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 seven species that grow in this habitat.

Biogeography: The Jaltomata species of the lomas are not a monophyletic group (Miller et al. 2011). In general, the closest relatives of these species are Andean members of this genus.

Jaltomata atiquipa, J. hunzikeri, J. lomana and J. truxillana 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 success in fieldwork with this genus ordinarily. Jaltomata truxillana is endemic to Cerro Campana, a small isolated near-shore mountain; fewer than 40 plants exist. Jaltomata umbellata and J. aspera appear not to be in imminent danger of extinction, but the populations growing on the edge of the city of Lima have been eliminated by the expansion of the city. Jaltomata aspera and Jaltomata quipuscoae are the only members 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 seven 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? Two non-mutually exclusive possibilities come to mind:

1) Separate dispersal events from (or to?) the Andes, with populations originally small and therefore subject to genetic drift, 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 that grow exclusively in the lomas 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. J. 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.

Red-Orange Nectar: Jaltomata aspera, J. umbellata and J. quipuscoae produce red-orange nectar. Follow this link for a table of Jaltomata species having red to orange nectar.

Endemism: Five of the seven species are endemic to the lomas; see table for details.

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

Keys to the Jaltomata of the Peruvian lomas formations:

Key A.

1. Floral nectar red/orange . . . . . . . . . . . . . . . . . . . . . . . . 2

1. Floral nectar transparent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2. Corolla tubular, shrub . . . . . . . . . . . . . . . . . . . . . . . J. umbellata

2. Corolla very broadly campanulate, herbaceous or woody only at base . . . . 3

3. Lacking 10 green corolla spots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . J. aspera

3. Having 10 green corolla spots . . . . . . . . . . . . . . . . . . . . . . . . . . . J. quipuscoae

4. Branches villous with gland-tipped hairs. . . . . . . . . . . J. hunzikeri

4. Branches essentially glabrous . . . . . 5

5. Filaments essentially glabrous . . . . J. atiquipa

5. Filaments villous along lower approximately half . . . . . . 6

the following couplet no longer works, given photos of J. lomana provided by S. L. G.

6. Stamens included (inside of corolla); corolla 5-lobed . . . . . . J. lomana

6. Stamens exserted; corolla 10-lobed . . . . . . . . . . . . . . . . . . . J. truxillana

Key B.

1. Herbaceous but possibly woody at ground-level; corolla crateriform (very broadly campanulate); nectar red . . 2

1. Shrubs; corolla short-tubular or crateriform; nectar clear or red . . . . . . . . . . . . . . . 3

2. 10 green corolla spots, the corolla purple . . . . . . . . . . . . . . . . . . J. quipuscoae

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

3. Corolla tubular, the tube at least 6.5 mm long; nectar red . . . . . . . . . . . . . . . J. umbellata

3. Corolla crateriform or tubular, the base 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. Slender part of filament (not the base) glabrous . . . . J. atiquipa

5. Slender part of filament (not the base) villous along approximately lower half . . . . . . . . . . . . . . . . 6

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

6. Corolla 10-lobed, the limb lavender near tube, fading to white toward margin of limb, the limb planar; stamens exserted . . . . . J. truxillana