Terraria haydenii T.Hildebrand & Al-Shehbaz, 2017

Hildebrand, Terri J. & Al-Shehbaz, Ihsan A., 2017, Terraria haydenii (Thelypodieae, Brassicaceae), a new mustard genus and species from the West Desert region of North America’s Great Basin, Phytotaxa 323 (2), pp. 128-142 : 137-140

Terraria haydenii T.Hildebrand & Al-Shehbaz , sp. nov. ( Figures 5 & 6 )

TYPE: U.S.A. Utah, Beaver County, Wah Wah Mountains , 36 km NW of Milford on Hwy 21 to top of pass then 0.5 km N, 38°31.393′N, 113°33.459′W, UTM 4266971 N 277033 E Z12 S, 13 June 2012, 1982 m, Terri J. Hildebrand 4202 (holotype MO-6722745; isotype MSUNH) .

Herbs cespitose perennials, glaucous, sparsely puberulent with simple trichomes 0.04‒0.12 mm; caudex several to many branched, covered with persistent petiolar bases of previous seasons. Stems erect, 0.5‒2.5 cm, glaucous. Basal leaves oblanceolate to lanceolate, 4‒10 × 1‒2 mm, fleshy with a glaucous covering, becoming leathery when dry, sparsely puberulent, apex acute, margin entire or rarely with 1 or 2 subapical teeth, base attenuate to a petiole 0.5‒2 mm long; cauline leaves 2‒6, similar to basal leaves, entire. Racemes 4‒10-flowered, not or slightly elongated in fruit; fruiting pedicels 3‒4(‒5) mm long, straight, ascending to divaricate, glabrous or minutely puberulent. Sepals narrowly oblong, 3‒4 × ca. 1 mm, glabrous; petals white, oblong, 4‒6 × 1.2‒1.5 mm; claw 2‒2.5 mm long, about as wide as blade; filaments white, 1.5‒2 mm long, dilated at base; anthers oblong, 1.2‒1.5 mm long. Fruits narrowly oblong to lanceolate, (3‒)4‒7 × 1.2‒1.5 mm; valves glabrous, with a prominent midvein extending full length; gynophore 0.1‒0.6 mm long; style slender, 0.5‒0.8(‒1.2) mm long. Seeds yellow-brown, ovoid to narrowly so, 1.1‒1.5 × 0.7‒0.8 mm.

Paratype: U.S.A. Utah, Beaver County, Wah Wah Mountains, Spider Marble Mound, 36 km NW of Milford on Hwy 21 to top of pass then 0.2 km S, 38°30.805′N, 113°32.568′W, UTM 4265846 N 278297 E Z 12 S, 1971 m, 28 April 2013, Terri J. Hildebrand 4260 ( MSUNH).

Etymology: —The genus name Terraria is derived from the Latin “terra”, meaning “from the earth” in relation to the plant’s diminutive size. In addition, “aria” is a suffix meaning “air”, an appropriate descriptive of the vast, open spaces of the Great Basin West Desert region. The specific epithet haydenii is named in honor of T. Hildebrand’s grandson, Hayden, botanist in the making.

Relationships: —Although the placement of Terraria in the Thelypodieae and the expanded Lineage II are firmly established herein, perhaps the closest North American relatives of this genus are the Utah-endemic members of Hesperidanthus (B.L. Robinson 1895: 174) Rydberg (1907: 433) as delimited by Al-Shehbaz (2005). From this genus, Terraria differs by having rosulate (vs. no) basal leaves, simple trichomes (vs. none), racemes hardly (vs. distinctly) elongated in fruit, spreading (vs. erect to ascending) sepals, oblong (vs. obovate to spatulate) and white (vs. yellow, purple, lavender, or rarely white) petals, lateral (vs. confluent) nectar glands, ovules 4‒8 (vs. 8‒110) per ovary, narrowly oblong to lanceolate (vs. linear) fruit, and slightly 2-lobed stigmas with lobes opposite valves (vs. entire and capitate or strongly 2-lobed with decurrent lobes opposite repulm).

Terraria haydenii superficially resembles and may be confused with the two species of Cusickiella Rollins (1988: 68) , tribe Boechereae of Lineage I, in habit and general aspects of flowers, seeds, fruits, and cotyledonary type. However, it differs by not being pulvinate and by having exclusively simple, minute trichomes, spreading sepals, oblong anthers, only lateral nectar glands, 4‒8 ovules per ovary, narrowly oblong to lanceolate siliques, and slightly 2-lobed stigmas. By contrast, Cusickiella plants are pulvinate with simple and branched trichomes, erect sepals, ovate anthers, median nectar glands, 4 ovules per ovary, ovoid to ellipsoid silicles, and entire stigmas.

Distribution, habitat, and ecology:— Currently, the known distribution of Terraria haydenii is represented by two populations in the Wah Wah Mountains of the Great Basin West Desert, one located at the Original Discovery site and another, larger population growing on top of Spider Marble Mound. Plants are limited to very alkaline soils associated with Upper Cambrian-Ordovician limestone, with white, locally conglomeratic quartzite. They grow under an open canopy in a very dry habitat inhabited by few other plant species. Evidence of herbivory was noticed on the leaves, and very small Coleoptera were observed on the plants ( Figure 7 ). With its thick, fleshy leaves, it is possible T. haydenii plants play an important ecological role in this harsh microenvironment characterized by temperature extremes and low moisture levels. The pollination system of Terraria haydenii is currently unknown.

Conservation status:— Terraria haydenii populations occur in an area peppered with mineral exploration. Despite location on federal lands (BLM), adjacent mineral claim activity on the Original Discovery site, as well as disturbance by rock collectors gathering lined marble on the Spider Marble Mound site, have the potential to negatively impact the populations. Some disturbance may contribute to the success of Terraria haydenii populations by removing competitors, but without well-structured, long-term monitoring, no conclusive statement can be made. Additionally, extensive mineral extraction, such as that experienced in the Frisco area would severly impact all plant populations. Further surveys for Terraria haydenii locations in the mountain ranges of the western Great Basin may greatly increase understanding of the plant’s distribution and conservation status.

IUCN Red List Category:— Terraria haydenii is known only from the two collections above. A full conservation assessment cannot be determined at this point and, therefore, according to the IUCN (2001) classification, we prefer to give it a Data Deficient (DD) criterion.

Figures

FIGURE 5. Terraria haydenii.A. Plant; B. Basal leaf; C. Sepal; D. Petal; E. Fruit and fruiting pedicel. Scales:A = 1 cm; B, D = 1 mm; C, E = 2 mm. Drawn by Al-Shehbaz from the holotype Hildebrand 4202 (MO).

FIGURE 6. Image of Terraria haydenii in full flower. Photo by T. Hildebrand in 2013.

FIGURE 7. Evidence of herbivory was readily apparent on plants, particularly during the 2012 season that occurred after winter and summer drought conditions (A). In the 2013 season, beetles (Coleoptera) were discovered feeding on the plants (B). Images by T. Hildebrand.