Elpidium picinguabaense, Pereira & Rocha & Martens & Pinto, 2023

Pereira, Julia S., Rocha, Carlos E. F., Martens, Koen & Pinto, Ricardo L., 2023, Six new species of Elpidium Müller, 1880 (Podocopida: Limnocytheridae) from Eastern Brazil, Zootaxa 5258 (1), pp. 1-38 : 15-20

Elpidium picinguabaense n. sp.

Figs. 9–12

urn:lsid:zoobank.org:act:790F8E6A-3C45-4B1F-AC41-7E63807766DD

Diagnosis. Small-sized species (length of male = 655 µm; length of female = 686 µm) with greatly elongated carapace (width/length ratio = 0.7; height/length ratio = 0.5). Surface brownish with sparse setae, normal pore canals and subtle ornamentation. Left valve overlapping right one. Sexual dimorphism in lateral view subtle: posterior contour acuminated in both males and females. Ventral surface flat on central portion. In dorsal and ventral views, carapace symmetric and with stronger sexual dimorphism owing to external visible brood chamber in the female. In left lateral view, external flange small, dorsal margin slightly arched and ventral margin straight. Hinge bar long (slightly longer than 2/3 of dorsal margin length); anterior and posterior proto-teeth thin. Cop on hemipenis without differentiation of distal glans and ejaculatory duct, hook-like, with tapered apex. LR short with apex triangularshaped. DL elongated (basis width/distal lobe length ratio = 0.35), acuminate apex and with basal digital expansion relatively short and pointed.

Etymology. The specific epithet “ picinguabaense ” refers to the locality, meaning “ Elpidium from Picinguaba”, which is a village in the municipality of Ubatuba, north littoral of S„o Paulo State, where the material was sampled.

Type Material. Holotype: a dissected male ( MZUSP 40292 ) with valves dried and coated for scanning electron microscopy stored in a micropaleontological slide and appendages mounted in a sealed slide with glycerin.

Allotype: a dissected female ( MZUSP 40293 ) stored like the holotype.

Paratypes: two males ( MZUSP 40298 , MZUSP 40299 ) and a female ( MZUSP 40300 ) dissected and stored like the holotype ; two males ( MZUSP 40295 , MZUSP 40297 ) and two females ( MZUSP 40294 , MZUSP 40296 ) dried and coated for scanning electron microscopy stored in micropaleontological slides .

Type Locality. Tank-bromeliads from Parque Estadual Serra do Mar , Núcleo Picinguaba , Ubatuba, S „o Paulo, Brazil. Approximated geographic coordinates: 23º20′27.0″ S, 44º50′14.6″ W. Material collected on Feb. 19, 2003, by Ricardo L. Pinto and Carlos E. F. Rocha .

Description of the male.

Measurements. Male. L: 655 µm; W: 432 µm; H: 317 µm.

Carapace ( Fig. 9A–C ). Small-sized. Surface with sparse setae, normal pore canals and subtle ornamentation. In dorsal view, posterior and anterior ends acuminated: carapace symmetric. In ventral view, surface flat on central portion. In right lateral view carapace greatly elongated (height/length ratio = 0.5), with anterior and posterior margins narrowly rounded; left valve overlapping right one along all margins; dorsal margin slightly arched and ventral margin straight; external flange present, but not well-developed.

Left valve ( Fig. 9E–G ). In internal view with flange present along anterior, ventral and posterior margins, discontinued by bow funnel-shaped structure in oral region; posterior flange extremely narrow. Selvage outstanding, forming narrow bow funnel-shaped structure. Calcified inner lamella and vestibules narrow in both, anterior and posterior regions.

Right valve ( Fig. 9H–J ). In internal view with flange greatly evident along antero-ventral margin, evident along ventral and postero-ventral margins; posterior part with sparse pseudochaetae. Selvage present forming bow funnel-shaped structure in oral region. Calcified inner lamella and vestibules narrow in both anterior and posterior regions. Hinge bar long (slightly longer than 2/3 of length of dorsal margin) and thin; anterior and posterior teeth thin, posterior one being much more developed than anterior one.

Hemipenis ( Fig. 11D ). With broad, rounded and sclerotized muscular body. Main appendage elements: copulatory complex (cop plus LR) and DL; cop without differentiation of distal glans and ejaculatory duct, hooklike, relatively short and tapering towards apex. LR short, with broad basis and acuminated apex. DL elongated (basis width/lobe length ratio = 0.35), acuminate apex and basal digital expansion short and pointed; ds thin and short; fl with two setae and numerous pseudochaetae.

Other appendages as in Elpidium oxumae n. sp. ( Figs. 10A, B, D–F , 11A–C ).

Description of female.

Measurements. L: 686 µm; W: 488 µm; H: 329 µm.

Carapace ( Fig. 12A–D ).Small-sized (L =686 µm).Sexual dimorphism subtle, with posterior contour acuminated. In dorsal and ventral views, major width displaced posteriorly due to externally visible brooding chamber. Ventral surface flat in central portion. In right lateral view, carapace elongated, dorsal and ventral margins straight; left valve overlapping right one along all margins; external flange subtle.

Antenna, terminal segment ( Fig. 10C ). Similar to equivalent in males, but terminal segment with vestigial seta, hyaline formation and three biserrate claws instead of two biserrate claws and one pectinate claw as in males.

Abdomen ( Fig. 11E ). Female end of body rounded and large, with spine-like seta, genital and furcal lobes. Spine-like seta stiff, in dorso-medial position; gl rounded, rigid with trabeculae internally; fl rounded but not rigid, with three equal-length, pappose setae and numerous pseudochaetae.

Other appendages as in Elpidium oxumae n. sp. ( Figs. 10A, D–F , 11A–C ).

Differential diagnosis. Elpidium picinguabaense n. sp. is close to E. merendonense in terms of carapace morphology. Elpidium picinguabaense n. sp. and E. merendonense exhibit equivalent height/length ratios (L/H = 0.5), similar sizes (600 µm–700 µm range) and males and females with similar posterior contours. On the other hand, E. merendonense exhibits two small ventrolateral ridges, a trait absent in E. picinguabaense n. sp. Besides this, E. merendonense has a marked asymmetry on the carapace (particularly visible in females in right lateral view), while the new species described here is symmetric. Additionally, Elpidium picinguabaense n. sp. shows a pronounced external flange, which is absent in E. merendonense . Concerning sexual appendages, the hemipenis of these two species also share similarities. However, they can be differentiated by the shape of the LR (acuminated in E. picinguabaense n. sp. and rounded in E. merendonense ), the cop (longer in E. merendonense ) and the unique E. merendonense DL with a pronounced digital expansion.

Distribution. The species is currently known solely from tank-bromeliads in the type locality.

Figures

FIGURE 9. Elpidium picinguabaense n. sp., male, carapace. A—dorsal view (paratype, MZUSP 40295); B—ventral view (paratype, MZUSP 40295); C—right lateral view (paratype, MZUSP 40295); D—right lateral view, detail of antero-ventral region, showing external flange and ornamentation (paratype, MZUSP 40295); E—left valve, internal view (holotype, MZUSP 40292); F—left valve, internal view, detail of antero-ventral region (holotype, MZUSP 40292); G—left valve, internal view, detail of postero-ventral region (holotype, MZUSP 40292); H—right valve, internal view (holotype, MZUSP 40292); I—right valve, internal view, detail of antero-ventral region (holotype, MZUSP 40292); J—right valve, internal view, detail of posteroventral region (holotype, MZUSP 40292). Scale bars: A–C, E, H—200 µm; D—50 µm; F, G, I, J—100 µm.

FIGURE 10. Elpidium picinguabaense n. sp., A, B, F, male, C–E, female, appendages. A—antennula (holotype, MZUSP 40292); B—antenna (holotype, MZUSP 40292); C—antenna, terminal segment (paratype, MZUSP40300); D—mandible, coxa (allotype, MZUSP 40293); E—mandible, palp (allotype, MZUSP 40293); F—maxillula (holotype, MZUSP 40292). Scale bars: A, B, E—0.05 mm; C, D—0.03 mm; F—0.1 mm.

FIGURE 11. Elpidium picinguabaense n. sp., A–D, male, E, female, appendages. A—first thoracic limb (holoype, MZUSP 40292); B—second thoracic limb (holoype, MZUSP 40292); C—third thoracic limb (holoype, MZUSP 40292); D—hemipenis (holoype, MZUSP 40292); E—abdomen (paratype, MZUSP 40300). Scale bars: A–C—0.05 mm; D, E—0.1 mm.

FIGURE 12. Elpidium picinguabaense n. sp., female, carapace. A—dorsal view (paratype, MZUSP 40294); B—dorsal view, detail of anterior region (paratype, MZUSP 40294); C—ventral view (paratype, MZUSP 40294); D—right lateral view (paratype, MZUSP 40294); E—left valve, internal view (allotype, MZUSP 40293); F—left valve, internal view, detail of antero-ventral region (allotype, MZUSP 40293); G—left valve, internal view, detail of postero-ventral region (allotype, MZUSP 40293); H—right valve, internal view (allotype, MZUSP 40293); I—right valve, internal view, detail of antero-ventral region (allotype, MZUSP 40293); J—right valve, internal view, detail of postero-ventral view (allotype, MZUSP 40293). Scale bars: A, C, D, E, H—200 µm; B—50 µm; F, G, I, J—100 µm.