Alpioniscus fragilis (Budde-Lund, 1909)

Taiti, Stefano, Argano, Roberto, Marcia, Paolo, Scarpa, Fabio, Sanna, Daria & Casu, Marco, 2018, The genus Alpioniscus Racovitza, 1908 in Sardinia: taxonomy and natural history (Isopoda, Oniscidea, Trichoniscidae), ZooKeys 801, pp. 229-263: 229

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Alpioniscus fragilis (Budde-Lund, 1909)


Alpioniscus fragilis (Budde-Lund, 1909)  Figs 1, 2, 3, 4, 18, 19

Alpioniscus fragilis  ; Taiti and Argano 2011: 166 (for previous records and references; nec Grotta del Caprone Tyson, p. 167).

Material examined.

Prov. Nuoro: 5 ♂♂, 16 ♀♀, 1 juv. (MZUF 9770), Grotta del Bue Marino, c.n. 12 Sa/NU, 40°14'55.72"N, 9°37'24.80"E, Cala Gonone, Dorgali, on cave walls, 25.IV.2012, leg. S. Taiti, P. Dore and S. Dessena; 1 ♂, 4 ♀♀ (MZUF 9826), same locality, date and collectors, under submerged stones; 1 ♀ (MZUF 9774), Grotta Pisanu or Gurennoro, c.n. 215 Sa/NU, 40°17'56.40"N, 9°33'05.30"E, 142 m, Gurennoro, Dorgali, 17.III.2014, leg. P. Magrini; 2 ♂♂, 1 ♀, 15 juvs (MZUF 9777), Grotta Elighes Artas, c.n. 907 Sa/NU, 40°14'20.3"N, 9°28'49.8"E, 360 m, Oliena, 25.IV.2013, leg. P. Marcia and S. Taiti; 1 ♂, 2 juvs (MZUF 9778), same locality, 15.I.2012, leg. P. Marcia; 1 ♂, 2 ♀♀, 3 juvs (MZUF 9779), same locality, 25.XII.2012, leg. G. Mulas; 2 ♂♂, 4 ♀♀, 2 juvs (MZUF 9780), Grotta Su Bentu, c.n. 105 Sa/NU, 40°15'18.23"N, 9°29'6.52"E, Lanaittu, Oliena, 3.XII.2011, leg. P. Marcia; 5 ♂♂, 3 ♀♀ (MZUF 9781), same locality, 6.I.2013, leg. P. Marcia; 2 ♀♀, 1 juv. (MZUF 9782), same locality 11-14.IX.2012, leg. P. Marcia and Astronauts; 1 ♂, 2 ♀♀ (MZUF 9783), same locality, 4.XII.2011, leg. P. Marcia; 4 ♂♂, 6 ♀♀, 9 juvs (MZUF 9784), Grotta S’Istampu de Sas Ballas, c.n. 106 Sa/NU, 40°15'20.82"N, 9°29'13.72"E, Oliena, 30.XII.2012, leg. P. Marcia; 4 ♀♀ (MZUF 9785), Grotta sa Seneppida, n.c.n., sa Seneppida, Orgosolo, 13.I.2013, leg. E. Dallocchio; 4 ♂♂, 8 ♀♀, 6 juvs (MZUF 9823), Voragine di Tiscali, c.n. 88 Sa/NU, 40°14'12.23"N, 9°29'6.52"E, Oliena, 23.X.2011, leg. P. Marcia. Prov. Ogliastra: 2 ♀♀ (MZUF 9772), Grotta Lovettecannas, c.n. 2642 Sa/OG, 40°08'33.72"N, 9°34'35.35"E, Baunei, 1.IV.2013, leg. P. Marcia; 1 ♂, 1 ♀ (MZUF 9773), Grotta di Baccherutta, c.n. 1008 Sa/OG, 40°04'5.22"N, 9°37'34.54"E, Baunei, 14.III.2009, leg. C. Onnis and N. Ibba; 1 ♂ (MZUF 9786), Grotta Piggios de Jana, n.c.n., Tauledda, Codula del Flumineddu, Urzulei, 28.X.2012, leg. C. Corongiu; 1 ♂ (MZUF 9787), Grotta Sa rutta e Mannaresuru, c.n. 2267 Sa/OG, 40°07'44.64"N, 9°26'49.99"E, Urzulei, 15.VII.2012, leg. P. Marcia; 4 ♂♂, 14 ♀♀ (MZUF 9788), same locality, 7.X.2012, leg. P. Marcia; many ♂♂ and ♀♀ (MZUF 9789), Grotta Sa Rutta 'e s’Edera, c.n. 588 Sa/OG, 40°05'51.3"N, 9°27'22.5"E, 950 m, Fennau, Urzulei, 23.IV.2012, leg. R. Argano and S. Taiti; 1 ♂, 6 ♀♀, 5 juvs (MZUF 9790), Grotta Su Palu, c.n. 1988 Sa/OG, 40°10'38.23"N, 9°33'50.53"E, 185 m, Codula Ilune, Urzulei, 8.XII.2012, leg. P. Marcia; 1 ♀ (MZUF 9775), Grotta Su Molente, c.n. 966 Sa/OG, 40°13'00.90"N, 9°36'10.95"E, Codula Ilune, Dorgali, 9.XI.2013, leg. M. Marrosu; 1 ♀ (MZUF 9807), same locality, 10.XI.2013, leg. E. Seddone; 4 ♂♂, 7 ♀♀ (MZUF 9771), Grotta Sos Cicinderos, n.c.n., Baunei, 7.VII.2013, leg. C. Onnis and M. Papacoda; 1 ♀ (MZUF 9791), Voragine Tesulali, c.n. 2681 Sa/OG, 40°07'42.14"N, 9°34'50.82"E, Baunei, 26.II.2012, leg. C. Onnis; 7 ♂♂, 19 ♀♀ (MZUF 9792), same locality, 10.II.2013, leg. C. Onnis; 1 ♂, 1 juv. (MZUF 9793), Grotta Su Tufu de Mangalistru, c.n. 422 Sa/OG, 40°06'17.28"N, 9°39'09.03"E, Baunei, 25.III.2012, leg. C. Corongiu; 1 ♀ (MZUF 9794), Grutta 'e S’Arena, c.n. 673 Sa/OG, 39°51'04.29"N, 9°27'44.43"E, Taquisara, 22.V.2013, leg. C. Onnis and P. Marcia; 1 ♂, 1 ♀ (MZUF 9798), same locality, 15.IX.2013, leg. C. Onnis and J. Costantino; 4 ♂♂, 5 ♀♀ (MZUF 9795), Grotta Istirzili, c.n. 50 Sa/NU, 40°04'49.50"N, 9°37'13.40"E, II..2013, leg. C. Onnis; 4 ♂♂, 7 ♀♀, 2 juvs (MZUF 9796), same locality, 12.V.2013, leg. C. Onnis; 3 ♂♂, 8 ♀♀ (MZUF 9797), Grotta S’erriu Mortu, n.c.n., Punta Giradili, Baunei, 7.VII.2013, leg. C. Onnis and M. Papacoda; 1 ♀ (MZUF 9799), Sa Grutta de su Coloru, c.n. 670 Sa/OG, 39°50'54.20"N, 9°27'34.68"E, Gairo Taquisara, 15.IX.2013, leg. C. Onnis and J. Costantino; 1 ♀ (MZUF 9801), same locality, 21.VIII.2013, leg. C. Onnis; 2 ♂♂, 21 ♀♀ (MZUF 9800), Lequarci or Lecorci Falls, Santa Barbara, Ulassai, 39°47'29.2"N, 9°27'11.6"E (WGS84), 560 m, under big stones outside cave, 28.III.2016, leg. R. Argano and S. Taiti. Prov. Cagliari: 1 ♂, 1 ♀, 2 juvs (MZUF 9824), Grotta Gospuru, c.n. 148 Sa/CA, 39°31'48.31"N, 9°26'13.21"E, 100 m, Baccu Gospuru, Armungia, IV.2012, leg. C. Onnis; 1 ♀, 2 juvs (MZUF 9776), Grotta Su Pittiolu de Gospuru, c.n. 1865 Sa/CA, 39°31'59.65"N, 9°26'04.41"E, 125 m, Baccu Gospuru, Armungia, 5.X.2008, leg. C. Onnis and N. Ibba; 2 ♂♂, 2 ♀♀ (MZUF 9825), same locality, 6.III.2011, leg. P. Marcia; 8 ♂♂, 15 ♀♀, 7 juv. (MZUF 9802), Grotta Su Fummu, n.c.n., San Nicolò Gerrei, 1.V.2012, leg. C. Onnis; 1 ♂, 12 ♀♀ (MZUF 9803), same locality, 17.III.2013, leg. C. Onnis; 2 ♂♂, 5 ♀♀ (MZUF 9804), Risorgenza Sa Gisterra, n.c.n., 39°30'08.4"N, 9°19'05.2"E, San Nicolò Gerrei, IX.2012, leg. C. Onnis; 2 ♀♀ (MZUF 9805), same locality, 20.IV.2013, leg. C. Onnis, R. Argano and S. Taiti; 3 ♂♂, 9 ♀♀ (MZUF 9806), Sa Rutt’e Scusi, c.n. 602 Sa/CA, 39°29'42.20"N, 9°24'18.00"E, Villasalto, V.2013, leg. C. Onnis.


Maximum length: ♂, 9 mm; ♀, 14 mm. Colourless body, pleon narrower than pereon (Fig. 1A). Dorsal surface distinctly granulated with ovoid scale-setae as in Fig. 1B. Many gland pores on lateral margins of pleonites 4 and 5, telson, lateral surface of uropodal protopods, and some scattered pores on dorsal surface of uropodal exopods (Fig. 1E). Cephalon (Fig. 1C, D) with suprantennal line V-shaped with rounded middle part; antennal lobes quadrangular, obliquely directed outwards with concave dorsal surface. Eyes absent. Posterior margin of pereonite 1 and 2 straight, and of pereonites 3-7 progressively more concave (Fig. 1A). Pleonites 3-5 with very short posterior points (Fig. 1A, E). Telson (Fig. 1E) approx. twice as wide as long; distal part with concave sides and very broadly rounded apex. Antennula (Fig. 1F) with second article distinctly shorter than first and third; third article distally enlarged and bearing 12-13 apical aesthetascs. Antenna (Fig. 1G) with fifth article as long as flagellum; flagellum of 10-13 articles with four groups of aesthetascs. Mandibles with one free penicil and one short molar penicil in the right (Fig. 2A) and three free penicils in the left (Fig. 2B). Maxillula (Fig. 2C) outer branch with 4 + 7 teeth, apically entire, and one slender setose stalk; inner branch with three long penicils. Maxilla (Fig. 2D) with setose and bilobate apex, inner lobe smaller. Maxilliped (Fig. 2E) basis with outer margin distally oblique and setose; palp stout, apically with tuft of setae and three tufts of setae on medial margin, basal article with two setae; endite narrow, with two apical stout setae and a large penicil. Pereopods with setose dactylar seta distally bifid (Fig. 3A), pereopod 7 with water conducting system on basis, ischium and merus. Uropod (Fig. 1E) with endopod distinctly shorter than exopod, endopod inserted proximally to exopod.

Male. Pereopod 1-4 (Fig. 3A) with carpus and merus bearing numerous short scales on sternal margin. Pereopod 7 (Fig. 3B) ischium with straight sternal margin covered with short setae; merus with three lobes proximally. Genital papilla (Fig. 3C) with a rounded tip. Pleopod 1 (Fig. 3C) exopod triangular with acute apex; endopod enlarged at base, distal part narrow with almost parallel sides and bearing an apical seta. Pleopod 2 (Fig. 4A) exopod triangular with convex outer margin and a small apical seta; endopod of two articles, longer than exopod, first article approx. three times longer than second, second article bearing distally rounded lobe and strong seta subapically cleft. Pleopod 3-5 exopods subtriangular with apical seta (Fig. 4 B–D).


The species seems to be widely distributed in the central-eastern and south-eastern karstic areas of Sardinia. The species is mainly terrestrial even if it occasionally occurs also in water.


This species was described by Budde-Lund (1909) as Titanethes (Alpioniscus) fragilis  from a Sardinian cave on material collected by Forsyth Major. No name for a specific cave was mentioned. However, considering that Forsyth Major discovered some troglobiotic species of different invertebrates during a digging campaign in caves of the Orosei Gulf, Casale et al. (2009) suggest that the cave explored by Forsyth Major most likely was the Grotta dell’Arciprete (= Grotta di Toddeitto) or one cave nearby in the same kastic area., e.g., Grotta del Bue Marino. The species is here redescribed on specimens from this last cave.