Elpidium eriocaularum, 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 : 20-24

Elpidium eriocaularum n. sp.

Figs. 13–15

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Diagnosis. Small-sized Elpidium (length of male left valve = 683 µm; length of female left valve = 737 µm). Carapace elongated (height/length ratio = 0.6). Surface brownish with sparse setae, normal pore canals and subtle ornamentation. Left valve overlapping right one. Hinge bar long (longer than 2/3 of dorsal margin length); anterior and posterior proto-teeth thin and smooth. Copulatory process on hemipenis without differentiation of distal glans and ejaculatory duct, hook-like. Lower ramus with broad basis and tapered apex. Distal lobe elongated (basis width/ distal lobe length ratio = 0.3) with acuminated apex, medial digital expansion short and pointed.

Etymology. The first species of the genus Elpidium ever described was named Elpidium bromeliarum , referring to its then peculiar occurrence within plants of Bromeliaceae . Likewise, we name the present species Elpidium eriocaularum in allusion to its finding within plants of Eriocaulaceae . It is thus far the first Elpidium species described from a phtytotelm other than bromeliad plants.

Type Material. Holotype: a dissected male ( MZUSP 40301 ) with valves dried and coated for scanning electron microscopy stored in a micropaleontological slide and appendages mounted in a sealed slide with glycerin.

Allotype: dissected female ( MZUSP 40302 ) stored like the holotype.

Paratypes: four males ( MZUSP 40303 , MZUSP 40304 , MZUSP 40306 , MZUSP 40307 ) and three females ( MZUSP 40305 , MZUSP 40308 , MZUSP 40309 ) dissected and stored like the holotype .

Type Locality. Water accumulated among leaves of the plant Eriocaulon sp. from Estaç „o Ecológica de Angatuba , Angatuba, São Paulo, Brazil. Approximated geographic coordinates: 23º24′41.6″ S, 48º19′30.0″ W. Material collected on Oct. 03, 2002, by Carlos E. F. Rocha and Ricardo L. Pinto .

Description of the male.

Measurements. L (of left valve): 683 µm; H (of left valve): 393 µm.

Carapace (not illustrated. After fixation, no specimens were preserved with closed carapace, which prevented its description).

Left valve ( Fig. 13A–C ). In internal view with flange narrow along antero- and postero-ventral margins, discontinued along ventral margin; with sparse setae in postero-ventral region. Selvage well marked along anterior, ventral and posterior regions, forming narrow bow funnel-shaped in oral region. Calcified inner lamellae and vestibules narrow on both anterior and posterior region.

Right valve ( Fig. 13D–F ). In internal view with flange present along anterior, ventral and posterior margins, discontinued briefly by bow funnel-shaped structure; posterior part with sparse setae. Selvage well marked along anterior, ventral and posterior margins, forming bow funnel-shaped structure in oral region. Calcified inner lamellae narrow in anterior region, extremely narrow in posterior region. Vestibule narrow in both anterior and posterior regions. Hinge bar long (length superior to 2/3 of length of dorsal margin), with anterior and posterior proto-teeth thin and smooth.

Hemipenis ( Fig. 15D ). With a 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, short, gently tapering from basis to apex. LR with basis globular and apex narrow and acuminated. DL large and rather elongated (basis width/distal lobe length ratio = 0.3), with acuminated apex and medially pointed digital expansion; ds slender, almost reaching mid-length of DL; fl with pair of setae and numerous pseudochaetae.

Other appendages as in Elpidium oxumae n. sp. ( Figs. 14A, B, D, E , 15A–C ).

Description of female.

Measurements. L (of left valve): 737 µm; H: 422 µm.

Left valve ( Fig. 13G–I ). In internal view with flange present along antero- and postero-ventral margins, discontinued along ventral margin; posterior flange extremely narrow. Selvage well marked along anterior and posterior margins, running along ventral valve margin; narrow bow funnel-shaped structure in oral region. Calcified inner lamellae and vestibules narrow in both anterior and posterior regions.

Right valve ( Fig. 13J–L ). In internal view with flange on anterior, ventral and posterior regions, discontinued briefly by the bow funnel-shaped structure; posterior portion with sparse setae. Selvage well marked on anterior, ventral and posterior regions, forming bow funnel-shaped structure on oral region. Calcified inner lamellae and vestibules narrow on both anterior and posterior region. Hinge bar long (length superior to 2/3 of dorsal margin length). Anterior and posterior proto-teeth thin and smooth.

Antenna terminal segment ( Fig. 14C ). Similar to equivalent in males, but terminal segment with vestigial seta, hyaline formation and three biserrate claws instead of two biserrate and one pectinate claws.

Abdomen ( Fig. 15E ). Female end of body rounded and large with spine-like seta, genital lobes 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. 14A, D, E , 15A–C ).

Differential diagnosis. Elpidium eriocaularum n. sp. is a small and relatively elongated species. The cop is similar to that of E. bromeliarum : short, hook-like and without differentiation of distal glans and ejaculatory duct, however, less evenly curved than that of E. bromeliarum . Furthermore, the LR of E. eriocaularum n. sp. differs by its more globular basis and pointed apex, while the DL has more acuminated tip.

Distribution. The species is currently known solely from Eriocaulun sp. phytotelms in the type locality.

Figures

FIGURE 13. Elpidium eriocaularum n. sp., A–F, male, G–L, female, carapace.A—left valve, internal view (holotype, MZUSP 40301); B—left valve, detail of anterior region (holotype, MZUSP 40301); C—left valve, internal view, detail of posterior region (holotype, MZUSP 40301); D—right valve, internal view (holotype, MZUSP 40301); E—right valve, detail of anterior region (holotype, MZUSP 40301); F—right valve, detail of posterior region (holotype, MZUSP 40301); G—left valve, internal view (allotype, MZUSP 40302); H—left valve, detail of anterior region (allotype, MZUSP 40302); I—left valve, detail of posterior region (allotype, MZUSP 40302); J—right valve, internal view (allotype, MZUSP 40302); K—right valve, detail of anterior region (allotype, MZUSP 40302); L—right valve, detail of posterior region (allotype, MZUSP 40302). Scale bars: A, D, G, J—200 µm; B, C, F, H, I, K, L—100 µm; E—50 µm.

FIGURE 14. Elpidium eriocaularum n. sp., A, B, D, E, male, C, female, appendages.A—antennula (paratype, MZUSP 40306); B—antenna (paratype, MZUSP 40304); C—antenna, terminal segment (allotype, MZUSP 40302); D—mandible (holotype, MZUSP 40301); E—maxillula (holotype, MZUSP 40301). Scale bars: A–E—0.05 mm.

FIGURE 15. Elpidium eriocaularum n. sp., A–D, male, E, female, appendages. A—first thoracic limb (paratype, MZUSP 40303); B—second thoracic limb (paratype, MZUSP 40304); C—third thoracic limb (holotype, MZUSP 40301); D—hemipenis (holotype, MZUSP 40301); E—abdomen (allotype, MZUSP 40302). Scale bars: A–C—0.05 mm; D, E—0.1 mm.