120
April 2015
Asklepios 120/2015
Pseudolithos P.R.O. Bally an intriguing stapeliad genus Darrel Plowes 6 Cassiobury, Murambi, Mutare, Zimbabwe. darrel.plowes@gmail.com Abstract The genus Pseudolithos P.R.O. Bally is reviewed and where available and appropriate, additional information and photographs are provided for each of the seven recognised taxa. It is demonstrated that the name Pseudolithos migiurtinus (Chiov.) P.R.O. Bally needs to be confined to plants from the limestone plateau at Eyl (Eil) in Somalia, and that the plants that occur at Galgallo and elsewhere at the Ahl Mahdu (Al Medo) mountain range south of Bosaso are not P. migiurtinus but are Pseudolithos sphaericus (P.R.O. Bally) P.R.O. Bally. Introduction Of all the described genera of stapeliads, probably no others have gripped the attention and desire of succulent enthusiasts as much as the intriguing genera Pseudolithos and White-sloanea. They are however very seldom available to would-be growers because most of these plants are very rare in the wild, and also because they grow in arid undeveloped areas that are often very insecure and highly dangerous to visit. Unfortunately the security situation there has become even worse in the past few decades, particularly in the eastern and southern half of Somalia and therefore very little more information has been available to add to what had previously been known and published about them. The first specimen of this genus to be collected was one without flowers on the limestone plateau above the Nogal River valley near Eyl (Eil) in the Majeer-
Bally (1959) Lithocaulon sphaericum Candollea 17.
teen (Migiurtinia) Sultanate region of Somalia (but which is now known as Puntland since 1998): it was collected close to the coast at Gid Gudud, a low range of hills near Eyl, by the Italian botanists Professors N. Puccioni and G. Stefanini in 1924 in what was at that time an Italian colony. However, their dried-out globose specimen remained undescribed in the Florence herbarium until 1937 when Emilio Chiovenda created the genus White-sloanea for W. crassa and incorrectly placed their specimen in it as well under the name White-sloanea migiurtina because it also had just a single stem. The next time any Pseudolithos specimens were collected in Somalia was circa 1953 when Dr Charles Koch, the founder and long-time Director of the Namib Desert Research Station, went to the GalAsklepios 120 (2015) - 3
Pseudolithos locations in Somalia. Photo courtesy of Google Earth.
gallo area south-east of Bosaso (Boosaaso) with Prof Giuseppe Scortecci of Genoa (Genova) University in the early days (1950-1960) of the United Nations mandate of the former Italian Somaliland, to investigate the tenebrionid beetles there. Koch had been asked by Bernard Carp, a close friend who had a succulent nursery at Hout Bay near Cape Town, to see what novelties he could bring back from his monthlong sojourn in that interesting area. When John Lavranos visited Carp’s nursery in 1954 he was surprised to find a number of Larryleachia–like plants planted out in a rockery in that totally unsuitable wet winter climate. The nursery manager, Rolf Rawe, told him whence Carp had obtained these plants and that Carp had steadfastly refused to give a few of them to Harry Hall, the succulent specialist at the Kirstenbosch Botanic Garden in Cape Town for safe-keeping there. However, before that Cape winter was over, all Koch’s plants were but a memory and none had survived for study and naming. In 1956, the Kenya-based Swiss botanist P.R.O. Bally collected some small unknown spherical asclepiads (Bally 10924) that resembled round pebbles at a locality that was called Baditir, which is appar4 - Asklepios 120 (2015)
ently either a small village or a hill at the southern base of the Al Madu (Ahl Mahdu/Ahl Medhow/Al Medo) mountain range south of Bosaso, for which he created a new genus Lithocaulon in which to accommodate these unusual plants and he named them Lithocaulon sphaericum. As will be discussed below under Pseudolithos migiurtinus, the similarities between these two taxa caused Bally and later authors to confuse their identities. Most of what is known about Pseudolithos plants derives from the extensive collecting trips in Somalia that were undertaken by Lavranos that commenced in 1968 and that continued on an annual basis until 1974 and thereafter intermittently until 1989: particularly relevant to this review of the genus is that he paid two visits to Galgallo (Galgala), an oasis on the southern side of the eastern end of the Ahl Mahdu Mountain about 10 km west of Karin, some 60 km SSW of Bosaso in north-eastern Somalia. Peter Bally and Frank Horwood accompanied Lavranos on some of his early expeditions to that country, and Lavranos brought flowering specimens of P. sphaericus to Bally from Eyl in January 1969, and flowering specimens of P. migiurtinus to him from Eyl in January 1970. In
Key to the species of Pseudolithos 1 - Plants with small urceolate corollas <5 mm diam. or high. Stems single or basally branched. ........................... 2 Plants with rotate or campanulate corollas >5 mm diam. Stems single with four vertical rows of tessellate flowerbearing protuberances that indicate the former location of obsolete stem corners. .................................................. 3 2 - Small flowers on stem apex; no significant external spots on corolla. Plants with 3-12 stems branching sympodially from base of initial stem..................................................................................................................... P. caput-viperae Flower umbels on basal protuberances on sides of stems at former stem angle corners; corolla tube a very small purple-spotted flattened sphere. Plants with single stems. ................................................................. P. harardheranus 3 - Former corners obsolete and rounded on old stems, corner angles not strongly sinuate. Corolla lobes with setose clavate papillae, short corolla tube present, corona purple to white, not green. ............................................ 4 Corners of old stems strongly sinuate. Corolla lobes deltoid, glabrous, spotted, no corolla tube; corona greenish. .......................................................................................................................................................................... P. horwoodii 4 - Corolla lobes linear, strongly replicate, setose with small fine crystalline clavate papillae. Corolla lobe apices lack vibratile fusiform cilia. .................................................................................................................................................... 5 Corolla lobes narrowly to broadly deltoid, margins replicate, with terete clavate purple papillae on lobes, apices with tuft of fusiform vibratile hairs...................................................................................................................................... 6 5 - Stems to 15 cm tall and 10 cm diam., spherical in juveniles. Outer corona lobes comprise smooth ridges that form pouches by connecting the bases of each inner corona lobe. ..................................................................... P. gigas Stems to 8 cm tall and 6 cm diam., quadrangular in juveniles. Bases of inner corona lobes linked by bifidlytoothed rims of outer corona pouches............................................................................................................ P. cubiformis 6 - Corolla lobes with setose papillae extending down to lobe base; corolla tube bowl-shaped, slightly deeper than wide, usually with external purple spots, throat with deeply indented pentagonal corners; corona margin spreading, rim bifidly or irregularly toothed, or broadly pointed . ....................................................... P. migiurtinus Corolla lobes with papillae only on apical halves of lobes; corolla tube wider than deep, unspotted externally, throat corners not deeply indented; corona bowl-shaped, outer lobes erect, shortly deltoid, minutely tridentate, united to bases of inner lobes as a continuous rim......................................................................................... P. sphaericus
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Pseudolithos caput-viperae Lavranos, Cact. & Succ. J. (U.S.) 46: 126-130 (1974). Flowering material of this diminutive well-camouflaged plant was collected 3 km east of Eyl (Eil) by John Lavranos on 1 January 1973 at 8°02’N, 49°58’E at 150 m on the bare wind-swept limestone plateau near the mouth of the Wadi Nogal river in north10 - Asklepios 120 (2015)
eastern Somalia. Although there are no records of it from elsewhere, it is likely to occur a short distance north and south of Eyl that have similar areas of exposed limestone. It is the only member of the genus that always has more than just a single stem - it produces 3-12 semi-upright clavate stem-like branches that grow sympodially, each starting at ground level,
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oli in January 2001 on very exposed sites on low rocky clay and limestone hills about 40 km SE of Gode on the road to Kelafo in the Ogaden region of Ethiopia, at an altitude of 300-600 m near the border with Somalia. It had previously been found in that same vicinity in 1971 by M. G. Gilbert in loose limestone scree with scattered Commiphora trees on a steep slope but his plant died before it flowered. The flowers of P. gigas are suggestive of a close relationship with P. cubiformis but Dioli (pers. com. 21.1.2015) wrote: “About P gigas it is worthy to note that it cannot be self-pollinated (contrary to P. cubiformis).” Other differences that he noted are the size of its stems (up to 15 cm high and 10 cm wide, as compared with 60-65 mm high for P. cubiformis), its spherical versus cubiform juveniles, its more smooth tuberculate epidermis, and 16 - Asklepios 120 (2015)
in the shapes of the inner corona and outer corona lobes. Furthermore, its distant location from known sites of P. cubiformis will have precluded any gene flow for a very long time, and the occurrence of a different suite of vegetation species in that well-separated ecologically different habitat also helps to indicate that it does merit having separate species rank. Pseudolithos harardheranus Dioli, Kew Bull. 57: 987 (2002). This species was also collected by Maurizio Dioli: he found it living on a very exposed almost bare limestone plateau 8 km from the sea in the Mudug Region at 180 m alt., about 12 km E of Harardhere (230 km NE of Mogadishu), Somalia, at 4°36´N, 47°57´E. The tiny purple-spotted flowers (circa 1.5 mm tall) are
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Pseudolithos sphaericus, Galgallo, NE Somalia. Fig. 1: Protuberance rows slightly spiralled, apparently 6 rows; multiple shapes and sizes of tubercles. Photo by J Busek s.n. Right, Bally’s drawing of the flower from Condollea 17 (October 1959) Fig. 2: Plant ex F Horwood s.n. – view of inner and outer corona lobes. Photo by U. Tränkle. Fig. 3: Plant ex F Horwood. Showing plan view of corona and rounded corners in tube; bases of corolla lobes bare; very faint small spots externally on tube. Photos by U. Tränkle.
they therefore constitute additional support that these northern plants are readily discernible from the Eyl population of P. migiurtinus. P. sphaericus grows at altitudes of 800 - 1300 m on limestone rubble slopes along the base of the inland (southern) side of the Ahl Mahdu Mountain range, as well as at the adjacent Buuraha Cal Mistcaat Mountains SE of Boosaaso (Specks pers. com. 16.1.2015). 28 - Asklepios 120 (2015)
Other Pseudolithos locality records The following are Lavranos collection records for what were considered at that time to be P. migiurtinus or forms thereof, with the taxa and place names that were in use for those specimens at that time; this Lavranos list was received from Roy Mottram on 16.11.2014. However, because it now appears evident that the southern and the northern populations do