Opilionomyces dicranolasmatis Santam., Enghoff, Gruber & Reboleira, 2017

Santamaria, Sergi, Enghoff, Henrik, Gruber, Jürgen & Reboleira, Ana Sofia P. S., 2017, First Laboulbeniales from harvestmen: the new genus Opilionomyces, Phytotaxa 305 (4), pp. 285-292 : 286-289

Opilionomyces dicranolasmatis Santam., Enghoff, Gruber & Reboleira , sp. nov. ( Figs 1−14 )

MycoBank MB 819441

Diagnosis:—Receptacle consisting of a single series of 9–18 superposed cells. Primary appendage copiously branched from the base where the lowermost cell seems to be randomly divided into irregular fragments of protoplast. Lower tier of perithecial wall cells (w 1

) as long as the three remaining tiers together.

Type: — TURKEY. Namrun (=Çamlıyayla), Mersin Prov., on 1 ♂ of Dicranolasma hoberlandti Šilhavı, 1956 (Opilionida, Dicranolasmatidae ), 2 June 1964, Franz Ressl leg. ( NMW 21440), C-F-95158, C-F!, holotype designated here; BCB-SS·E611b, BCB!, isotype designated here.

Etymology:—named after the host genus, Dicranolasma .

Thallus hyaline, except for the darkened reddish-brown foot. Basal cell, including the foot, about two times longer than broad. Total length (from base of foot to perithecial tip) 94−129(−144) μm. Receptacle consisting of a single series of 9–18 superposed, flattened cells. Perithecium solitary, borne on any of the 4 th –9 th receptacular cells (henceforth II p) and separated from it by a vertical to diagonal septum. Using the cell II p as reference, the receptacle may be described as divided into two parts; the lower part consists of a straight to variably curved pedicel of 4–8 cells, gradually widened upward; the upper part consists of 4–9 cells similar in breadth, laterally adnate to the perithecial dorsal side, except for the free 2–3 uppermost cells diverging from the perithecium and forming the support for the primary appendage.

Perithecium 41–54(–65) × 19–23(–33) μm, more or less ellipsoidal, with a broad venter and a short, slightly differentiated neck. Apex subacute, with four rounded and inconspicuous lips. Distal quarter of the perithecium free and diverging from main axis of the perithecium ( Fig. 6 ). Lower tier of outer wall cells (w 1) as long as the three tiers above (w 2-4) together. Three inner wall cells per row (p, arrowheads, Fig. 6 ) are clearly defined inside the tip of perithecium. Stalk-cell of perithecium ( VI) very small, sub-triangular in optical section. Perithecial basal cells (m, n, n’) well-distinguished ( Figs 4−5 ).

p

Primary appendage 93−145 μm of maximum length, if undamaged; as long as or longer than the remaining thallus; profusely branched from the broad and rather undefined base, including several poorly delineated cells, thin fragments of protoplast; some stripes probably arising by deterioration, as well as by fusion of walls, and a more visible but variably shaped triangular basal cell ( Figs 7−8 ).

Remarks:— The above description is based on the study of 47 mature and 67 immature thalli obtained from three species of Dicranolasma : 25 mature and 20 immature thalli from D. giljarovi Šilhavy 1966 , 2 mature and 2 immature from D. opilionoides (L. Koch 1867) , and 20 mature and 44 immature from D. hoberlandti . Most of the hosts (15 out of 18) are males, and 43 mature thalli and 67 immature thalli were found on this sex. Most of the fungi grow on pedipalps; their presence on chelicerae is sporadic. These specimens as well as other studied harvestmen showed many black spots on pedipalps, i.e., the darkened foot of fungal thalli, which means that several fungi were broken and had fallen off, whether due to the host’s behavior, the fixing liquid, or some other factor. Some samples come from pitfall traps, and it is well known that the preservation liquid of many traps may cause deterioration of the fungal thalli (W. Rossi pers. comm.).

There are no significant differences between thalli collected on different host species. Only, those found on D. hoberlandti ( Figs 2–3 ) are shorter than those found on other hosts ( Fig. 1 ).

Despite the abundance of material we have not been able to recognize antheridia with certainty. We have found trichogynes in different stages of development ( Figs 9–11 , tr), which suggests the existence of antheridia. The purpose of trichogynes is related to retaining the spermatia released from antheridia and to carrying the male nucleus to join the female nucleus located inside the carpogonial cell. In O. dicranolasmatis , the trichogyne or its remains ( Fig. 11 , tr) points towards the “undefined” area in the base of the appendage. Only in one thallus ( Fig. 9 ) we can see a rounded protuberance arising from the adjacent appendage cell near an apparently entire trichogyne. This protuberance is connected through a channel with cellular protoplast resembling something like a spermatium emerging from the efferent neck of a phialide ( Fig. 9 , arrow). This single observation, however, does not provide sufficient evidence for describing an antheridium, but nevertheless is fairly suggestive.

It seems appropriate to consider the peculiar structure of the appendage base as a species character, better than a genus character. We can compare it with a similar feature seen in Corethromyces minusculus Thaxt. ( Thaxter 1931, Santamaria 1997) where the appendage is dorsally enlarged by wall thickenings of poorly delineated cells.

The primary septum is located below the triangular basal cell of the appendage and may be detected by the slight indentation of outer edges and by some thickening of septum cell wall ( Figs 2 , 9–10, 12 , a). Sporelings ( Fig. 12 ) show a certain amount of displacement of the outermost edge of the primary septum (ring in the outer part of the thallus wall); the cell above the primary septum, the basal cell of primary appendage, appears distinctly elongated if compared with cells below and corresponds to the above-mentioned base of appendage, so characteristically “undefined”.

Disposition and length of ascospores inside the perithecium ( Fig. 6 , asc) suggest that there is only one ascogenic cell ( Tavares 1985: 74).

Position on hosts:— Typically on pedipalps, less frequently also on chelicera.

Additional collections examined: — TURKEY. Namrun (=Çamlıyayla), Mersin Prov., on 2 ♂♂ of D. hoberlandti , 2 June 1964, Franz Ressl leg. (NMW 21440), BCB-SS·E610, E612 (BCB!). Şile East, Istanbul prov., hills 5 Km South of Şile, on 2 (♂, ♀) of Dicranolasma giljarovi , 17 April 1966, Harald Schweiger leg., coll. number NMW 28524, BCB-SS·E571ad (BCB!). South Akcacoca, on coast N Düzce, forest, 300– 400 m.a.s.l., on 9 ♂♂ and 2 ♀♀ of D. giljarovi , 27 April to 10 May 1976, pitfalls, H. Korge leg., J. Martens collection (number 2943), BCB-SS·E605ak (BCB!). Uludağ, Bursa Prov., basal calcareous zone near Incaya, about 900 m. a.s.l., on 1 ♂ of Dicranolasma hoberlandti , 18 May 1964, Harald Schweiger leg., coll. number NMW 28525, BCB-SS·E609 (BCB!). GREECE. North Peloponnes, East of Mount Khelmós, 2 Km South of Zarúkhla, 1100 m.a.s.l., on 1 ♂ of Dicranolasma opilionoides , 23 September 2004, W. Schawaller leg., J. Martens collection (number 4158), BCB-SS·E604 (BCB!).

Figures

FIGURES 1–3. Opilionomyces dicranolasmatis. Mature thalli. (Fig. 1, SS·E605k; Figs 2–3, C-F-95158, holotype) (Abbreviations: I, basal cell of receptacle; a, primary septum; II , cell of receptacle bearing the perithecium.) Scale bars = 50 μm.

FIGURES 4–14. Opilionomyces dicranolasmatis. Figs 4–5. Detail of a perithecium at two different focusing levels; near focus in Fig. 4 showing the stalk-cell of perithecium (VI), the secondary stalk-cell of perithecium (VII), and two of the perithecial basal cells (n’, m) with respective rows of wall cells formed from them (wn’1–4, wm1–4); far focus in Fig. 5 showing the other perithecial basal cell (n) with the two rows of wall cells formed from it (w n) (the fourth tier, w n4, is out of focus). Fig. 6. Detail of a perithecium at middle focus showing ascospores (asc), cells VI and II p, and cells p (inner perithecial wall cells, arrowheads). Figs 7–8. Details of the base of primary appendage with basal cell (e). Fig. 9. Immature thallus showing a trichogyne (tr) in contact with a rounded protuberance arising from adjacent appendage cell (phialide?) (arrow, detail in upper-right corner), and primary septum (a). Fig. 10. Immature thallus showing the primary septum (a) and very young trichogyne (tr). Fig. 11. Upper part of a mature thallus showing a degenerate trichogyne (tr). Fig. 12. Sporeling showing the primary septum (a). Fig. 13. Immature thallus showing the perithecial initial cell or perithecial primordium (d) where the nucleus can be seen (nuc); cell II p is also labelled. Fig. 14. Immature thallus in a more advanced stage of development where cell d has been divided in cells h (lower cell which will form the sterile parts of perithecium, e.g. the wall) and i (upper cell which will form all fertile parts of perithecium including asci and trichogyne); cell IIp is also labelled. (Figs 4–5, 7, 11, SS·E571a; Figs 6, 9, SS·E605k; Figs 8, 12, SS·E571b; Figs 10, 14, SS·E612; Fig. 13, SS·E605b.) Scale bars = 20 μm.