Paramoebidium santanderensis D.E. Baron & L.G. Valle., 2018

Barón, Daniel E. & Valle, Laia Guàrdia, 2018, First record of trichomycetes associated with aquatic insects from Colombian Moorland and Andean forests, Phytotaxa 361 (1), pp. 1-24 : 4-7

Paramoebidium santanderensis D.E. Baron & L.G. Valle. sp. nov. ( Figs 12–16 )

Mycobank MB 825123

Type:— COLOMBIA. SANTANDER: California; Río San Francisco, 7°21’16.15”N, 72°57’23.05”W, 1966 m., 8-May-2016., D. Baron, prepared from Camelobaetidius sp. ( Ephemeroptera ) nymphs, Microscope slides FH-COL8–Tr21 (Holotype here designed, FH!), COL 8–Tr58 (isotype, BCB!).

Diagnosis: Paramoebidium santanderensis is characterized by the presence of a prominent terminal papilla, with an angular insertion in relation to the main thallial axis, which is straight.

Description:—Thalli unbranched, cylindrical and straight, measuring 35–75 × 4.5–8 μm, with a conspicuous discoid holdfast, 2.4–5.3 μm diam ( Figs 12, 14-16 ). Prominent elongated terminal papilla (spore mother-cell), 8–18.5 × 4.6– 7.4 μm, persistent, retaining the characteristics of the cystospore that originated the thallus, commonly delimited by an abrupt constriction ( Figs 12, 14, 16 ). Cystospores elongate, 7.5–18 μm ( Fig. 13 , arrow). Cysts and amoeba not observed. Attached to the hindgut lining of Camelobaetidius ( Baetidae ) sp. nymphs ( Fig. 13 ).

FIGURES 17–19. Genistellospora homothallica , from Simuliidae . 17. Thallus overview with trichospores. 18. Details of the zygosporophore (zp), Intermediate cell (ic) with thumb-like branch and terminal cell (tc). 19. Thallial branches from the basal cell, and discoid holdfast (arrows). Scale bar for Figs 12–16 , 18, 19 = 25 μm; for Fig. 17 = 50 μm.

Etymology:— Santanderensis, From the province of Santander ( Colombia).

Comments: — Young Thalli of Paramoebidium ecdyonuridae L.G. Valle have similar characteristics, particularly for the presence of the terminal papilla (more discrete in P. ecdyonuridae ), and the cylindrical and relatively straight thallus, which becomes bent when mature (Valle 2014). However, in Paramoebidium santanderensis , the papilla should rather be called spore mother-cell, since it is the persistent cystospore which originated the thallus after germination. This phenomena is common in Eccrinales (the spore mother-cell being the sporangiospore), but not in Amoebidiales ( Lichtwardt 1986). P. santanderensis has a discoid holdfast slightly narrower than the corresponding thallus, while being drastically tapered in Paramoebidium ecdyonuridae (Valle 2014) . This is the first record of Paramoebidium (and trichomycetes) from Camelobaetidius Demoulin , a Panamerican genus of small minnow mayflies widely distributed in South America ( Salles & Serrão 2005). A recently described species, Paramoebidium lateralis L. Busquets & L.G. Valle , can be differentiated from the new species described here by thallus structure and lateral holdfast, but may also retain the cystospores, observable as a spore-mother cell after thallial growth ( Busquets et al., 2018).

Figures

FIGURES 12–16. Paramoebidium santanderensis from Baetidae.12. Cylindrical thallus, with a basal discoid holdfast (arrow), attached to hindgut lining. 13. One cystospore in the bottom (arrow) before germination, the other (arrowhead) after germination. 14–16. Cystospores (spore mother-cells), after germination, which remain attached to the apex of the growing thallus.