Friesodielsia brevistipitata Leerat., sp. nov.

Friesodielsia brevistipitata is most similar to F. desmoides (Craib) Steenis and F. songkhlaensis Leerat. It differs from F. desmoides in having appressed rather than erect hairs on the abaxial leaf surface, sepals 5–10 mm versus 4–5 mm long, outer petals 35–60 mm versus (19–)27–31 mm long and obtuse versus acute at the apex, and monocarp stipes 3–5 mm versus 7–10.5 mm long. From F.   songkhlaensis it may be distinguished by the shorter sepals that are rounded to an obtuse or slightly acute apex and again by the short monocarp stipes.

Etymology.— Named for the short stipes of the monocarps, among the shortest in the entire genus.

Vernacular.— Sa lao (ส่าเหล้า)(Krabi).

Friesodielsia khaoluangensis Leerat. & Aongyong, sp. nov.

Friesodielsia khaoluangensis resembles F. alpina (J.Sinclair) Steenis and F. borneensis (Miq.) Steenis in its narrow flowers and narrow leaves. From F. alpina it differs in the twigs and leaves appressed-pubescent rather than glabrous, larger leaves (13–22 × 3.8–7.5 cm versus 8.5–13 × 3–4 cm) but with only 9–12 secondary veins per side versus 12–14 per side, the pedicels ca 10 mm long versus 25–27 mm long, and the outer petals linear-lanceolate, 23–25 mm long, and appressed-pubescent versus lanceolate, ca 15 mm long, and glabrous. From F. borneensis it differs in the leaves not glaucous abaxially and with petioles 8–17 mm long instead of glaucous abaxially with petioles 4.5–8 mm long, the pedicellar bract lanceolate rather than linear, and petals 23–25 mm long rather than 52–59 mm long.

Etymology.— The species is named for the type locality.

Vernacular.— Bu nga khao luang (บุหงาเขาหลวง) (General), 

sao yut (สาวหยุด) (Nakhon Si Thammarat).

Friesodielsia  longipetala Leerat. & Chalermglin, sp. nov.

Friesodielsia longipetala is distinguished from F.  phanganensis  and F.  songkhlaensis  by its sub-coriaceous to coriaceous leaves, outer petals (50–)80–140 mm long, inner petals (11–)15–25 mm long, generally longer pedicels (up to 12 mm long), and monocarps only sparsely pubescent.

Etymology.— Named for the greater length of both the outer and inner petals compared with those of its congeners.

Vernacular.— Bu nga taeng ngan (บุหงาแต่งงาน)(General), 

sao yut (สาวหยุด)(Satun).

Friesodielsia  macrosepala Leerat. & Aongyong, sp. nov.

Friesodielsia macrosepala is similar to F. unonifolia but differs in having twigs covered by persistent mixed spreading and appressed hairs, sepals (7–)11–17 × (5–)9–11 mm, and outer petals 50–80 × 11–22 (–32) mm, with a length:width ratio ofca 4:1. Friesodielsia unonifolia, in contrast, has twigs initially covered with appressed hairs but soon glabrate, sepals 7–9 × 5.5–7 mm long, and outer petals 18–35 (–40) × 9.5–12 mm with a length:width ratio of ca 2.5:1.

Etymology.— The sepals are among the largest in the entire genus. 

Vernacular.— Bu nga sawitri (บุหงาสาวิตรี)(Nakhon Si Thammarat), 

sao yut (สาวหยุด)(Nakhon Si Thammarat)

Friesodielsia phanganensis Leerat., sp. nov.

Friesodielsia phanganensis is distinguished from F. longipetala by the chartaceous leaves, oblanceolate to elliptic-oblanceolate outer petals 50–70 mm long, inner petals 11–15 mm long, and monocarps densely pubescent with shorter stipes 3–5 mm long. 

Etymology.— The species is named for the type locality.

Vernacular.— Bu nga soeang phangan (บุหงาเซิงพะงัน)(General).

Friesodielsia songkhlaensis Leerat., sp. nov.

Friesodielsia songkhlaensis is distinguished from F. longipetala by the chartaceous leaves, pedicels 3–5 mm long with the bract exceeding the pedicel inlength, sepals tapering to a blunt-acuminate apex, outerpetals 6–12 mm wide, inner petals 8–10 mm long, and more densely pubescent monocarps.

Etymology.— Named for the Thai province in which it occurs.

Vernacular.— Bu nga soeng songkhla (บุหงาเซิงสงขลา)(General).