Monographs Details: Comarostaphylis discolor subsp. manantlanensis Diggs
Authority: Luteyn, James L., et al. 1995. Ericaceae, Part II. The Superior-Ovaried Genera (Monotropoideae, Pyroloideae, Rhododendroideae, and Vaccinioideae P.P.). Fl. Neotrop. Monogr. 66: 560. (Published by NYBG Press)
Family:Ericaceae
Description:Subspecies Description - Terrestrial, multi-trunked, erect shrubs to 2.5 m tall; capable of sprouting after fire damage; bark shredding, dark gray to nearly black; young twigs ferruginously tomentulose, the trichomes eglandular, a few individuals with small scattered glandular trichomes, bark on young twigs shedding, orangish underneath. Leaves clustered near the stem tips, fewer present on the lower branches, coriaceous, narrowly ovate to broadly elliptic, to 17.7 × to 5.3 cm, base cuneate to tapering, apex acute, margins serrulate, plane or very slightly revolute, upper surface glabrous or sparsely tomentulose when young, lower surface ferruginously tomentulose, sometimes densely so, becoming less so with age (very young leaves canescent); petioles to 15 mm long, indumentum as on young twigs. Inflorescences paniculate, to 17 cm long, sometimes with reddish coloration; rachis, pedicels, bracts, bracteoles, and calyx lobes glandular hirtellous, the trichomes stalked, swollenheaded and glandular, to ca. 1 mm long; floral bracts glandular ciliate, bracteoles glandular ciliate. Flowers with calyx lobes triangular, to ca. 2 × 1.3-1.5 mm, glandular ciliate, green to pink or red; corollas 4.5-6 × ca. 3 mm, externally sparsely pubescent by eglandular hyaline trichomes, yellow-cream to white or light green, sometimes tinged with pink or red while in bud. Fruit red when immature, black at maturity.

Discussion:During a revision of Comarostaphylis (Diggs, 1981), I decided, on the basis of the specimens at hand, that the pubescent-leaved individuals (five collections) from the Sierra de Manantlan of Jalisco were hybrids between C. discolor subsp. discolor and C. longifolia. Several collections of typical subsp. discolor were known from the area, and C. longifolia was known from the nearby Nevado de Colima. The Manantlan individuals resemble C. discolor subsp. discolor in most characters, but approach C. longifolia in having pubescence on the undersurfaces of the leaves, quite variable leaf size, and inflorescences with abundant glandular trichomes. A few individuals even have small scattered glandular trichomes (never abundant) on the petioles and young twigs, hinting of a relationship with C. longifolia, which is known for its densely glandular hirsute twigs and petioles.

However, population collections made by S0ren-son et al. in 1980, and field work at the type locality in the summer of 1986, have convinced me that these populations are a distinct subspecies of C. discolor. Thus, there are two sympatric, but ecologically distinct, subspecies of C. discolor in the Sierra de Manantlan. During early June 1986, nearly all individuals (hundreds) of subsp, manantlanensis were in full bloom, while only one individual in the large sympatric population of subsp. discolor was found with flowers. Additionally, subsp. discolor was confined primarily to exposed sites, usually in full sun, while subsp, manantlanensis was found more frequently under Pinus sp. and in the frequently burned forests near the summits. Subspecies manantlanensis also differs in general aspect, being readily recognizable at some distance. The darker stems, leaves more clustered at the stem tips, and fewer leaves on the lower branches all serve to give it a rather different gross appearance from subsp. discolor.

The clearest morphological character separating subsp. manantlanensis from subsp. discolor is the rather dense eglandular pubescence on the lower leaf surfaces, petioles, and young twigs (vs. glabrous in subsp. discolor). Subspecies manantlanensis is also characterized by abundant glandular trichomes on the inflorescences. which cause the inflorescences to feel quite sticky to the touch and also frequently entrap small insects. These inflorescence trichomes clearly distinguish subsp. manantlanenis from the other pubescent-leaved subsp. of C. discolor, subsp. rupestris, which has only eglandular inflorescence trichomes and is endemic to Michoacan.

Subspecies manantlanensis is distinguished from C. longifolia by the lack of glandular trichomes (or scattered glandular trichomes to ca. 1 mm long) on the petioles and young twigs (vs. abundant glandular trichomes to ca. 4 mm long); more abundant ferruginous tomentulum on the lower leaf surfaces; lack of enlarged floral bracts in the inflorescences; typically smaller leaves; and much shorter glandular trichomes in the inflorescences.

The evolutionary origin of subsp. manantlanensis is unclear. The subspecies may simply represent local differentiation within C. discolor in the isolation of the Sierra de Manantlan. However, hybridization between C. discolor subsp. discolor and C. longifolia may have occurred in the past.

Subspecies manantlanensis represents one of the many endemics, including Zea diploperennis (Iltis et al., 1979), found in the newly established Reserva Biosfera de la Sierra de Manantlan (Diggs, 1988).

Distribution and Ecology: Comarostaphylis discolor subsp. manantlanensis is confined to the the Sierra de Manantlán in SW Jalisco, Mexico, and occurs in Pinus, Pinus-Quercus, and Pinus-Quercus-Abies forests at 2500-3000 m elevation. It typically occupies summit forests, thickets, and steep slopes and is frequently found in areas of recurrent fire. Individuals stump sprout following damage by fire. Associates include Arbutus occidentalis, A. xalapensis, Castillejo macvaughii, Cupressus lindleyi, Eryngium sp., Montanoa sp sp., and Senecio sp. Flowering Jan-Jul; fruiting Jan-Apr-? (Diggs, 1988). Preliminary pollination studies were carried out in Jun 1986 at the type locality. Observations were made during a complete dawn-to-dusk cycle on two individuals. A total of 92 visitors were observed, 69 (75%) of these being bumblebee type Hymenoptera and 23 (25%) being Lepidoptera (small butterflies). The bumblebees were active throughout the day beginning almost immediately after sunrise (ca. 6 A.M.) with the fewest visits between 11 A.M. and 2 P.M. (6 of 69 visits), while Lepidoptera visit was most common between 11 A.M. and 2 P.M. (10 of 23 visits). Bumblebees visited an average of 3.8 inflorescences (range 1-19) and spent an average of 2 min. 38 sec. per trip to the plants, while Lepidoptera visited an average of 3.2 inflorescences (range 1-7) and spent an average of 5 min. 17 sec. per trip to the plants. While Lepidoptera averaged more time per visit, much of this time was spent resting quietly, while nearly 100% of the time spent by bumblebees was in active foraging on the inflorescences. An indication of this is the greater number of inflorescences visited per trip by the bees even though their visits were, on average, shorter.

Distribution:Mexico North America| Jalisco Mexico North America|