Rickia candelabriformis Santam., Enghoff, & Reboleira, 2016

Santamaria, Sergi, Enghoff, Henrik & Reboleira, Ana Sofia P. S., 2016, Hidden biodiversity revealed by collections-based research-Laboulbeniales in millipedes: genus Rickia, Phytotaxa 243 (2), pp. 101-127 : 105-107

Rickia candelabriformis Santam., Enghoff, & Reboleira , sp. nov. ( Figs 6–10 , 60 )

Mycobank MB 815402

Diagnosis:—Receptacle biseriate; a: 3, p: 4(–5). Cells I, a 1 and p 1 delineating a curious form reminiscent of a two-armed candelabrum. Only one antheridium on cell p

1

, with a long, strongly inwardly (towards the thallus) curved neck.

Type: — AUSTRALIA. Tasmania, St Columba Falls, 27.1 km 256’W St. Helens, S41º17’7.2” E147º55’33.7”, 335 m. a.s.l., eucalypt/ casuarinas woodland, on indeterminate Iulomorphidae ( Spirostreptida ), 7 March 2006, N.Scharff & T. Szüts leg., C-F-95089, C-F!, holotype designated here; BCB-SS ·E600a, c, BCB!, isotypes designated here.

Etymology:— candelabriformis , meaning “shape of candelabrum”, the ensemble of cells I, a 1 and p 1 resembles the shape of a simple candelabrum with only two arms.

Thallus hyaline to pale yellowish except for the dark brown foot, the trichogyne scar, and the septa separating the appendiculate cells from appendages. Total length 134–174 μm. Receptacle biseriate. Basal cell four times as long as broad, narrowly ovate, surrounded on both sides for about ¾ of its upper length by cells a 1 and p 1 from which it is separated by strongly oblique, nearly vertical septa. The outline in this part of the thallus is abruptly indented at the transition between cell I and both lower cells of the marginal series, resulting in the distinct shape from which the epithet of species has been derived ( Figs 6–7 , arrows).

Anterior series consisting of three cells ( Fig. 6 ). Cell a 1 broadly triangular in section, about 2.5 times as long as broad, never with appendages. Its upper side reaching the same level as the top of cell I. Cells a 2 and a 3 flattened, each giving rise to a flattened and elongated appendiculate cell bearing a secondary appendage. Cell a 3 bearing the perithecium and a very inconspicuous perithecial stalk-cell (cell VI) on its upper-inner corner ( Fig. 8 , VI).

Posterior series consisting of 4(–5) cells. Cell p 1 nearly identical in shape and size to cell a 1, but it is worth mentioning that it supports the unique antheridium of the thallus on its outer-upper corner, including a minute appendiculate cell and a bigger stalk-cell, both concolorous with the pale receptacle ( Figs 7, 9–10 ). Cell p 2 very variable in shape and size, with a secondary appendage with an appendiculate cell on its upper-outer corner. Cell p 3, which sometimes divides forming a p 4, usually lacks appendages or rarely bears only one; it varies greatly in size depending on whether it is undivided (then it is longer than broad) or if the additional p 4 is also formed, in which case both cells appear shortened. The upper cell of the series (p 4 or p 5) supports the primary appendage, including its dome-shaped basal cell, a constricted and dark brown septum, and the distal elongated cell, which is similar to any secondary appendage ( Fig. 8 , pa).

Antheridium 8–12 × 3–5 μm, typically isolated on p 1, above a minute triangular appendiculate cell, a bigger stalk-cell, and the terminal flask-shaped phialide ending in a rather long, strongly inwardly incurved efferent neck ( Figs 7,

9–10, an).

Secondary appendages, 21–43 μm, deteriorate easily, hyaline, soft, delicate, slightly expanded by pressure of coverslip, separated from respective appendiculate cells by dark brown and constricted septa ( Fig. 6 , sa).

Perithecium 65–82 × 27–32 μm, solitary, ovoid, entirely hyaline, except for the tan trichogyne scar present on the side where the short neck is slightly differentiated; apex blunt ( Fig. 7 , trs).

Discussion:— Some thalli differ from the above description in having two perithecia and a variable number of cells in the series, but these specimens are very uncommon and could be considered abnormal by damage and subsequent unusual cell divisions. This species may be compared with R. rhynchophora if we only look at the base of thallus, but remaining characters are very different. The sucker-like shape of the foot of a sporeling and of two immature thalli can be seen on the SEM image of Fig. 60 .

Position on host:— Thalli are found randomly along the body rings, legs and head, including antenna and clypeus.

Female hosts are highly infected on the first pairs of legs. Three thalli were found in a male gonopod (C-F-95099).

Notes on hosts:— The Australian fauna of Iulomorphidae is extremely poorly known, and numerous species and genera still await description. Even the delimitation of Iulomorphidae vis-à-vis Cambalidae is dubious (Enghoff et al.

2015). Eumastigonus (see also R. galatheae sp.nov.) is endemic in New Zealand (Korsós & Johns 2009).

Additional collections examined: — AUSTRALIA.SE QLD, Lamington NP near O’Reilly’s Gesthouse, rainforest, on Victoriocambala sp. ( Spirostreptida , Iulomorphidae ), 13–17April 2002, N.Scharff & S.Larsen leg., BCB-SS·E589ac, BCB-SS·E591 (BCB!). Tasmania, Newall creek, Franklin-Gordon Wild Rivers, N.P. 9.67 km 177’ Queenstown, Notophagus rainforest, S42º09’37.1” E145º32’20.1”, 159 m. a.s.l., on Iulomorphidae indet. ( Spirostreptida ), 14 March 2006, N.Scharff & T. Szuts leg., BCB-SS·E593ac (BCB!). Tasmania, Weldborough Pass Scenic Reserve, 28.6 Km 280WNW St Helens, Notophagus rainforest, S41º12’59.8” E147º56’18.2”, 480 m. a.s.l., on Iulomorphidae indet. ( Spirostreptida ), 6–7 March 2006, N.Scharff & T. Szuts leg., BCB-SS·E594 (BCB!). Tasmania, Cradle Mountain, Lake St Clair N.P., near Waldheim cabins, 22.6 Km 202SWS Moina, Notophagus rainforest, S41º38’28.5” E145º56’26.5”, 926 m. a.s.l., on Amastigogonus sp. ( Spirostreptida , Iulomorphidae ), 3–5 March 2006, N.Scharff & T. Szuts leg., BCB-SS·E597 (BCB!). NEW ZEALAND. Ak: Waitakere Ranges Regional Park, Kauri Grove Track, S36º57.795’ E174º30.876’, on Eumastigonus sp. ( Spirostreptida , Cambalidae ), 2 February 2011, A.Solodovnikov & L.Vilhelmsen leg., BCB-SS·E592ac (BCB!).

Rickia dendroiuli W. Rossi in W. Rossi & Balazuc ex W. Rossi ( Figs 52–53 )

This species was validated with designation of the holotype by Rossi (1986) to correct its absence in the original description ( Rossi & Balazuc 1977). The type material comes from Italy and was found on Cylindroiulus latzeli (Berlese 1884) (as Dendroiulus ) ( Julida , Julidae ). The authors compared their species with Rickia uncigeri Scheloske and mentioned many differences between them. On the basis of our studied material the number of cells for each series is 3(a), 11(m), and 8(p), which does not differ significantly from what was described in the protologue (3–4 a, 9–10 m, 7 p).

The species of Rickia parasitizing family Julidae , order Julida , constitute a group of closely related species: R. dendroiuli , R. laboulbenioides , R. pachyiuli , and R. uncigeri . Distinguishing these species may be difficult, and careful observation is needed. Only R. laboulbenioides is easily and readily distinguished from others by specific characters such as, for example, the shape and size of the primary appendage and the subtending cell. Rickia dendroiuli may be distinguished from R. pachyiuli and R. uncigeri by the median series of the receptacle. The median series of R. pachyiuli consists of 11–12 cells, of which 7–8 cells are located below the base of the perithecium, whereas in R. dendroiuli and R. uncigeri there are only two cells in this position. In R. dendroiuli , the upper part of the median series (approx. the 3–4 distal cells) clearly curves towards the posterior side of the thallus overlapping cell p 7 and causing the primary appendage to point obliquely in an angle of about 45º as to the perithecial axis ( Fig. 53 , arrow). This character is not mentioned in the original description although it is visible in the illustrations. We consider it important to distinguish R. dendroiuli from the other two species.

Rickia dendroiuli has been recorded from England (Berkshire) growing on Cylindroiulus punctatus (Leach 1815) ( Storey 2009) , but the several fine images of the fungus show that the species in question is R. laboulbenioides , not R. dendroiuli . The host of R. dendroiuli , C. latzeli , previously known as Dendroiulus latzeli , belongs to order Julida , family Julidae , and is largely widespread in Italy where it is endemic.

Position on host:—Many thalli on the anterior legs (pairs 1–12), sometimes also on the ventral parts of the corresponding body rings, a few thalli also found on legs further back (to the middle of the millipede’s body) and on the head, antennae and mouthparts ( Enghoff & Santamaria 2015).

Collections examined:— ITALY. Roma, Canale Monterano, on Cylindroiulus (Dendroiulus) latzeli (Berlese 1884) , 17 April 1976, W.Rossi leg., WR586 -paratype-. Veneto, Montello, between Treviso and Belluno, on C. latzeli , 2 October 2010, L. Bonato et al. leg.

Figures

FIGURES 6–10. Rickia candelabriformis. Figs 6–8. Mature thalli, arrows in Figs 6 and 7 indicate a diagnostic characteristic, from which the species takes his name. Fig. 9. Immature thallus. Fig. 10. Detail of antheridium. (Figs 6, 7, SS·E600a; Fig. 8, SS·E589a; Figs 9–10, SS·E593a.) FIGURES 11–15, Rickia galatheae. Figs 11–13. Mature thalli. Figs 14–15. Details of antheridia. (Figs 11, 14–15, SS·E598a; Fig. 12, C-F-95088; Fig. 13, SS·E595a.) (For interpretation of abbreviations see under materials and methods.) Scale bars for Figs 6–8, 11–13 = 50 μm; for Figs 9, 14 = 20 μm; for Figs 10, 15 = 10 μm.

FIGURES 60–66. SEM images. Fig. 60. Rickia candelabriformis, one immature thallus and two sporelings; the arrow points to the septum between the two cells of the primary appendage. Figs 61–65. Rickia gigas; in Fig. 61 a broken foot of a thallus above the scar left by another thallus purposely removed; in Fig. 62 detail of a perithecial apex; in Fig. 63 several thalli showing the flattened appearance of the lateral branches; in Fig. 64 a row of paired antheridia; in Fig. 65 a perithecium showing the two lower tiers of wall cells. Fig. 66. Rickia siddhartha, thalli where arrows point to septa between appendiculate cells and the upper cell of secondary appendages. (For interpretation of abbreviations see under materials and methods.) Scale bars Figs 60–62, 66. = 10 μm; for Fig. 63 = 50 μm; for Fig. 64 = 25 μm; for Fig. 65 = 20 μm.

FIGURES 52–59. Species of Rickia not described in this paper. Figs 52–53. Mature thalli of Rickia dendroiuli. Arrow in Fig. 53 points to the uppermost cell of posterior series, where a diagnostic character is shown (see text). Figs 54–55.Mature thalli of Rickia laboulbenioides. Figs 56–57. Mature thalli of Rickia pachyiuli. Fig. 58. Mature thallus of Rickia siddhartha. Fig. 59. Mature thallus of Rickia uncigeri. (Figs 52–53, WR586; Fig. 54, SS2686d; Fig. 55, SS2686e; Fig. 56, SS·E582b; Fig. 57, SS·E582c; Fig. 58, SS·E601b; Fig. 59, SS·E596c.) (For interpretation of abbreviations see under materials and methods.) Scale bars = 50 μm.