Mitthyridium repens

Mitthyridium repens

Range Map

This clade is one of the more common in Mitthyridium and consists of numerous unique lineages from Australia, Singapore, Borneo, & Peninsular Malaysia; most commonly found on trees.

Description

Lineage: Mitthyridium repens

Latin name: Mitthyridium repens (Harv.) Robinson
Synonyms:
Syrrhopodon repens
Syrrhopodon humile
Syrrhopodon lousiadum
Thyridium lousiadum
Mitthyridium louisiadum
Thyridum parvifolium
Mitthyridium parvifolium
Syrrhopodon unulatulus
Thyridium undulatulum
Mitthyridium undulatulum
< specimens examined 290 274 387 388 401 344 396 275 378 379 276 289 382 393 807>

General features:
Plants small, flat green to yellow-green in color. Branches short and densely foliate, rarely longer than 1 cm (more commonly around 0.5 cm) and forming dense mats or tufts that are low and tightly affixed to the substrate. Leaves flared at shoulders and rarely more than 1-1.5 mm in length, 0.5 mm long at the widest section. Sharp, large marginal teeth common especially around the shoulders. Sporophytes frequent, seta 3-5 mm long. Gemmae arising from the adaxial tip of the costa present when sporophytes are not.

This is one of the most common taxa of Mitthyridium in South East Asia. It is easy to recognize by its small size, short branches, crispate leaves, and marked serrations along the leaf margins. The group is also one of the largest in Mitthyridium consisting of numerous unique lineages from Australia, Singapore, Borneo, Peninsular Malaysia, etc.

Diagnostic phylogenetic characters: [move the cursor over the image to view the morphological matrix]:
On average members of repens have 11 cell columns on each side of the midrib. The cancellinae/laminar transition shape is often 4. The number of border cell columns is few, on average 6-7. The margin tapers at approximately 1/2 the leaf length. The leaf apex is very commonly mucronate.

Diagnostic phylogenetic characters (synapomorphies and/or autapomorphies) were assessed by optimizing via ACCTRAN morphological characters to the 80 taxon total evidence phylogeny decribed in the Phylomonography&Mitthyridium section bulleted above.

Gemmae variably present or absent
Gemmae are rough.
Gemmipars unknown.
Cancellinae – on average 11 cell columns on each side of the midrib.
Cancellinae composed on average 1/4 the total leaf length.
Transition shape between lamina and cancellinae 4 or 5.
Large marginal serrrations present.
Margin serrations cover the majority of the leaf, most marked at the shoulders.
Margin tapers from 4 to 2 cells thick at 1/2 of the leaf length measured from the apex.
Hyaline border - on average, 0-7 marginal border cell columns.
Margin more or less flat and unistratose.
Leaf apex mucronate.
Leaf tip rhizoids often present.
Leaf base rhizoids typically absent.
Leaves not undulate.
Papillae present on laminal cell sufaces.
Papillae do not obscure the cell outlines in transverse sectional view.
Two or more papillae per laminal cell.
Papillae absent on adaxial surface of costa.
Adaxial epidermis often present.
Abaxial epidermis weak or not present.
Adaxial stereid band present.
Abaxial stereid band present.
Costa shape elliptical.
Autapomorphies (diagnostic characters): 5, 11