Fortuynia atlantica

Pfingstl, Tobias & Schuster, Reinhart, 2012, First record of the littoral genus Alismobates (Acari: Oribatida) from the Atlantic ocean, with a redefinition of the family Fortuyniidae based on adult and juvenile morphology, Zootaxa 3301, pp. 1-33 : 11-18

Juveniles of Fortuynia atlantica – common features

Apheredermous. Colour black, cuticle shiny appears polished. Majority of integument thick sclerotized, except for lateral folds surrounding centrodorsal plate ( Figure 13 ). Due to their dark coloration nymphs showing generally a strong similarity to adult specimens under dissecting microscope. Gastronotic region strongly dorsoventrally flattened, whole body streamlined shaped. Prodorsum triangular. Rostrum rounded demarcated from remainder of prodorsum by an inconspicuous transverse ridge. Rostral setae (ro) long, thin and smooth. Lamellar setae (le) simple, smooth, half the length of (ro). Exobothridial setae (ex) minute and interlamellar setae (in) only vestigial. Sensilla short, capitate and overall smooth. Bothridia cup-like, narrow orifice with lateral incision. Medially on posterior border of prodorsum two paired groups of distinct pores leading into tracheal tubes ( Figure 7 B); in dorsal view covered by anterior folds of gastronotic region. Gnathosoma no obvious differences to adult stage. Pedipalp pentamerous 0-2-1-3-9 (solenidion included). Rutella broad, with membranous margin. Setae a and m thin, simple of normal length. Seta h long, smooth and spiniform. Lateral posterior borders of mentum tip-like elongated. Hysterosoma slightly convex. Hysterosomal cupules present but difficult to trace in any stage. Large centrodorsal plate finely punctate and stronger sclerotized, bearing all notogastral setae, except for c 1-3 in all stages and seta h 2 in the larval stage. Lateral borders of plate straight, anterior border slightly convex, posterior border strongly convex. In nymphal stages posterior part of centrodorsal plate showing a median lesser sclerotized smooth area resembling an inverted Y, whereas longitudinal line long reaching anterior third of plate. Large folds surrounding centrodorsal plate. Within lateral folds a series of longitudinally arranged fine but distinct pores, each turning into fine tracheal internal tubes ( Figure 14 ). Orifice of opisthonotal gland (gla) in posterior half of lateral folds. Small porose areas associated with bases of notogastral setae. A series of large darker spots arranged in two longitudinal rows, in anterior part of centrodorsal plate spots aligned transversally connecting longitudinal rows; these darker areas generally difficult to trace. Ventrosejugal suture developed as distinct furrow, resembling medially a broad V. Nymphs with no distinct genital valves, genital orifice a longitudinal slit, inner margins with conspicuous granules. Anterior to genital opening a slightly rostrad curved canal-like fold. Posterior to anal region caudad arched furrows, along these folds singular fine pores ( Figure 15 ). Legs monodactylous. Integument showing same pattern as in adults, trochanters dark, heavily sclerotized, proximal third of femora light, remainder dark, genua dark, tibiae light, proximal part of tarsi dark and distal parts light. Dorsal setae of tibiae and genua absent when respective solenidion present. Solenidia on tibia I inserting on small apophysis. Large porose areas on ventral paraxial side of femora I and II and on dorsal paraxial side on femora III and IV. Circular or elliptic porose areas on paraxial dorsal side of trochanters III and IV. Tarsal lyrifissure already observable in all juvenile stages.

Larva. Length (N=3): 226–235 μm (mean 231 μm)

Gastronotic region ( Figure 16 A). Eleven pairs of strong, smooth and spiniform notogastral setae; c1-3, da, dm, dp, la, lm, lp, h1-2; h3 absent. All setae long, except for seta dm showing normal length, setae c1, la, lm and dp a third longer than remaining setae. Conspicuous transverse ridge on centrodorsal plate passing posterior line of setae dm and lm.

Ventral region of idiosoma ( Figure 16 B). Epimeral setation 3-1-2, seta 1c shaped valve-like protecting Claparède organ. Cuticle surrounding Claparède organ anteromedially strongly sclerotized, developed as protruding protective ridge. A transverse fold anterior of anal orifice.

Legs. Setation and solenidia see table 2.

Protonymph. Length (N=17): 258–306 μm (mean 287 μm)

Gastronotic region ( Figure 16 C, 17). Fifteen pairs of notogastral setae; c1-3, da, dm, dp, la, lm, lp, h1-3 and p1-3. Seta c1 and h1 longest, dm, dp and h3 shortest. Transverse ridge on centrodorsal plate passing posterior line of setae dm and lm, absent from this stage.

Ventral region of idiosoma ( Figure 16 D). Epimeral setation 3-1-2-1. Seta 1c ordinary seta, close to trochanter I, seta 4a near trochanter IV. One pair of genital setae, located in the middle of genital area. Aggenital setae absent. Setae p3 and p2 flanking anal opening.

Legs ( Figure 18 ). Chaetome and solenidia see table 2.

Instars Trochanter Femur Genu Tibia Tarsus Chaetome Solenidia

Leg I larva - d, bv´´(l), σ (l), v´, ϕ1 (pl), (pv), s, (a), (u), (p), (tc), (ft),?, ω1 0-2-2-3- 16 1-1-1 protonymph - - - - ω2 0-2-2-3- 16 1-1-2 deutonymph - l ´- j2 - 0-3-2-3- 16 1-2-2 tritonymph - l ´´ - - (it) 0-4-2-3- 18 1-2- 2 adult* v ´´ - - - - 1-4-2-3- 18 1-2-2

Leg II larva - d, bv´´(l), σ l´, v´, ϕ (pv), s, (a), (u), (p), (tc), (ft), ω 0-2-2-2- 13 1-1-1 protonymph - - - - - 0-2-2-2- 13 1-1-1 deutonymph - l ´´ - - - 0-3-2-2- 13 1-1-1 tritonymph - l ´- - (it) 0-4-2-2- 15 1-1- 1 adult * v ´´ - - l ´´ - 1-4-2-3- 15 1-1-1

Leg III larva - d, bv´l´, σ v´,ϕ (pv), s, (a), (u), (p), (tc), (ft) 0-2- 1-1-13 1 -1-0 protonymph - - - - - 0-2- 1-1-13 1 -1-0 deutonymph v ´- - - - 1-2- 1-1-13 1 -1-0 tritonymph - l ´- l ´(it) 1-3-1-2-15 1-1-0 adult* l ´- - l ´´ - 2-3-1-3-15 1-1-0

Leg IV protonymph - - - - (pv), (u), (p), ft´ 0-0-0-0-7 0-0-0 deutonymph - d, bv´d, l´v´, ϕ s, (a), (tc) 0- 2 -2-1-12 0-1-0 tritonymph v ´- - l ´- 1-2-2-2-12 0-1-0 adult* - - - l ´´ ft´´1-2-2-3-13 0-1-0 Deutonymph. Length (N=22): 306–369 μm (mean 341 μm)

Gastronotic region ( Figure 19 A). Fifteen pairs of notogastral setae, same positions and shapes as in protonymph.

Ventral region of idiosoma ( Figure 19 B). Epimeral setation 3-1-2-2, seta 4b median on epimeral plate IV. Two pairs of genital setae in a longitudinal row. One pair of simple and short aggenital setae ag laterad of posterior genital setae. Three pairs of adanal setae ad1-3 flanking anal valves. Two pairs of vestiges on anal plates.

Legs ( Figure 20 ). Chaetome and solenidia see table 2.

Tritonymph. Length (N=15): 395–431 μm (mean 415 μm)

Gastronotic region ( Figure 19 C). Fifteen pairs of notogastral setae, no difference to deutonymph.

Ventral region of idiosoma ( Figure 19 D). Epimeral setation 3-1-3-2, seta 3c next to trochanter III. Four pairs of short genital setae arranged in two longitudinal semicircles. One pair of aggenital setae ag. Three pairs of adanal setae ad1-3 flanking anal opening, whereas ad1 twice as long as others. Two pairs of anal setae an1-2.

Legs. Chaetome and solenidia see table 2.

Figures

FIGURE 7. Prodorsal pores in fortuyniid immatures. A) Alismobates inexpectatus. B) Fortuynia atlantica.

FIGURE 13. Fortuynia atlantica LM-micrographs. Scale bar: 50 µm. A) protonymph dorsal view, layered from 13 images. B) deutonymph ventral view, layered from 10 images. C) tritonymph lateral view, layered from 10 images.

FIGURE 14. F. atlantica micrographs of nymphs, lateral view. A) lateral folds, arrow points to series of pores, lbc = lateral border of centrodorsal plate. B) enlarged view of pores associated with fine tracheal tubes (best observable in centre of photograph).

FIGURE 15. F. atlantica tritonymph, micrograph of left anogenital region. Arrowheads pointing to pores aligned in ventral furrows.

FIGURE 16. F. atlantica. A) larva dorsal view. B) larva ventral view C) protonymph dorsal view. D) protonymph ventral view.

FIGURE 18. F. atlantica protonymph left legs antiaxial view. A) leg I. B) leg II. C) leg III. D) leg IV.

FIGURE 19. F. atlantica. A) deutonymph dorsal view. B) deutonymph ventral view. C) tritonymph dorsal view. D) tritonymph ventral view.

FIGURE 20. F. atlantica deutonymph right legs antiaxial view. A) leg I. B) leg II. C) leg III. D) leg IV.