Lamourouxia pacifica Franc.Gut. & Ruiz-Sanchez, 2022

Francisco-Gutiérrez, Antonio, Ruiz-Sanchez, Eduardo, González, Dolores & Lira-Noriega, Andrés, 2022, Two new species of Lamourouxia section Hemispadon (Orobanchaceae) from western Mexico, Phytotaxa 549 (1), pp. 51-66 : 58-62

Lamourouxia pacifica Franc.Gut. & Ruiz-Sanchez sp. nov. ( Figs. 5 , 6 A, C, E, G ).

Lamourouxia pacifica belongs to the section Hemispadon and it can be distinguished from the other species by having leaves linear to linear-lanceolate with brochidodromous venation and presence of lower bracts linear to lanceolate, both leaves and bracts are membranous.

Type: — MEXICO. Jalisco: Cabo Corrientes, km 176 on road from Puerto Vallarta to Manzanillo , 20.380114, -105.311936, 701 m, 23 February 2019, Antonio Francisco-Gutiérrez & Rebeca Rosas-Campos 251 (holotype XAL!) .

Herbs up to 2 m, stems erect, solitary or branched near the base, pubescent to scarcely hirsute with glandular hairs. Leaves opposite, sessile, linear to narrowly linear-lanceolate, 38–138.2 × 8–25 mm, apex acute, base cuneate or rounded, margin serrate with up to 37 teeth each side, teeth 0.5–0.9 mm long each, adaxially pubescent to scarcely hirsute with a mix of simple and glandular trichomes, abaxially pubescent with simple and glandular trichomes, venation brochidodromous with the primary and secondary veins conspicuous. Lamina chartaceous, light green. Inflorescence a raceme, 9.5–34 cm long, ascending, pubescent with glandular trichomes; pedicellate flowers, pedicels 1–9 mm long, pubescent with glandular trichomes; one bract per flower, bracteoles absent. Bracts divided in two types, upper bracts triangular to lanceolate, 5–23 × 2–10.4 mm, apex acute, base rounded, margin entire, adaxial and abaxially pubescent with simple and glandular trichomes; lower bracts linear to lanceolate, 17–37 × 6–8 mm, apex acute, margin serrate with up to 11 teeth each side, each tooth up to 1 mm long. Calyx campanulate, 3.2–10 × 3–7 mm, four-lobed, each lobe 2–7 × 1.5–4 mm, triangular, erect, apex acute, margin entire, one midvein per lobe, pubescent with glandular trichomes. Corolla tubular 15–46 × 3–6.2 mm, bilobed, the upper lip 7–23 × 5–10 mm, rectangular, apex acute to obtuse, margin entire or occasionally with one rounded tooth of 1 mm long at each side, reflexed or not, externally sericeous to lanose with pink-colored trichomes; lower lip 7–17 × 3–5.1 mm, linear, margin entire, three-lobed, each lobe ca. 3.5 × 1.5–1.9 mm, revolute. Corolla very fragile and deciduous. Filaments 36–43 mm long, anthers 3–3.5 mm long, shaggy with white non-glandular trichomes. Style 33–44 mm long, scarcely pubescent, persistent in fruiting, white to black throughout fruiting. Stigma capitate, 0.9–1.2 × 1 mm. Fruit a capsule, elliptic to ovoid, 8.2–12 × 4–8 mm, glabrous, with longitudinal dehiscence, light green when immature and dark brown when mature. Seeds numerous, 1.2–1.3 × 0.5–0.7 mm, with white reticulated coat.

Distribution and Ecology — Lamourouxia pacifica is distributed in the northern and western states of Durango, Jalisco, Nayarit, and Sinaloa, Mexico ( Fig. 4 ). This species occurs from 300 to 1400 m a.s.l. in oak and pine-oak forests. Reported genera around the new species are Dioon Lindley (1843: 59–60) and Zamia Linnaeus (1763: 1659) (Zamiaceae) .

Phenology: —Specimens with flowers were recorded from November to May. Collections with fruits were registered from February to April.

Etymology: —The specific epithet refers to the distribution of the species close to the Pacific Ocean.

Conservation status:— Lamourouxia pacifica with 10 records has an extent of occurrence (EOO) of 88,839.25 km 2, and area of occupancy (AOO) of 36 km 2. Botanical expeditions in 2020 and 2021 near the type locality allowed to observe a reduction in the extent and quality of habitat caused by deforestation and forest fires. The species is listed as Endangered species EN B2 b(ii,iii). Only one specimen of the species was collected near the Sierra de Quila Flora and Fauna Protection Area, and the rest of specimens are distributed in areas with no protection ( Fig. 4 ) .

Discussion:— Lamourouxia viscosa is the most widely distributed and collected species of the genus, from northern Mexico to Panama. During the revision of main herbaria from Mexico, hundreds of specimens of the genus determined as L. viscosa were found, including specimens of the section Lamourouxia , which the species does not belong. This is due to the morphological variation that occurs in the species. The description of L. viscosa published in the treatment of the genus includes a brief description of a similar taxon “probably closest to L. viscosa ” ( Ernst 1972: 49) , which possesses membranous and narrow leaves with widely spaced teeth. This taxon was not formally named neither validly published. The next paragraph contains the morphological description of L. viscosa , where the leaves were described to be broadly or narrowly ovate to elliptical or lanceolate. Here, we proposed L. pacifica as a different species by its distinguishable shape of the leaves, which are linear to linear-lanceolate. The leaves also have a greater number of spaced teeth, up to 37 on each side, while L. viscosa has up to 27 teeth per side. The pattern of venation in the abaxial surface of the leaves of L. viscosa is reticulate with very conspicuous primary, secondary, and tertiary veins (distinguished from the rest of the genus as “prominent reticulate tertiary veins”) ( Ernst 1972). On the other hand, the pattern in L. pacifica is brochidodromous, with primary and secondary veins conspicuous. Other character that can help to identify L. pacifica is the presence of linear to linear-lanceolate bracts at the base of the inflorescence (lower bracts). In contrast, L. viscosa generally shows bracts ovate, which have the same shape along the inflorescence. Another feature that can be perceived in field is the texture of the leaves. Typically, the leaves of L. viscosa are strongly coriaceous and sometimes contact with teeth can hurt. Contrarily, leaves of L. pacifica are membranous and soft to the touch. All these differences allow to establish L. pacifica as a separate species. A detailed morphological comparison with respect to widespread L. viscosa is shown in the Table 3 and Fig. 6 .

(1972).

Additional specimens examined (Paratypes):— MEXICO. Sinaloa: Mesa Malqueson, Cerro Colorado, 2500 ft, 08 December 1939, Gentry 5168 ( MEXU!) . Durango: Tamazula, La Bajada, 1750 m, November 1922, González-Ortega 563 ( MEXU!) . Nayarit: Tepic, 1 km al SW de El Cuarenteño camino a El Cora o 4 km al N del entronque del camino El Cora-Papapitas, 820 m, 16 May 1994, Flores-Franco et al. 3458 ( MEXU!) ; W-SW flank of Volcan Sanganguey, track from highway to Guadalajara ca. 6 km SE of San Cayetano, 1400 m, 13 January 1993, Mayfield et al. 1657 ( MEXU!) ; Tepic, Las Tierritas, 2 km al NE del Izote, Cerro San Juan, 1200 m, 23 March 1989, Tenorio et al. 15610 ( MEXU!) . Jalisco: Ayotitlán, al NNE de Ayotitlán, 1320 m, 26 February 1987, Alcocer et al. 242 ( IBUG!) ; Cabo Corrientes (El Tuito), alrededores de La Báscula, por el camino a El Cuale , 815 m, 24 February 1993, Castillo-Campos et al. 10281 ( XAL!) . Cabo Corrientes, La Puerta, 500 m, 27 February 1993, Castillo-Campos et al. 10489 ( XAL!) ; Tecalitlán, Sierra del Halo, predio Las Palomas y Los Fresnos , 12 km en línea recta al E de Pihuamo , 3.5 km al O de Alotitlán, alrededores del Puerto de Ortiz , 1750 m, 22 April 2012, Castro-Castro et al. 2789 ( XAL!) ; Cabo Corrientes, Carretera Puerto Vallarta - El Tuito km 178, 700 m, 06 March 2021, García et al. 338, Ortiz-Brunel et al. 1058 ( IBUG!) ; Cabo Corrientes, camino El Tuito – minas de Zimapán , 820 m, 06 March 2021, Ortiz-Brunel et al. 1059 ( IBUG!) .

Key for the species of the section Hemispadon (Modified from Ernst 1972).

1. Calyx and leaves pubescent................................................................................................................................................................2

- Calyx and leaves glabrous or glabrate................................................................................................................................................3

2. Leaves sessile .....................................................................................................................................................................................4

- Leaves petiolate..................................................................................................................................................................................5

3. Leaves ovate, elliptical to obovate .....................................................................................................................................................6

- Leaves lanceolate to subulate .............................................................................................................................................................7

4. Calyx with glandular trichomes..........................................................................................................................................................8

- Calyx with non-glandular trichomes ..................................................................................................................................................9

5. Leaves lanceolate, 50 mm or more long; calyx lobes 10–12 mm long, glandular............................................................ L. jaliscana

- Leaves ovate, up to 25 mm long; calyx lobes 2–5 mm long, not glandular.................................................................... L. gutierrezii

6. Leaves 18–28 mm long ....................................................................................................................................................................10

- Leaves less than 10 mm long........................................................................................................................................ L. microphylla

7. Inflorescence tips ascending; calyx lobes 6 mm or less long; branching ascending........................................................................11

- Inflorescence tips patent; calyx lobes 6–15 mm long; branching at nearly right angles................................................. L. lanceolata

8. Leaves narrowly or broadly ovate to lanceolate, truncate or cordate at base; same shape of bracts along the inflorescence .........12

- Leaves linear to narrowly linear-lanceolate, cuneate or rounded at base; two shapes of bracts at inflorescence ............... L. pacifica

9. Calyx lobes entire.............................................................................................................................................................................13

- Calyx lobes frequently irregular to dentate ............................................................................................................... L. rhinanthifolia

10. Leaves elliptical to obovate; calyx lobes up to 2 mm long, corolla 45–49 mm long, 8–10 mm wide................................ L. gracilis

- Leaves ovate, calyx lobes 4–6 mm long, corolla up to 35 mm long, up to 7 mm wide...................................................... L. colimae

11. Leaf blades subulate, irregularly dentate, up to 3 mm wide............................................................................................. L. tenuifolia

- Leaf blades lanceolate, sub-entire, 3–7 mm wide ......................................................................................................... L. integerrima

12. Leaves up to 15 mm wide, not scabrous, margins up to 14 dentate on a side, not reticulate below, calyx lobes 4–27 mm long........ ............................................................................................................................................................................................. L. nelsonii

- Leaves 15 mm or more wide, often scabrous, margin 14 or more dentate on a side, reticulate venation standing out below, calyx lobes 2–4 mm long ............................................................................................................................................................... L. viscosa

13. Leaves elliptic to oblong, up to 29 mm wide, rounded at base; lobes of the lower lip patent ........................................ L. avendanoi

- Leaves ovate, 29–38 mm wide, conspicuously cordate at base; lobes of the lower lip revolute .......................................... L. smithii

Figures

FIGURE 4. Distribution map of the new endemic species of Lamourouxia distributed in western Mexico and location of natural protected areas in the country.

FIGURE 5. Holotype of Lamourouxia pacifica (Francisco-Gutiérrez & Rosas-Campos 251, XAL). Photograph: Sergio Avendaño- Reyes.

FIGURE 6. Visual comparison of morphological structures of Lamourouxia pacifica in relation to L. viscosa. Photographs: Antonio Francisco-Gutiérrez (C, D, E), Emmanuel Guevara-Lozano (F), Eduardo Ruiz-Sanchez (A, G), Ignacio Torres-García (B), Monitoreo Comunitario El Toro (H).