Fortuynia elamellata micromorpha, Marshall & Pugh, 2002

Marshall, David J. & Pugh, Philip J. A., 2002, Fortuynia (Acari: Oribatida: Ameronothroidea) from the marine littoral of southern Africa, Journal of Natural History 36 (2), pp. 173-183 : 179-182

Fortuynia elamellata micromorpha subsp. nov.

(®gure 5)

Material. More than 40 specimens collected by D. J. Marshall and K. Ugrasen during 1998 and 1999 from barnacles, oyster shells and shale deposits, on the mid to upper rocky shore at Park Rynie, Kwa Zulu-Natal, southern Africa (30ss21¾ S, 30ss43¾ E). Seven females examined in detail. Holotype and two paratypes will be deposited in the Natural History Museum , London , UK, and three paratypes in the 14 National Museum, Bloemfontein, South Africa.

Etymology. Subspeci®c name refers to the small size relative to nominate subspecies.

at Idiosoma. Female 380±404 Mm long and 206±215 Mm wide. Brown to dark brown. Oval.

Prodorsum. Surface ®nely punctate. Lamellar ridges absent. Rostral setae of

smooth (38±45 Mm), lamellar setae smooth (32±38 Mm), interlamellar and exobothridial setae vestigial. Bothridia not covered by notogastral margin. Sensillus smooth, thin-walled, sharply medially incurving, clavate and large. Dorsosejugal, notogastral and lateral channels of van der Hammen’ s organ present, but prodorsal channels absent.

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Notogaster. Surface smooth and punctate. Colour brown with lighter areas anteriorly (a probable lenticulus). Fourteen pairs of long, thick, ®nely pointed and smooth notogastral setae. Separation of setae c1 sub-equal to that of c1 and c2. Setae c3 absent, vestiges not observed. All d setae of a similar length; da posterior of and similar in length to la, and shorter than separation of da setae. Setae h2 notably longer than other dorsal setae. Setal lengths (range for ®ve individuals) as follows: c1 54±65, c2 33±45, la 49±58, lm 53±63, lp 54±68, da 55±60, dm 53, dp 55± 63, h3 53±65, h2 80±105, h1 35±45, ps3 30±45, ps2 30±53, ps1 63±77. Lyri®ssures ia lateral of c2 and im between setae lm and lp. Lyri®ssures ih, ip and ips not seen. Glandular opening (gla) lateral to im.

Venter. Entire surface lightly punctate. Pedotectum I conspicuous. Foveate plastron extends along the outer margin of coxisternum, between acetabulum I and IV and posteriorly on latero-ventral plate, below notogaster, but not medially along epimeral border III. Sternal apodeme disintegrates anteriorly in epimeres I. Epimeral setation: 3-1-3-2. Epimeral setae 17±38 Mm long. Genital plates darker than, but anal plates the same shade as the ventral surface and epimeral plates. Genital plates trapezoid (72 Mm long and 41±44 Mm wide), each typically bearing ®ve setae, around 20 Mm long. Anal plates large (80±85 Mm long and 30±34 Mm wide), each typically bearing two setae. Preanal organ large and dark. Aggenital setae anterior to level 14

at of by of setae g2. Adanal setae ad3 anterior of lyri®ssure iad, and ad2 lateral to this. Anal and adanal setae long (28±34 Mm). Subcapitular seta h long.

Legs. Femora and genua of all legs dark brown with ®nely pitted cuticle. Slight darkening of proximal and distal ends of tarsus and tibia, respectively. Lengths of femur, tibia, tarsus and claw (rounded mean in Mm; n 53) as follows: leg I 107, 52,

44, 33; leg II 91, 44, 41, 32; leg III 66, 65, 45, 33; leg IV 80, 67, 46, 34. Diagnostic setation: genu I: seta d long and smooth, abaxial lateral seta l ² and adaxial l ¾, both approximately half this length and barbed; genu II: smooth dorsals and barbed laterals (l ¾ and l ²), all subequal in length (®gure 2 C). Tibia III distinctively long, almost as long as femur III. Tarsi each with a single, slender open claw, only slightly shorter than tarsus.

Discussion

The three Fortuynia taxa presented in this study diOEer markedly in size and shape; F. rotunda is considerably larger and rounder than the other species. The structure of van der Hammen’s organ, particularly the presence of an external prodorsal channel (ce), groups F. rotunda sp. nov. with F. marina , F. yunkeri and F. maculata (van der Hammen, 1960, 1963; Luxton, 1967). In contrast, F. inhambanensis sp. nov. and F. elamellata micromorpha subsp. nov. lack this channel and are grouped with F. elamellata elamellata , F. e. shibai and F. sinensis (Luxton, 1967, 1992; Aoki, 1974). Fortuynia rotunda sp. nov. is also similar to F. marina with regard to numerous dorsal characters. They uniquely share both external and internal prodorsal channels (ce and ci; though ci does not reach the interlamellar vestige in 14 F. rotunda), and extremely short posterior notogastral setae. However, F. rotunda sp. nov. diOEers from F. marina in a number of ventral characters. The ventral surface of F. rotunda sp. nov. resembles that of F. maculata ; both have long ventral setae, an anteriorly disintegrating sternal apodeme, and epimeral borders I and II abutting at

on the mid-sternum.

Within the group lacking the external prodorsal channel (ce), F. sinensis diOEers of from F. elamellata elamellata and F. elamellata shibai by the absence of`tuberculation posteriorly of apodemata IV’ (Luxton, 1992, sic) and the presence of an internal prodorsal channel (ci). Features distinguishing F. e. shibai from F. e. elamellata include: (1) relatively short da setae (shorter than separation of da setae); (2) setae la anterior of da; (3) aggenital setae anterior to level of genital setae g2; and by (4) pedotectum I well-developed (see Aoki, 1974). Fortuynia ellamelata micromorpha subsp. nov. more closely resembles F. e. shibia than F. e. elamellata , but diOEers from F. e. shibia in being small and oval (idiosomal length is 380 Mm, whereas that of both F. e. elamellata and presumably F. e. shibia is around 480 Mm), in having long anal setae (some nearly twice as long as those indicated for F. e. shibia), and in the plastron not bordering epimere III. Fortuynia elamellata has previously only been reported from New Zealand and Japan (Luxton, 1967; Aoki, 1974), thus this new southern African record notably extends the Indo-Paci®c distribution range of the species.

Fortuynia inhambanensi s sp. nov. is unique among the Fortuynia species in lacking aggenital setae and in having lamellar ridges in some individuals. Previously, the external prodorsal channel of van der Hammen’s organ has been mistaken for a lamellar ridge (van der Hammen, 1960, 1963). Eight characters distinguish F. inhambanensis sp. nov. from its southern African rocky shore counterpart, F. e. micromorpha subsp. nov.: (1) medial dorsosejugal line straight and not curved; (2) distance between setae c1 more than twice that between c1 and c2; (3) setae da anterior to or level with la; (4) relatively short epimeral setae; (5) genital plates rectangular, and both genital and anal plates the same shade as the ventral surface (genital plate darker than ventral surface in F. e. micromorpha); (6) both ad2 and ad3 anterior of iad; (7) legs shorter, particularly podomeres tibia III and IV, and femora IV; and 14

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