40. MOLENDOA Plate
53.
Molendoa Lindb., Utkast
Nat. Grupp. Eur. Bladmoss. 29, 1878. Type: Molendoa hornschuchiana
(Hook.) Lindb. ex Limpr.
Pleuroweisia Limpr. ex
Schlieph., Flora 68: 359, 1885. Type: Pleuroweisia schliephackei Limpr. ex
Schlieph.
Ozobryum Smith Merrill,
Novon 2: 255, 1992. Type: Molendoa ogalalensis (Smith Merrill) Zand.
Anoectangium subg. Molendoa
(Lindb.) Kindb., Eur. N. Amer. Bryin. 2: 317, 1897.
Plants in a compact turf, dark to light green, occasionally
glaucous above, brown, often tan below. Stems branching seldom to often, to
4.0 cm in length, transverse section rounded-triangular to pentagonal, central
strand present, usually strong, sclerodermis present, usually weak, hyalodermis
absent or occasionally weakly developed; axillary hairs of 315 cells, usually
all hyaline or occasionally basal 12 cells thick-walled; light brown to
reddish tomentum sometimes present. Leaves usually crowded, appressed
incurved to weakly spreading, usually twisted, occasionally tubulose when dry,
spreading to spreading-recurved when moist, variously oval, ligulate,
long-oblong, linear, ovate-to linear-lanceolate, (0.3)1.04.0 mm in length,
upper lamina flat to broadly or occasionally narrowly channeled, margins
plane to weakly recurved in lower 1/2, entire or occasionally sinuolate
above, occasionally denticulate at shoulders of the base (when
dilated), upper margins often bistratose entirely or in patches; apex broadly
to narrowly acute, occasionally broadly rounded and somewhat cucullate; base
scarcely differentiated to elliptical and sheathing; costa ending 13(6) cells
below apex, percurrent, or excurrent as a stout mucro, superficial cells
quadrate to elongate on both sides, 27 rows of cells across costa ventrally at
midleaf, costal transverse section circular, semicircular to flattened
reniform, stereid bands absent to weak ventrally, present
dorsally and flattened in section, epidermis present ventrally, usually
present but weak dorsally, guide cells 24(7) in 1 layer, hydroid
strand absent; upper laminal cells often irregular in shape,
rounded-quadrate, oval, rounded-triangular, ca. 810 ΅m in width, 1:1, walls
evenly thickened to weakly trigonous, superficially flat to bulging; papillae
usually crowded, low, irregularly scablike, occasionally
simple to bifid or massively multifid; basal cells differentiated across leaf
or reaching higher along costa or margins, rectangular, little wider than the
upper cells, (1)25:1, walls thin, evenly thickened to porose. Propagula
rarely present, obovoid to spindle-shaped, ca. 3550 ΅m long,
multicellular, borne in leaf axils. Dioicous. Perichaetia terminal on short
lateral branches, inner leaves ovate-lanceolate, often marginally
serrulate, to 3 mm in length, sheathing the seta, lower cells rhomboidal in
lower 1/2 to throughout. Perigonia lateral. Seta 0.20.7 cm in length, 1 per
perichaetium, yellow to brown, twisted clockwise below; theca 0.61.5 mm
in length, yellow‑brown, ovoid to cylindrical, often macrostomous,
exothecial cells thin-walled, stomates phaneropore, at base of theca, annulus
of 23 rows of transversely elongated, hexagonal cells, weakly vesiculose;
peristome teeth absent. Operculum very
long-rostrate, oblique,
ca. 0.81.5 mm in length, cells straight. Calyptra cucullate, smooth, 1.02.5
mm in length. Spores ca. 912 ΅m in diameter, brown, essentially smooth or
weakly to weakly papillose. Laminal KOH reaction light yellow. Reported
chromosome number n = 13.
This genus is found on
all continents except Australia and Antarctica, in montane or arctic areas,
growing mainly on soil or rock (often calcareous) in wet or seasonally moist
places.
Diagnostic characters
are few and somewhat variable. For this reason species of Molendoa are
often confused with Anoectangium species, which also are eperistomate
and pleurocarpous, and also often have triangular stem sections. Molendoa
differs from the latter principally by the presence of a ventral costal stereid
band (Pl. 53, f. 6, 22), which, unfortunately, is often absent in Molendoa
specimens of small size. Other characters that are found in some but not all
species of Molendoa (or which occur only in well-developed populations
of certain species), but which are not found in Anoectangium, may be
used to refer specimens to the correct genus. These occasional indicator
features of Molendoa include glaucous color of the upper leaves,
becoming light tan in lower parts of the plant; leaves linear-lanceolate or not
keeled; apex rounded, not apiculate; upper margins bistratose (Anoectangium
may be bistratose in transverse spaced rows across upper leaf); leaf base much
dilated and shoulders sometimes denticulate; superficial cells of the costa
quadrate; costa ending before the apex or very broad (up to 7 rows of cells
across costa ventrally at midleaf and up to 7 guide cells in the costa); costal
transverse section flattened reniform, or showing two stereid bands; laminal
cells heterogeneous in shape (Pl. 53, f. 14), or superficial walls (as seen in
section) flat and distinctly thicker than the contiguous, anticlinal walls (Pl.
53 6, 22); papillae low, scab-like, crowded; KOH reaction pale yellow (versus
yellow-orange); theca macrostomous (Pl. 53, f. 9).
The leaf shape, leaf section,
and propagula are similar to those of Didymodon (sensu Saito
1975a), but Molendoa differs from that genus by the rather distinctive
scab-like papillae (in most species) and, of course, the lateral gametoecia. Molendoa
clavuligera (not seen) is reported to have clavate leaf apices similar to
those of Didymodon johansenii. Molendoa is, on analysis, more
closely related to Didymodon than to Anoectangium in some
cladograms and is placed in the Hyophileae of the Pottioideae in Cladograms
1416..
Pleuroweisia is here treated as a synonym of Molendoa
(following the suggestion of Hilpert 1933) in that the key characters of the
former are also found in Molendoa. The recognition of the genus Pleuroweisia
by several modern authors (Brotherus 192425; Hilpert 1933; Chen 1941;
Savicz-Ljubiskaja & Smirnova 1970) is probably due to acceptance of
technical characters advanced by Limpricht (1890) that in fact have no
substance. The calyptrae, alleged (Limpricht 1890; Chen 1941) to cover only the
rostrum of the operculum, are also found perched on the rostrum in Molendoa
sendtneriana in both microstomous (e.g. Mexico: Mόller 1834, MICH, type of Anoectangium
glaucescens) and macrostomous (e.g. Mexico: Le Sueur E6a, FH) collections.
The type specimen (leaves figured in Pl. 53, f. 2326 from an isotype,
Switzerland, Pontresina, Roseg-Gletschers, Graf, 9-7-1883, H) of Molendoa
schliephackei (= Pleuroweisia schliephackei) has calyptrae present
only on immature capsules, and, in fact, these partly cover the thecae as well
as the opercula. Other characters, such as the recurved leaf margins, rounded
apex, rather thick-walled laminal cells, indistinct stem central strand, ovoid
perichaetial leaves that sheath the seta, ovoid capsules, and somewhat
vesiculose annular cells are also found in various combinations in Molendoa,
specifically the highly variable (Pilous 1958; Zander 1977c) M. sendtneriana.
The chromosome number of M. schliephackei has been reported (Fritsch
1972) to be the same as that of Molendoa sendtneriana, n = 13.
Characters that may prove of significance for M. schliephackei at
the species level are the strongly recurved laminal margins and the rather
large leaf cells (1214 ΅m in diameter), although these are features seen so
far only in the type specimen. Other specimens examined that were identified as
this species are within the range of variation accepted (Zander 1977c) for M.
sendtneriana in the New World, and none match the type of the species in
all significant respects. Perhaps Geissler (1985) has a better solution to the
problem of variation among these taxa; she viewed M. sendtneriana, M.
schliephackei, M. tenuinerve and M. taeniatifolia as synonyms
of M. hornschuchiana (as Anoectangium hornschuchianum).
Previously placed in Anoectangium,
Molendoa platyphyllum (Pl. 53, f. 1015) of the Peruvian Andes and M.
warburgii (Pl. 53, f. 1618) of the United Kingdom are similar in the small
plant size, much-branched stems, leaf shape (ovate-triangular with a
constricted apex) and costa thin (the former has two stereid bands, but none
have yet been detected in the latter). The two differ in papillae shape (the
former has low, scattered scabs, while the latter has massive simple or less
thickened bifid papillae), but these two species are evidently closely related.
Long (1982c) found propagula in the latter species, and he rightly suggested
these indicate a closer relationship to Molendoa than to Anoectangium.
The mid-North American M. ogalalensis, type of Ozobryum, is
similar to these but differs in the lack of a stem sclerodermis, the broader
leaf apex, single massive papilla over each bulging lumen, and superficial
walls of upper laminal cells not distinctly thicker than the internal walls;
this species is distinctive but, in my opinion, not at the generic level. Molendoa
ogalalensis is similar in stem section, leaf shape and papillae morphology
to Quaesticula navicularis, which differs, however, in the incurved
upper leaf margins and terminal perichaetium.
The Bryotheca E.
Levier specimen of Molendoa roylei at NY is Hymenostylium
recurvirostrum and other distributed duplicates may also be this species. Hymenostylium
characteristically (but not always) lacks a central strand. This and the
rectangular, often irregularly thickened median leaf cells are good
distinguishing characters for sterile specimens.
Additional literature:
Castelli (1966, 1968), Gyφrffy (1910, 1912, 1914, 1946), Herzog (1943),
Iwatsuki & Sharp (1958this paper actually refers to Tuerckheimia
svihlae (Bartr.) Zand. as noted by Saito 1972b and Zander 1979b, both as Tuerckheimia
angustifolia).
Number of accepted
species: 15.
Species examined: M.
duthei (NY), M. hornschuchiana, M. ogalalensis
(BUF), M. platyphyllum (F, NY), M. schliephackei
(BP, H, NY, PC), M. seravschanica (H), M. sendtneriana,
M. warburgii (BUF).
New heterotypic
synonymy: Hymenostylium secundum C. Mόll. = Molendoa sendtneriana
(BSG) Limpr. Hymenostylium validinerve Dix. & P. Varde = Molendoa
sendtneriana (BSG) Limpr.
New combinations: Molendoa
ogalalensis (Smith Merrill) Zand., comb. nov. (Ozobryum
ogalalense Smith Merrill, Novon 2: 255, 1992). Molendoa platyphyllum
(Williams) Zand., comb. nov. (Anoectangium platyphyllum Williams,
Field Mus. Nat. Hist. 4(5): 130, 1927. Molendoa schliephackei (Limpr. ex
Schlieph.) Zand., comb. nov. (Pleuroweisia schliephackei Limpr.
ex Schlieph., Flora 68: 359, 1885 [Pleuroweissia schliephackei Limpr.,
Jahresber. Schles. Ges. Vaterl. Cult. 61: 224, 1884, nom. inval. sin.
descr.]). Molendoa warburgii (Crundw. & Hill) Zand., comb. nov.
(Anoectangium warburgii Crundw. & Hill, J. Bryol. 9: 435, 1977
[1978]).