Lactuca denaensis N. Kilian & Djavadi, 2012

Kilian, Norbert, Djavadi, Seyyedeh Bahereh & Eskandari, Majid, 2012, Two new mountainous species of Lactuca (Cichorieae, Asteraceae) from Iran, one presenting a new, possibly myrmecochorous achene variant, PhytoKeys 11, pp. 61-77 : 62-66

Lactuca denaensis N. Kilian & Djavadi sp. nov. Fig. 1 3C; Tuisl 1968: t. 2, fig. 12-13 = Tuisl 1977: t. 201, fig. 9-10 under Lactuca polyclada (achene, aspect and cross section)

Lactuca polyclada sensu Boissier (1846: 10, 1875: 812) p.p. et Tuisl (1968: 606, 1977: 190-191) p.p., non sensu lectotypi.

Diagnosis.

Habitually similar to Lactuca rosularis but clearly distinguished by the rosette leaves being undivided (instead of lyrately to irregularly pinnatifid to pinnatisect), the involucre being 10-12 mm (instead of 6-9(-10) mm) long, the achenes having a 4-5 mm (instead of 2.2-3 mm) long corpus, a 0.4-0.9(-2) mm (instead of (1.1-)3-5.3 mm) long beak and a 5-6 mm (instead of 2.5-3 mm) long pappus.

Holotype.

[Iran, Kogiluyeh & Boyer Ahmad], in glareosis alpis Kuh-Daëna, fl. lutescens, 14 Jul 1842, Kotschy Pl. Pers. autral. 662 (G-BOIS G00330211, specimen annotated by Beauverd in 1910, see CHG 2012); selected isotypes: B 100426936, M 0030847 [p.p., two rosulate plants on the left], G [3 sheets], MO 6264530 [p.p., rosulate plants on the left and right], P 00750254 [p.p., left plant], P 00750251 [p.p., second bottom right rosulate plant], P 00750252 [p.p., first bottom right rosulate plant], P 00750253 [p.p., three rosulate plants at the bottom], WAG 0004075 [p.p., sterile leaf rosette on the left].

Description.

Perennial rosulate herb, with a woody subterranean caudex, rosette shoots often on vertical subterranean axes vested with cataphylls below the sometimes somewhat elongate rosette, acaulescent to usually very shortly caulescent and less than 5 cm tall ( Fig. 1A ), rarely to c. 15 cm. Stem one per leaf rosette, usually not or little projecting above the leaf rosette. Rosette leaves ( Fig. 1A ) obovate to spatulate, tapering towards base, 2-7 × (1-)1.5-3.2 cm, somewhat glaucous; base semiamplexicaul, margin ± densely dentate and denticulate, apex rounded to, more rarely, subacute. Synflorescence corymbosely paniculiform, condensed through conspicuously short axes, of c. 6-20 capitula ( Fig. 1A, G ); peduncles 0.4-0.7 cm long. Capitula with c. 10-14 flowers. Involucre ( Fig. 1B-F ) narrowly cylindric at anthesis, 10-12 mm long, not elongating during maturation; outer phyllaries imbricate, outermost ± narrowly ovate, c. 2 mm long, following ones gradually longer, lanceolate, the longest up to c. 1/2 as long as inner ones; inner phyllaries linear-lanceolate, 7-8, ± in one row, subequal in length, with ± narrow scarious margin. Receptacle flat to slightly convex, naked. Flowers with corolla yellow, ligule 6.7-7.5 mm, tube 5-5.5 mm long; anther tube without appendages 3.2-3.5 mm, basal appendages c. 0.4-0.6 mm, apical appendages 0.3-0.4 mm long; style arms 2.8-3.2 mm long. Achenes ( Fig. 1G, 3C ) homomorphic, including beak 4.8-5.7 mm long; corpus 4-5 mm long, up to 1.1-1.3 mm in diam., slender-obovoid, compressed, apex contracted into a stout, easily detachable beak c. 0.4-0.9(-2) mm long; achene body apart from the two lateral ribs with 1 similarly strong median rib on either side, rarely dorsally with 2 equally strong ribs, secondary ribs missing; achene surface ± smooth, brown. Pappus simple, without an outer series of minute hairs, setae thin, white, 5-6 mm long, persistent. - Flowering and fruiting: July to September.

Notes.

Boissier (1846) described a new species, Lactuca polyclada , based on two collections (no. 603 and 662) made by T. Kotschy in the Zagros mountains, in the first half of July 1842. Coming from the village Dozdkurd ( Edmondson and Lack 2006), Kotschy collected the material on the upper slopes of the "Kuh Daena"[= Kuh e-Dena, c. 30°56'N, 51°28'E; summit c. 4448 m, see Wikipedia (2012), situated in the present-day province Kogiluyeh & Boyer Ahmad of Iran]. According to Kotschy’s original labels present on the sheets in the Boissier herbarium in Genève (G-BOIS), the collection Kotschy 603 was collected on 10 July and Kotschy 662 on 14 July 1842. The entire material of Kotschy’s gatherings from S Iran was revised by Boissier and subsequently edited and distributed by R. Hohenacker in his series of exsiccatae "Plantarum Persiae australis siccatarum species 440, collectae a Th. Kotschy, determinatae a Dre E. Boissier, editae a R. F. Hohenacker" ( Triebel and Scholz 2001+; Edmondson and Lack 2006). Duplicates are present today in many herbaria. The material of Lactuca polyclada was distributed as a single item under the united numbers "603. 662." and with a single collecting date cited as "14 Jul 1842" on the printed label. The syntypes in Boissier’s herbarium as well as the duplicates distributed by Hohenacker in this series of exsiccatae as no. "603. 622." contain two morphologically distinct elements: (a) small leaf rosettes with usually very short, branched, slender to capillaceous flowering axes; (b) almost leafless, from base on divaricately and intricately branched, conspicuously inflated flowering axes. Apparently it has been taken as evident by Boissier and later workers that both elements represent different forms or stages of development of the same species. This assumption is backed by the leaves, which are fairly similar in colour, size, shape and denticulation of the margin in both elements, as well as by the existence of a plant with exceptionally well developed flowering shoots, approaching those of Kotschy 603, among the material of Kotschy 662 (on G00330211, the holotype sheet of Lactuca denaensis ). Boissier (1846: 10) expressed this hypothesis in the following way: "panicula corymbosa intra folia subsessili ... Post anthesin saepe panicula valde augetur, ramosissima fit semipedalis ramis elongatis intricatis dichotomis spongiose incrassatis, sed haec forma monstrosa est, nam in ea nunquam achenia perfecta observavi." ["with a corymbose panicle subsessile among the leaves ... after anthesis panicle often strongly enlarged, very much branched, becomes half a foot long, with elongate, intricate, dichotomous, softly inflated branches, but this is a monstrous form, because I never have observed a perfect achene in it."]. Tuisl (1977: 191) considered the two elements as different developmental stages: "caulis florifer abbreviatus, fructifer 10-30 cm longus" ["stems at anthesis very short, in fruit 10-30 cm long"].

Beauverd (1910: 131-132), in contrast, came to the conclusion that the syntypes of Lactuca polycalda in the herbarium of Boissier (G-BOIS) represent two entirely different species and correctly distinguished them. Beauverd (1910: 131) consequently restricted the name Lactuca polyclada to "K[otsch]y 603 solum! excl. No. 662 et descr. achen.," and formed the new combination Cicerbita polyclada (Boiss.) Beauverd for the taxon with divaricately branched inflated stems, smaller involucres, bluish flowers and a pappus with an outer row of minute hairs. Mature fruits of Cicerbita polyclada , missing in Kotschy 603, are known through a collection of T. Strauss (at B, see Appendix). They are illustrated here for the first time and show further differences between the two species, in particular with respect to the prominence of the ribs and shape and structure of the body apex (compare Fig. 2C and D-E ). For a summary of the differences see Table 1 .

According to Art. 7.11 of the Vienna Code, Beauverd’s restriction of the name to Kotschy 603 does not, however, constitute a lectotypification, because he did not use "the term ‘type’ (typus) or an equivalent" ( McNeill et al. 2006). Later authors apparently neglected Beauverd’s rectification and we are also not aware of any lectotypification of Boissier’s name. In accordance with Art. 9.12 ( McNeill et al. 2006) and in this way maintaining the only unequivocal use of the name as established by Beauverd (1910: 131) for the species placed by him in Cicerbita , we formally lectotypify Lactuca polyclada Boiss. following his restriction: Cicerbita polyclada (Boiss.) Beauverd in Bull. Soc. Bot. Genève 2: 131. 1910 ≡ Lactuca polyclada Boiss., Diagn. Pl. Orient., ser. 1, 7: 10. 1846. - Lectotype (designated here): [Iran, Kogiluyeh & Boyer Ahmad], in glareosis ad latera septentr. m. Kuh-Daëna, flos caeruleus, 10 Jul 1842, Kotschy Pl. Pers. autral. 603 (G-BOIS G00330212 [2 sheets annotated by Beauverd in 1910], see CHG 2012).

The second species admixed by Boissier under the name Lactuca polyclada with a usually very short or almost missing flowering stem, yellow flowers, a pappus without an outer row of minute hairs and the achene anatomy as illustrated by Tuisl (1968: t. 2, fig. 12-13 = 1977: t. 201, fig. 9-10) was left by Beauverd without a legitimate name. We have named and described it therefore here as Lactuca denaensis , the name being typified with the syntype "Kotschy 662" of Lactuca polyclada Boiss. in Boissier’s herbarium. Since Kotschy’s both collections no. 603 and 662 were combined by Hohenacker in his series of exsiccatae into a single unit of which each set usually contains both elements, isotypes are present in numerous herbaria. The corresponding exsiccatae sheets with the admixed material of Cicerbita polyclada and Lactuca denaensis carry the printed label "Th. Kotschy, Pl. Pers. austr. Ed. R. F. Hohenacker. 1845 // 603. 662. Lactuca polyclada / Boiss. n. sp. // In glareosis alpis Kuh-Daëna. D. 14. Jul. 1842. / Pl. lactescens." They are usually filed under Lactuca or Cicerbita polyclada , respectively, or, sometimes erroneously under Cephalorrhynchus polycladus (Boiss.) Kirp. The latter name is not a further homotypic synonym of Lactuca polyclada , but actually based on Zollikoferia polyclada Boiss., which represents a different mountainous species distributed from E Iran and Afghanistan to Central Asia, also with intricately and divaricately branched stems. Habitually, the latter species can readily be distinguished by its indurate and never inflated stems and branches; also it is not present in the Zagros mountains.

Distribution and habitat.

As far as we know, Lactuca denaensis is restricted to the higher elevations, probably above 3000 m, of Kuh e-Dena in the Zagros mountains of SW Iran ( Fig. 4 ). From the rare material with subterranean parts preserved (e.g. on the sheets MO 6264530 and P 00750252 with isotypes), showing a subterranean caudex producing several cm long shoots vested with cataphylls below the leaf rosettes, it can be concluded that the species is a scree plant.

Additional specimen seen: Iran. Kogiluyeh & Boyer Ahmad: Dena [c. 30°56'N, 51°28'E], 3300 m, Sep 1955, Remaudière 5252E (IRAN 10625).

Etymology.

Lactuca denaensis is named after the Kuh e-Dena massif of the Zagros mountains, where the only two collections known to us come from.

Morphological affinities and delimitation.

Morphological comparison shows that Lactuca denaensis is most similar to Lactuca rosularis . Both share the rosulate habit with a woody caudex, glaucous leaves and small yellow-flowered capitula but also the compressed, beaked achenes (compare Fig. 3B and C ), characterised by 4 (only exceptionally 5) similar and strongly prominent main ribs (two lateral and one median on either side, exceptionally dorsally 2) and a simple pappus without an outer series of minute hairs (see also Table 1 ).

Preliminary conservation status.

Lactuca denaensis is known only from the higher elevations of the Kuh e-Dena massif, which is part of a Protected Area, possibly also including the populations of the species. The species seems to be rare, since only two collections are known to us, but it has to be taken into account that it is rather inconspicuous. Lactuca denaensis must currently be assessed as Data Deficient ( IUCN 2001) and an assessment of its populations in the field is strongly desirable.

Figures

Figure 1. Lactuca denaensis - A habit, acaulescent form B-F capitula, all to the same scale, before flowering (B-D), with faded flowers (E), after flowering (F); G details of synflorescence, one capitulum at fruiting. - All from Remaudiere, 5252 E (IRAN 10625)

Figure 2. Lactuca hazaranensis - A habit, left plant of holotype sheet B-G capitula, all to the same scale, before flowering (B-C), at fruiting (D-E), after fruiting (F-G); H plant in natural habitat A-G from the holotype H plant in the natural habitat at the type locality; photograph by M. Eskandari, 10 Aug 2010.

Figure 3. Achenes of the Lactuca rosularis group and Cicerbita polyclada - A, F-I Lactuca hazaranensis; complete achene (A); achene after loss of easily detachable beak, dorsal view (F); ventral view (G); longitudinal section of achene showing two segments, proximal large segment with embry, distal small segment solid with yellow tissue (H); embryo (I); B Lactuca rosularis C Lactuca denaensis D-E Cicerbita polyclada, complete achene (D) and longitudinal section of distal portion showing apical cavity (E). - A-D and F-H each to the same scale A, F-I from the holotype at IRAN B from Rechinger 55980 B, C from Kotschy 662 (B 100426936) D-E from Strauss 14091 (B 100312952)

Figure 4. Distribution of Lactuca hazaranensis (circles) and the related species Lactuca rosularis (squares) and Lactuca denaensis (rhomb, actucal position as indicated by arrow), as well as of Cicerbita polyclada (triangles). - Georeferenced map based on the known collections (see Appendix and supplemented by collection cited in Kirpicznikov 1964 and Tuisl 1977) and generated with DIVA-GIS (Hijmans 2011) using an adaptation of the SRTM 90 m digital elevation data (CGIAR-CSI 2004).