Lomas formations are highly endemic plant communities occurring in near-shore locations of Peru and Chile where ocean fog provides sufficient moisture for the development of vegetation (nearly verbatim from Dillon 2005). "Each locality is an island of vegetation among a virtual ocean of arid desert, ..." (Dillon 2005). In the genus Jaltomata there are six or seven species that grow in this habitat.

Biogeography: The Jaltomata species of the lomas are not a monophyletic group (Miller, Mione et al. submitted manuscript). In general, the closest relatives of these species are Andean members of this genus. Jaltomata lomana, J. hunzikeri, J. truxillana, and a new species from department Arequipa are endemic to lomas and known from a single locality. Jaltomata lomana is rare and hard to find on the one small coastal mountain on which it grows. Segundo Leiva, Leon Yacher and I searched for J. hunzikeri at its type locality and we could not find it, despite despite success in fieldwork with this genus ordinarily. Jaltomata truxillana is endemic to Cerro Campana, a small isolated near-shore mountain, and fewer than 40 plants exist. Jaltomata umbellata and J. aspera appear not to be in imminent danger of extinction. Jaltomata aspera is the only member of the genus growing both in the Andes and in the lomas, with plants of the Andes flowering at a different time of the year than the plants of the lomas.

These six or so Jaltomata species grow in small islands of suitable habitat (lomas) from northern Peru to Southern Peru. More specifically, these species range from Department La Libertad at about 8 degrees South latitude to Department Arequipa at about 15 45' degrees South latitude, a span of roughly 888 km. North to south, the first two species, J. truxillana and J. lomana, are about 189 km away from each other. And from J. lomana to J. hunzikeri is another approximately 222 km. Thus, the Jaltomata species of the lomas are widely separated from each other, and are generally closer to the Andes than to each other. Jaltomata umbellata and J. aspera are an exception: These two species grow in the same region and have even been collected in the same lomas formation (Amancaes). Interestingly, these two species seem the least likely to compete for pollinators because J. umbellata has a tubular corolla and J. aspera has a satellite-dish shaped corolla.

What is the explanation for this geographic distribution? I can think of two non-mutually exclusive possibilities:
1) Separate dispersal events from (or to?) the Andes, with populations originally small and therefore subject to genetic drift/bottlenecks, and likely subjected to selection by new pollinators and new abiotic factors.
2) Vicariance: perhaps there was more widespread suitable habitat for Jaltomata in the past, and (gradual and fluctuating?) drying separated the few coastal habitats (lomas) from the higher Andes that are still suitable for growth of the genus. As mentioned, J. aspera grows both in the lomas and in the Andes, and at present we do not have data that shows whether the high altitude plants are ancestral to the lomas plants, if the lomas plants are ancestral to the high altitude plants, or if the lomas and the high altitude plants are the remnants of a once wider distribution for this species.

Islands: All of the above species may be viewed as growing on virtual islands. Two additional Jaltomata species grow on oceanic islands, J. antillana (Greater Antilles) and J. werffii (Galápagos Islands).

Deciduous: Jaltomata truxillana (Cerro Campana, Department La Libertad) is deciduous, dropping its leaves for the dry season. Jaltomata umbellata appears not to be deciduous: I visited a population at Reserva Nacional de Lachay in June of 2005 during a drought and plants had leaves! Whether or not the other species are deciduous is unknown.

Red-Orange Nectar: Jaltomata aspera, J. umbellata and a specimen collected by Weigend in department Arequipa produce red-orange nectar. Click here for a table of Jaltomata species having red to orange nectar.

Endemism: At least four of the five to six species are endemic to the lomas; see table for details.

Which Months Are These Species In Flower?: In the lomas, all of these species bloom in September/October. See above table for clarification and details.

Key to the Jaltomata of the Peruvian lomas formations:

1. Herbaceous but perhaps woody at base; corolla broadly campanulate (not tubular), nectar red . . 2

1. Shrubs; corolla short-tubular with a limb, green to white, nectar clear or red . . . . . . . . . . . . . . . 3

2. Having 10 green corolla maculae, the corolla purple . . . . . . . . . . . . . . . . . . . . unpublished (Arequipa, Peru)

2. Lacking corolla maculae, the corolla green-yellow or yellow-green . . . J. aspera

3. Corolla tube at least 6.5 mm long and containing red nectar . . . . . . . . . . . . . . . J. umbellata

3. Tubular part of the corolla less than 6.5 mm long, lacking red nectar . . . . . . . . . . . . . . . . . . 4

4. Corolla with blue ring in tube; young axes, petioles, peduncles, pedicels, and abaxial face of calyx villous J. hunzikeri

4. Corolla tube lacking blue ring; axes and leaves glabrous or nearly so . . . . . . . . . . . . . . . . . . . . . . 5

5. Corolla white, the limb spreading (not planar); stamens included . . . . . . . . . . . . . . . J. lomana

5. Corolla limb lavender near tube, fading to white toward margin of limb, the limb planar; stamens exserted . . . . . J. truxillana