Trichostema latens K. S. McClell., 2023

Mcclelland, R. Kevan Schoonover, Weakley, Alan S. & Poindexter, Derick B., 2023, Seven new species of Trichostema (Lamiaceae: Ajugoideae) from the North American Coastal Plain biodiversity hotspot, Phytotaxa 603 (2), pp. 95-149 : 112-113

Trichostema latens K. S. McClell. , sp. nov. ( Figure 12 )

Diagnosis: —Herbaceous to woody annual to 50 cm tall, morphologically most similar to Trichostema dichotomum . It differs from T. dichotomum by its oblong to oblanceolate leaves (vs. lanceolate to elliptic), obtuse to emarginate leaf apices (vs. acute to obtuse), shorter fruiting calyces of 5.44–5.89 mm (vs. 5.91–7.24 mm), style branch ratio of 1:2–1:4 (vs. 1:1–1:2), and shorter mature nutlets of 1.61–1.77 mm (vs. 1.75–2.16 mm) with small alveoli (vs. mid-sized to large alveoli; Figure 2 ).

Type: — U.S.A. Florida. Franklin County. F . S . U. [Florida State University] Coastal Marine Lab. W side of tidal creek on N side HWY 98. 15 November 2012, Loran Anderson 26815 (holotype NCU!; isotypes FLAS!, GH!, NY!, US!, USF!) .

Herbaceous to woody annual to 50 cm tall; branching primarily in the middle to upper part of the plant; stem hairs downwardly curved, rarely spreading to two, occasionally to three, cells long, with sessile glands; node hairs downwardly curved, rarely spreading, to two, occasionally to three, cells long; leaves widest towards the tip or near the middle, rarely widest towards the base, (1.8–)1.97–3.33(–3.6) × (0.42–)0.53–0.99(–1.1), average of 2.65 × 0.76, cm, (3–)3.18–3.95(–4.52), average of 3.56, times long as wide, base cuneate to attenuate, margin entire, apex rounded to emarginate; inflorescence hairs spreading, rarely upwardly or downwardly curved, to two, occasionally to three, cells long, with sessile and spreading glands to two, rarely to three, cells long (including gland); bracts widest towards the tip, occasionally widest near the middle, (4.1–)4.36–8.02(–9.8) × 1–2.23(–3), average of 6.19 × 1.61, mm, (3.27–)3.49–4.45(–5), average of 3.97, times long as wide, base cuneate to attenuate, margin entire, apex obtuse, occasionally ±90° or rounded, rarely acute or emarginate; fruiting calyx (5.3–)5.44–5.89(–5.9), average of 5.67, mm long; buds dark blue-purple, corolla dark blue or blue-purple to blue or blue-purple; anthers dark blue or blue-purple to blue or blue-purple; style bifid, the longer arm 2–4 times as long as the shorter; mature nutlets alveolate, (1.6–)1.61–1.77(–1.8), average of 1.69, mm long, hilum (0.4–)0.45–0.57(–0.6), average of 0.51, mm long, (0.25–)0.27–0.34(–0.35), average of 0.3, times the length of the nutlet alveoli small, ridges short to mid-sized ( Figure 2g ).

Phenology: —Flowers and fruits September to November.

Etymology: —The epithet latens (Latin, hidden or secret) is given to this species for two reasons. The first is for eluding the author’s notice even after several years of intense study in this genus. Two sets of specimens, one from FLAS and one from NCU (and the only ones known to the author before he collected more in October 2021), were originally identified as T. floridanum , largely based on overall morphology and locality. Upon further morphological inspection, the author noticed differences in the FLAS specimen and assumed, erroneously, that it was an aberrant form of T. floridanum . This notion was abandoned later when the author reexamined the NCU collections (the designated types), which were from a different location and year than the FLAS specimen. A subsequent collecting trip allowed the author to revisit the collection sites, where he found both previously documented populations, one of which was growing in sympatry with T. fruticosum . There were no intermediate plants seen in the sympatric population. This collecting trip allowed these populations to be included in the genetic analyses that showed these plants were indeed distinct.

The second reason for the epithet latens is that, despite extensive field work by the author, no other populations of this species were found, meaning that the only populations known are the two collection sites. There are potentially more populations hidden elsewhere in this area of Florida that are waiting to be “found,” for it is doubtful that the entirety of this species occurs in only two places on a six-mile stretch of highway.

The common name of Hidden Bluecurls is given to this species for the same reasons.

Habitat and distribution: — Trichostema latens occurs in coastal and near-coastal scrubby flatwoods; 0–5 meters; USA: Florida: Franklin County. ( Figure 13 )

Conservation status: —Only two populations of this species are known despite much searching. It seems to have a similar ecological preference to Liatris provincialis Godfrey , so it may have a similar range. Future floristic surveys in the area may turn up more populations. This species has an extremely limited range and the threat to one of the currently known populations’ existence is extremely high since it is on a roadside. Based on the data collected for this study, this species should be recognized at a G1 ranking (NatureServe 2020).

Additional specimens examined (paratypes): — U.S.A. Florida, Franklin County: NE of Carrabelle , on U.S. 98, 4.5 miles west of the bridge over Ochlochoknee Bay. On the South side of the road., 23 September 2001, Edwards & Ionta 103 ( FLAS!); Southern side of US 98, 1 road mile east of St. Teresa , 29.929721 N, 84.436264 W, 17 October 2021, McClelland & Schoonover 224 ( NCU!); Clearing north of FSU Marine lab on US 98, 29.918286 N, 84.512064 W, 17 October 2021, McClelland & Schoonover 225 ( NCU!) .

Figures

FIGURE 2. Detail of the nutlets of Trichostema section Trichostema. A) Trichostema dichotomum, B) T. setaceum, C) T. suffrutescens, D) T. nesophilum, E) T. floridanum, F) T. fruticosum, G) T. latens, H) T. bridgesii-orzellii, I) T. gracile, J) T. hobe, K) T. microphyllum. Trichostema dichotomum (A) shows large alveoli and tall ridges. T. latens (G) shows small alveoli and shorter ridges. Photos by Derick Poindexter.

FIGURE 12. Holotype specimen of Trichostema latens. Photo by R. Kevan Schoonover McClelland.

FIGURE 13. Approximate range of Trichostema latens based on field data and herbarium records. This species is only known to occur in Franklin County, Florida.