Mats Thulin® ^(1){ }^{1}, Michael Weber ^(2){ }^{2}, Sami Ali Mohammed Mubarak ^(3){ }^{3} and Alain Rzepecky® ^(4){ }^{4} 马茨·图林® ^(1){ }^{1} 、 迈克尔·韦伯 ^(2){ }^{2} 、 萨米·阿里·穆罕默德·穆巴拉克 ^(3){ }^{3} 和 阿兰·热佩茨基® ^(4){ }^{4}^(1){ }^{1} Department of Organismal Biology, Systematic Biology, EBC, Uppsala University, Uppsala, Sweden ^(1){ }^{1} 乌普萨拉大学 EBC 生物生物学系，系统生物学，瑞典乌普萨拉^(2){ }^{2} Dorfstrasse, Bad Berka, OT Tiefengruben, Germany ^(2){ }^{2} Dorfstrasse， Bad Berka， OT Tiefengruben， 德国^(3){ }^{3} Socotra Island, Yemen ^(3){ }^{3} 也门 索科特拉岛^(4){ }^{4} Sitio da Mesquita Alta, São Brás de Alportel, Portugal ^(4){ }^{4} Sitio da Mesquita Alta， São Brás de Alportel， 葡萄牙Correspondence: Mats Thulin (mats.thulin@ebc.uu.se) 通信地址：Mats Thulin （mats.thulin@ebc.uu.se）
The new species Boswellia hesperia Thulin, M.H.Weber and Rzepecky is described, illustrated and mapped. It is a dwarf tree, restricted to westernmost Socotra (Yemen), growing on limestone rocks, in which the usually prostrate stems tend to fill out holes and crevices. It differs from B. nana Hepper, another dwarf tree endemic to Socotra but restricted to the easternmost parts of the island, by having leaves densely pubescent with whitish hairs beneath and by its smaller flowers and fruits. 对新物种 Boswellia hesperia Thulin、M.H.Weber 和 Rzepecky 进行了描述、插图和绘图。它是一种矮小的乔木，仅限于最西端的索科特拉岛（也门），生长在石灰岩上，其中通常匍匐的茎往往会填满孔洞和裂缝。它与 B. nana Hepper 不同，B. nana Hepper 是索科特拉岛特有的另一种矮树，但仅限于该岛的最东端，其叶子有密集的短柔毛，下面有白色的毛，花朵和果实较小。
The dwarf frankincense tree Boswellia hesperia was provisionally described by Thulin (2020) based on photographs from two localities in western Socotra (Yemen). The species was first mentioned and depicted as a dwarf form of B. popoviana Hepper by Miller and Morris (2004). At that time apparently only sterile plants had been seen and photographed at Heger above Bandar Shu’ub, and the similarity in habit with the dwarf tree BB. nana Hepper was pointed out. A second population from above Neet was found by Lisa Banfield and Tony Miller in October 2007 and included both flowering and fruiting plants (Fig. 1), but again no material that could be used for typification was collected. 矮小乳香树 Boswellia hesperia 由 Thulin （2020） 根据索科特拉岛西部（也门）两个地方的照片临时描述。该物种首次被 Miller 和 Morris （2004） 提及并描述为 B. popoviana Hepper 的矮小形式。当时，显然在 Bandar Shu'ub 上方的 Heger 只看到和拍摄了不育植物，以及与矮树 BB 的习性相似。娜娜·赫珀 （nana Hepper） 被指出来。Lisa Banfield 和 Tony Miller 于 2007 年 10 月发现了 Neet 上方的第二个种群，包括开花和结果植物（图 1），但同样没有收集到可用于类型化的材料。
During visits to western Socotra in July 2012 and May 2021, AR found the species in two further localities, sterile in the 2012 locality, but with flowers and fruits in 2021 (Fig. 2). Pyrenes were collected in 2021, from which seedlings were grown in Portugal. In April 2023, MW and SAMM visited an area close to the 2007 locality and, apart from documenting the finding by photographs (Fig. 3), also made a small collection of flowering shoots of the species. During a visit in May 2024, several further populations of the species were detected (Fig. 4) in some new localities, and another small collection was made, including some fruits. All this now makes formal publication of B. hesperia possible. For conservation reasons, the coordinates for the localities have been omitted. 在 2012 年 7 月和 2021 年 5 月访问索科特拉岛西部期间，AR 在另外两个地方发现了该物种，在 2012 年地点不育，但在 2021 年有花和果实（图 2）。比利牛斯山脉于 2021 年收集，并在葡萄牙种植幼苗。2023 年 4 月，MW 和 SAMM 访问了 2007 年地点附近的一个地区，除了用照片记录这一发现（图 3）外，还收集了该物种的少量开花芽。在 2024 年 5 月的一次访问中，在一些新的地方检测到了该物种的几个其他种群（图 4），并进行了另一个小规模收集，包括一些水果。所有这些都使 B. hesperia 的正式出版成为可能。出于保护原因，省略了地点的坐标。
Figure 1. Boswellia hesperia sp. nov., plant filling out hole in limestone rock, showing leaves and reddish flowers; above Neet, Socotra, 31 Oct. 2007. Photograph by Lisa Banfield. 图 1.Boswellia hesperia sp. nov.，植物在石灰岩中填洞，露出叶子和淡红色的花朵;Above Neet，索科特拉岛，2007 年 10 月 31 日。照片由 Lisa Banfield 拍摄。
A dwarf tree similar to Boswellia nana Hepper, but differing by having leaves densely pubescent with +-\pm crisped whitish hairs (versus glabrous or subglabrous) beneath, smaller flowers with petals 3-4mm3-4 \mathrm{~mm} (versus 4.5-5.5mm4.5-5.5 \mathrm{~mm} ) long and smaller fruits ( 5-7mm5-7 \mathrm{~mm} versus ca 10 mm long). 一种类似于 Boswellia nana Hepper 的矮小乔木，但不同之处在于叶子密密被短柔毛，下面有 +-\pm 脆脆的白色毛（与无毛或无毛相比），花较小，花瓣 3-4mm3-4 \mathrm{~mm} （相比 4.5-5.5mm4.5-5.5 \mathrm{~mm} ）长，果实较小（ 5-7mm5-7 \mathrm{~mm} 与约 10 毫米长相比）。
Dwarf tree, +-\pm prostrate; bark greyish or whitish, smooth, not flaking; young shoots pubescent with white to brownish +-\pm crisped hairs. Leaves densely crowded at shoot apices or alternate on young long-shoots, simple; blade 7-18 xx3-11mm7-18 \times 3-11 \mathrm{~mm}, oblong-elliptic, broadly cuneate to truncate or cordate at the base, obtuse at the apex, strongly and irregularly crenateundulate and often brownish at the margins or sometimes pinnately lobed, dark green and sparsely pubescent with crisped hairs on the nerves above, densely pubescent with +-\pm crisped whitish hairs and prominently veined beneath, becoming vermilion before shedding; petiole 1-8(-12)mm1-8(-12) \mathrm{mm} long, pubescent with crisped hairs. Flowers produced with the leaves or sometimes in leafless plants, solitary, pedicels 矮树， +-\pm 匍匐;树皮灰白色或白色，光滑，不剥落;嫩芽有短柔毛，有白色至褐色 +-\pm 的脆毛。叶子在嫩芽顶端密集拥挤，或与年轻的长芽交替，简单;叶片 7-18 xx3-11mm7-18 \times 3-11 \mathrm{~mm} ，长圆形，基部宽楔形至截断或花纹，顶端钝，强烈且不规则的锯齿状起伏，边缘常呈褐色，有时羽状裂片，深绿色，稀疏被短柔毛，上面有脆脆的毛，密集的短柔毛， +-\pm 有脆白的毛，下面有明显的脉络，在脱落前变成朱红色;叶柄 1-8(-12)mm1-8(-12) \mathrm{mm} 长，有短柔毛，有脆皮的毛。花与叶子一起产生，有时在无叶植物中产生，单生，花梗 4-20mm4-20 \mathrm{~mm} long, reddish or brownish, glabrous or almost so; bracteoles lanceolate, 0.4-0.6mm0.4-0.6 \mathrm{~mm} long, pubescent. Calyx cup-shaped, 1 mm long, with 5 broadly triangular lobes, glabrous or tips of lobes minutely pubescent. Petals (3-)5, reddish, reddish white, cream or whitish, often with +-\pm reddish tips, with a reddish hue or with reddish midvein, 3.0-3.0-4.0 xx1.2-2.4mm4.0 \times 1.2-2.4 \mathrm{~mm}, spreading in open flowers, +-\pm narrowly ovate-oblong, glabrous outside, minutely papillose on the inner surface and along margins. Stamens (6-) 10, subequal, inserted at the base of the disk; filaments 2.0-2.5mm2.0-2.5 \mathrm{~mm} long, narrowly triangular, glabrous, reddish; anthers 1 mm long, oblong, glabrous, cream. Disk cup-shaped, 1.5-2.2mm1.5-2.2 \mathrm{~mm} in diam., glandular, orange or reddish. Pistil 2.0-2.5mm2.0-2.5 \mathrm{~mm} long, with reddish subglobose ovary, glabrous, with 3-4 furrows; style 1.0-1.5mm1.0-1.5 \mathrm{~mm} long; stigma truncate-capitate, green. Fruits 3-43-4-locular, 5-7xx3-5mm5-7 \times 3-5 \mathrm{~mm}, +-\pm broadly pyriform to obovoid or subglobose, glabrous, purplish brown; pyrenes 4.0-5.0 xx2.0-3.5mm4.0-5.0 \times 2.0-3.5 \mathrm{~mm}, narrowing at both ends, trigonous, not or scarcely winged. 4-20mm4-20 \mathrm{~mm} 长，微红或褐色，无毛或几乎如此;苞片披针形， 0.4-0.6mm0.4-0.6 \mathrm{~mm} 长，有短柔毛。花萼杯状，长 1 毫米，有 5 个宽三角形的裂片，无毛或裂片顶端有细短柔毛。花瓣（3-）5，微红，红白色，奶油色或白色，通常有 +-\pm 红色的尖端，带有淡红色的色调或带有淡红色的中脉， 3.0-3.0-4.0 xx1.2-2.4mm4.0 \times 1.2-2.4 \mathrm{~mm} 在开放的花朵中展开， +-\pm 窄卵形长圆形，外面无毛，内表面和沿边缘有微小的状体。雄蕊 （6-） 10，次相等，插入盘基部;花丝 2.0-2.5mm2.0-2.5 \mathrm{~mm} 长，窄三角形，无毛，淡红色;花药长 1 毫米，长圆形，无毛，奶油色。盘状杯形， 1.5-2.2mm1.5-2.2 \mathrm{~mm} 直径，腺体，橙色或淡红色。雌蕊 2.0-2.5mm2.0-2.5 \mathrm{~mm} 长，有淡红色的近球形子房，无毛，有 3-4 条沟;风格 1.0-1.5mm1.0-1.5 \mathrm{~mm} 长;柱头截头状，绿色。果实 3-43-4 - 小房， 5-7xx3-5mm5-7 \times 3-5 \mathrm{~mm}+-\pm 宽梨状至倒卵形或近球形，无毛，紫棕色; 4.0-5.0 xx2.0-3.5mm4.0-5.0 \times 2.0-3.5 \mathrm{~mm} 芸苇，两端变窄，三角形，无翅或几乎没有翅。
Distribution and habitat 分布和栖息地
Boswellia hesperia is known only from an area close to the westernmost tip of Socotra (Fig. 8), at about 320-500m320-500 \mathrm{~m} a.s.l. It grows on limestone rocks, in which the usually prostrate stems tend to fill out holes and crevices (Fig. 1, 2A, 3C). In the 2021 locality, the number of plants was estimated to be about 300 , and in the populations seen above Neet in 2024, 乳香 （Boswellia hesperia） 仅在靠近索科特拉岛最西端的地区（图 8）已知，大约在 320-500m320-500 \mathrm{~m} a.s.l.它生长在石灰岩上，其中通常匍匐的茎往往会填满孔和裂缝（图 1、2A、3C）。在 2021 年的地方，植物的数量估计约为 300 株 ，而在 2024 年 Neet 上面看到的种群中，
Figure 2. Boswellia hesperia sp. nov. from mountain ridge above Neet, 5-6km5-6 \mathrm{~km} from the coast, Socotra, 18 May 2021. (A) plant filling out crevice in limestone rock, leafless, showing reddish white flowers and fruits, (B) leafless plant with flowers and fruits. Photographs by Alain Rzepecky. 图 2.Boswellia hesperia sp. nov.2021 年 5 月 18 日，从海岸出发，从索科特拉岛的尼特 5-6km5-6 \mathrm{~km} 山脊上。（A） 植物填充石灰岩的缝隙，无叶，开出红白色的花和果实，（B） 无叶植物，有花和果实。摄影：Alain Rzepecky。
the estimated number of plants was 1000 or more. Thulin (2020) previously estimated the number of plants to be less than 50 , but after an extensive search since then, 334 plants were counted and the total population size was estimated to 1000 by Madĕra et al. (2024). However, also this figure is surely too low; the total number is at least 1500 . 估计植物数量为 1000 株或更多。Thulin （2020） 之前估计植物的数量少于 50 株，但此后经过广泛搜索，Madĕra 等人（2024 年）统计了 334 株植物，总种群规模估计为 1000 株。然而，这个数字肯定也太低了;总数至少为 1500 。
Etymology 词源
The epithet ‘hesperia’ (Latin, western) refers to the distribution of this species that is restricted to the westernmost part of Socotra. 绰号“hesperia”（拉丁语，西部）是指该物种的分布仅限于索科特拉岛的最西端。
Notes on taxonomy 分类法说明
The dwarf habit, solitary flowers and fruits of BB. hesperia agree quite well with BB. nana, which is likely to be the nearest 矮小的习性，独居的花和果实。 BB Hesperia 非常 BB 同意 。nana，这可能是最近的
relative, but it differs most markedly in the dense and whitish indumentum of the lower surfaces of the leaves (Fig. 3B). In B. nana, the lower surfaces of the leaves are glabrous or subglabrous. Also the leaf margins (Fig. 1, 3, 4) are more strongly crenate-undulate in BB. hesperia than in BB. nana. Furthermore, the plants of BB. hesperia seen so far are always more or less prostrate dwarf trees, whereas in BB. nana plants may grow up to about 2 m tall. 相对的，但它最明显的区别在于叶子下表面的致密和白色的被层（图 3B）。在 B. nana 中，叶子的下表面是无毛的或近无毛的。此外，叶缘（图 1、3、4）在 BB 中更强烈地锯齿状起伏。hesperia 比 . BB 娜娜。此外，植物 BB .到目前为止看到的 Hesperia 总是或多或少匍匐的矮树，而在 BB .Nana 植物可以长到约 2 m 高。
The indumentum of the leaves in BB. hesperia agrees better with that in BB. popoviana, with which it was associated by Miller and Morris (2004) However, B. hesperia differs from B. popoviana in the dwarf habit and in the inflorescences with solitary flowers only (versus flowers in panicles). Also, the strongly crenate-undulate leaf margins differ from anything seen in B. popoviana. 叶子的被毛。 BB Hesperia 更同意 中的 BB 这一点。popoviana，Miller 和 Morris （2004） 与之相关。然而，B. hesperia 与 B. popoviana 的不同之处在于矮小的习性和仅具有单花的花序（与圆锥花序中的花相比）。此外，强烈锯齿状起伏的叶缘与 B. popoviana 中看到的任何叶缘都不同。
