Rickia rhynchophora 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 : 118-122

Rickia rhynchophora Santam., Enghoff, & Reboleira , sp. nov. ( Figs 47–51 )

Mycobank MB 815409

Diagnosis:—Receptacle biseriate; a: 5, p: 7. Cells a 1–4 and p 1–4 arranged in a symmetrical, pinnate way along the main, vertical axis of the thallus. Perithecium narrowly ovoid, almost immersed in the receptacle, extending into a snoutlike, bent neck.

Type: — AUSTRALIA. SE Queensland, Lamington NP near O’Reilly’s Guesthouse, rain forest, on Trigoniulus sp. ( Spirobolida , Trigoniulidae ), 13–17 April 2002, N.Scharff & S.Larsen leg., C-F-92263, C-F!, holotype designated here; BCB-SS ·E588a, c, BCB!, isotypes designated here.

Etymology:— rhynchophora , meaning “bearing a nose”, referring to the snout-like apex of the perithecium extending above the thallus.

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 171–237 μm. Receptacle biseriate. Basal cell about two times as long as broad, kite-like in shape, forming a symmetrical base for cells a 1 and p 1 from which it is separated by strongly diagonal septa ( Fig. 47 , I).

Anterior series consisting of five cells ( Fig. 49 ). Cells a 1–4, together with cells p 1–4 of the opposite marginal series arranged symmetrically, diagonally in relation to main thallial vertical axis, with the outer edges pointing upwards, in a pinnate way, side by side, and separated by vertical, straight septa which follow the central axis of the thallus. The pattern of distribution of the appendages is: a 1 always with one appendage, a 2 without appendages; a 3 and a 4 variable, may or may not bear an appendage; a 5 very narrow and elongated bearing from top to bottom one appendage, one or two antheridia, and two or three appendages ( Fig. 51 ). Cell a 4 bears the perithecium and supports an inconspicuous, flattened and wedge-shaped perithecial stalk-cell (cell VI) on its upper-inner corner.

Posterior series consisting of 7 cells ( Fig. 49 ). Cells p 5–7 very narrow and difficult to distinguish and count because they appear closely connected to the dorsal perithecial wall. Cells p 1–2 without appendages, cells p 3–4 each with one appendage (often cell p 3 lacks this appendage), cell p 5 with 2–3 appendages, and cell p 6 with 3–4 appendages. Upper cell of the series (p 7) comparatively big, supporting the primary appendage with its dome-shaped, small, basal cell, a constricted and dark brown septum, and the distal elongated, filamentous cell ( Fig. 47 , pa), which is nearly identical to the secondary appendages.

Antheridia 16–18 × 5–6 μm, typically 1–2 on a 5 in fully mature thalli. In immature thalli they may be fairly abundant, up to seven associated with the different cells of the a and p series (more often a 4 and p 4, besides a 5). Antheridia hyaline, consisting of a minute trapezoidal appendiculate cell, a cylindrical stalk-cell, and the terminal flask-shaped phialide which bears a conspicuous, straight to curved efferent neck ( Figs 50–51 ).

Secondary appendages 14–34 μm, flask-shaped, with a rather inflated venter and a neck terminating in an obtuse apex, separated from their respective appendiculate cells by dark brown and constricted septa ( Fig. 48 ). Appendiculate cells immersed in the receptacle, vertically superposed.

Perithecium 89–147 × 20–31 μm, solitary, narrowly ovoid, with a narrow neck which extends into a snout-like, slightly laterally bent tip and a rounded apex; entirely pale, except for the tan trichogyne remnant (not only the usual scar) found on the anterior side ( Fig. 49 , trs); almost immersed and surrounded by the two receptacular series of cells.

Position on host:—Scantily distributed along the dorsal part of the body rings and in the 5 th leg.

Notes on hosts:— Trigoniulus is a large genus, and many species remain undescribed.

Discussion:— This species resembles R. candelabriformis in the biseriate condition of the thallus and the morphology of the lower receptacle, especially the ensemble of cells I, a 1 and p 1, but may be easily distinguished by several characters, especially by the shape of the perithecium and the snout-like tip in R. rhynchophora .

Rickia siddhartha Balazuc in W.Rossi & Balazuc ( Figs 58 , 66 )

The type material was described from Sri Lanka on Ktenostreptus lankaensis (Humbert 1865) ( Spirostreptida , Harpagophoridae ) ( Rossi & Balazuc 1977). This species is striking and very different from any other by the very elongated cell I, the reduced number of receptacle cells (2a, 1m, 3p), and by the free and elongated cell p 3 which forms a lateral appendage-like prolongation. The material we had the opportunity to study is from the locus classicus and has exactly the same collecting data as the material used to describe the species. In the SEM image ( Fig. 66 ) we can see the smooth appearance of the base of appendages (arrows), a characteristic also observed on SEM preparations of other species ( Fig. 60 , arrow). This may indicate that the more rigid and broad condition of wall cells in these areas of thalli (darkened basal septa in appendages) are more resistant to the critical point drying during preparation of SEM samples.

Ktenostreptus lankaensis is a large species, endemic in Sri Lanka.

Position on host:—Thalli were found all over the host, especially in the ventral part of the body.

Collections examined:— SRI LANKA. Sabaragamuwa, Prov. Deerwood Kuruwita, 6 mls NNW Ratnapura, Loc. 90 III, on Ktenostreptus lankaensis , 18–21 February 1962, Lund University Ceylon Expedition 1962, Brick-Andersson- Cederhom leg., isotype slide borrowed from W.Rossi collection. Ibidem, BCB-SS·E601ac (BCB!) and C-F-95090 (CF!) (host in the Lund University Zoology Museum).

Rickia uncigeri Scheloske ( Fig. 59 )

Described on Unciger foetidus (Koch 1838) from Germany ( Scheloske 1969) and reported later from Poland ( Majewski 1974), this species should be compared with the other species parasitizing Julidae , i.e., R. dendroiuli , R. laboulbenioides and R. pachyiuli , as mentioned above. Rickia uncigeri has triseriate thalli, without very striking characters, except may be those concerning the median series which consists of cells strongly narrowed towards the apex, following the dorsal wall of perithecium until near its apex.

Unciger foetidus is widespread in Central and Eastern Europe.

Position on host: — May occur all over the body but preferentially on the ventral side of head, as well as the anterior body rings and legs ( Scheloske 1969, Majewski 1974, Enghoff & Santamaria 2015).

Collections examined:— DENMARK. Dania, SZ PG64, Sorø Kristiansminde, 55º25’09”N 11º35’11”E, on Unciger foetidus , 24 July 2013, Malene Månsson leg., BCB-SS·E596ac (BCB!).

Figures

FIGURES 47–51. Rickia rhynchophora. Figs 47, 49. Mature thalli. Fig. 48. Detail of a secondary appendage.Fig. 50. Detail of antheridia. Fig. 51. Secondary appendages and antheridia with their appendiculate cells arranged laterally to cell a 5. (Figs 47–48, 50–51, SS·E588a; Fig. 49, C-F-92263.) (For interpretation of abbreviations see under materials and methods.) Scale bars Figs 47, 49 = 50 μm; for Figs 48, 50–51 = 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.

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.