4. GERTRUDIELLA Plate 5.

Gertrudiella Broth., Nat. Pfl. ed. 2, 11: 528, 1925. Type: Gertrudiella validinervis (Herz.) Broth.

Gertrudia Herz., Biblioth. Bot. 87: 44, 1916, hom. illeg. non K. Schumann, 1900. Type: Gertrudia validinervis Herz.

Plants in cushions, green above, brown to red-brown or blackish-brown below. Stems branching occasionally, to 2.0 cm in length, transverse section rounded-pentagonal to elliptical, central strand very strong and well differentiated, sclerodermis present, hyalodermis present but firm-walled; axillary hairs of 5–7 clear cells. Leaves crowded, weakly spreading, weakly to strongly contorted or curled when dry, squarrose from a short, sheathing base when moist, lanceolate, 3.5–4.5 mm in length, upper lamina broadly channeled across leaf, margins strongly revolute to near apex, entire or occasionally weakly dentate near apex; apex narrowly acute, occasionally narrowly obtuse; base long-elliptical; costa percurrent to excurrent as a short, denticulate awn, superficial cells quadrate ventrally, elongate dorsally, 10–15 rows of cells across costa ventrally at midleaf, costal transverse section semicircular, stereid band single, strong and reniform, epidermis of 1 layer of strongly hollow-papillose cells ventrally, epidermal cells weakly developed dorsally, guide cells 15–20 in 3–4 layers, hydroid strand present; upper laminal cells subquadrate to irregularly hexagonal, small, 8–10 µm in width, 1:1, walls evenly thickened, superficially bulging-mamillose ventrally, flat dorsally in medial portion of lamina, bulging on both sides in 10–20 rows marginally; papillae present on marginal cells, low, simple, hollow; basal cells differentiated medially, rectangular, little wider than the upper, 3–4:1, walls thin, occasionally transversely slit across longitudinal walls. Apparently dioicous. Perichaetia unknown. Perigonia appearing as axillary buds near stem apex, inner leaves deltoid, outer leaves elongate. Sporophyte unknown. Laminal KOH color reaction orange.

Rare, restricted to Bolivia where it has been collected on stone in rather dry areas, at low to high (300–3200 m) elevations.

This monotypic genus is well characterized, mainly by the ventrally mamillose medial cells of the lamina, several rows of marginal cells bulging on both sides and low-papillose, epidermal cells on the ventral surface of the costa numerous and strongly hollow-papillose, and guide cells rather thick-walled and forming a multilayered cylinder (Pl. 5, f. 7). Hilpert (1933) included Trichostomum ferrugineum Herz. in Gertrudiella on account of the several layers of guide cells. This species is actually a Didymodon (with much the same general appearance of D. occidentalis of western North America) by the orange reaction to KOH, lanceolate leaves deeply and widely channeled ventrally along the stout costae, and upper laminal margins bistratose, and is here treated as Didymodon herzogii (nom. nov. in treatment of Didymodon), differing from related taxa of sect. Vineales by the microstomous, eperistomate capsule and medial basal cells transversely resorbed across longitudinal walls to form slits. The last character has also been described for Kingiobryum Robins. (see Zander & Cleef 1982) of the Dicranaceae. Although G. validinervis shows some slitting of basal laminal cells, it and D. herzogii are not closely related. Kingiobryum, which is eperistomate, may well belong to the Pottiaceae; further study is needed.

Gertrudiella shares several characters with various species of Pseudocrossidium, among them revolute margins, differentiation of medial upper laminal cells (especially P. leucocalyx) and presence of ventral costal epidermal cells, a single stereid band, guide cells in more than one layer, and small upper laminal cells. It is, however, apparently not closely related. Streptocalypta has a similar arrangement of thick-walled guide cells but has quite different areolation. The guide cell cylinder of Gertrudiella is probably mainly of structural importance; sections reveal that there is no direct connection with the equally well-differentiated stem central strand (Pl. 5, f. 2).

Biblography: Herzog (1916), Hilpert (1933).

Number of accepted species: 1.

Taxa examined: G. validinervis (BUF and isotypes at JE, L, W), G. validinervis var. serratopungens (JE, L).

New combination: Gertrudiella validinervis (Herz.) Broth. var. serratopungens (Herz.) Zand., comb. nov. (Gertrudia validinervis Herz. var. serratopungens Herz., Biblioth. Bot. 87: 45, 1916).