may occur at or very soon after oviposition. Micromegislus bakeri Trägårdh (Parantenulidae) is reported to give birth to active larvae on its host ground beetles (Nickel & Elzinga 1970). Egg bursters have been reported in the Prostigmata (Marchiando 1981), but not to my knowledge in the Mesostigmata.
Reginacharlottia braziliensis sp. n. Figures 31–35
Specimens examined. Holotype female, ex Trichodamon froes i Mello-Leitão, 1940 (Arachnida: Amblypygi: Phyrnidae), Caverna Agua Fina, Carinhanha, Bahia State, Brazil, 29 May 2012, M.E. Bichuett & J.E. Gallão. Type deposited in Department of Zoology, UNESP, Sao Paulo State University, Brazil.
Diagnosis. With the characteristics of the genus; podonotal-metanotal shield (635 long) densely setose and tuberculate: cuticular tubercles polygonal to substellate (Fig. 34), more or less contiguous; ca. 30 pairs of sigillar tubercles in podonotal region, metanotal region with two clusters of six sigillar tubercles; metapodal plates fused and joined to podonotal region at transverse fold; peritrematal-metapodal shield with fishscale-like reticulate ornamentation (Fig. 32), large gland opening about mid-shield; movable cheliceral digit (Fig. 33) ending in five minute teeth; soft cuticle with smoothly net-like ornamentation of narrowly elongate hexagons (Fig. 32), irregular polygons, and substellate cells. Tectum with smooth, rounded anterior margin. Genital shield (~105 long) with polygonal reticulation, surrounded by striate cuticle and seven pairs of setae (Fig. 35). Dorsal setae 22–30 long with ventral vane and dorsal conifer cone-like ornamentation, ventral setae similar, but strongly tapered, acuminate, barbs short. Leg setation: coxa I–IV: 3-3-2-1; trochanters I-IV: 6-5-5-5; femur I-IV: 11 (v = short spine) - 10 (2 basifemur) - 7-8 (1 on basifemur); genu I-IV: 8-11 (2-3/1, 3/0-2) - 10 (2-2/1, 2/1-2) - 11 (1-2/1, 3/1-2); tibia I-IV: 8-10 (2-2/1, 2/1-2) - 10 (2-2/1, 2/1-2) - 10 (2-2/1, 2/1-2); tarsus IV with intercalary sclerite bearing av4, pv4.
Remarks. Although only a single female specimen has been collected and the slide preparation is in poor condition (the body has burst, the sternal region cannot be observed, the subcapitulum is only partially visible, the pygidium is apparently absent), it seems appropriate to provide a diagnosis and name for the species to encourage its further study. The Brazilian specimen shares the diagnostic characteristics of Reginacharlottia, including the unique cheliceral modifications, setiform corniculus, palpal apotele with dorsal spur, rake-like ventral seta on the palptrochanter, uniquely formed ventri-anal shield, and conifer cone-like dorsal setae. However, it differs from the type species in the details of the ornamentation of the shields, the metanotal region (a single continuous metanotal plate bearing both pairs of muscle insertions is fused to the podonotal shield, see Fig. 34), the ornamentation of the soft cuticle (jigsaw-like patterns of deformed stellate cells or compressed hexagons, see Fig. 32), the more extensive distribution of tapered ventral setae, and some details of the leg setation, especially of the more reduced setation of the genua (8-11-10-11 vs 9-12-12-12).
description: Published as part of Walter, David Evans, 2013, A new genus and family of sejine mites (Acari, Parasitiformes, Mesostigmata, Sejoidea) based on new species from Lord Howe Island and Brazil, and a redescription of Sejus americanus (Banks, 1902), pp. 301-323 in Zootaxa 3691 (3) on pages 304-315, DOI: 10.11646/zootaxa.3691.3.1, http://zenodo.org/record/248009