Monolistra (Microlistra) jalzici, Prevorčnik & Verovnik & Zagmajster & Sket, 2010

Prevorčnik, Simona, Verovnik, Rudi, Zagmajster, Maja & Sket, Boris, 2010, Biogeography and phylogenetic relations within the Dinaric subgenus Monolistra (Microlistra) (Crustacea: Isopoda: Sphaeromatidae), with a description of two new species, Zoological Journal of the Linnean Society 159 (1), pp. 1-21 : 10-13

MONOLISTRA (MICROLISTRA) JALZICI SP. NOV.

( FIGS 3–5 )

Holotype: Adult male, 7.9 mm, Croatia, Istra Peninsula, springs in the drainage tunnel Čepic´, near Kršan, Labin; leg. B. Sket and S. Legovic´. Inv. No. ‘ Malacostraca 2240 ht’, partly dissected, preserved in ethanol, deposited in the collection of the OB BF UL.

Paratypes: Same data as holotype. Three adult females (one ovigerous, two non-ovigerous, 11.6– 6.4 mm). Collection of OB BF UL Inv. No. Malacostraca 2240 pt .

One paratype deposited in the Hrvatski prirodoslovni muzej (Croatian Natural History Museum), Zagreb, Croatia .

Etymology: The species is named after our good colleague Branko Jalzic´, a deserving Croatian caver and cave-fauna researcher.

Diagnosis: Microlistra species with short, but stout, densely setulose massive cones on its dorsal surface. Pleotelson irregularly nodular, with large lateral protuberances and uropod rudiments elevated on small elevations (‘socles’), projecting over pleotelson outline ( Fig. 4 ). Anterior coxae truncated; posterior ones blunt and slightly turned up distally.

Description of holotype: Male, 7.9-mm long. Body width 44% of body length. Head (cephalothorax) dorsally with transverse row of four conical processes. Pereonites I–VI each with one median and two lateral conical processes. Pereonite I with three, and pereonites II–VI each with two conical paramedian nodules on each side; protuberances on epimeral apex larger, gradually increasing in size from epimeron II–VI; protuberances on epimeron V–VI similar to median and lateral conical processes. Pereonite VII without lateral and epimeral processes. Pleonite I without lateral and epimeral nodules. Pleotelson width 150% of pleotelson length, highly vaulted, and its surface densely and irregularly covered with conical and rounded nodules. Only paired lateral conical processes (resembling those on epimeron VI) protruding remarkably over pleotelson outline, and followed by raised socles carrying uropod rudiments. Pleotelson ventrocaudal border without a groove, with a comparatively narrow dorsocaudal bulge reaching far beyond it. All large dorsal protuberances covered with thick mat of very long setules, except at the very base and apex.

Antenna I length 32% of body length; peduncle article 1 bent perpendicularly; 6 flagellar articles, articles 3–6 each with single, long aestethasc. Antenna II length about 40% of body length; 11 flagellar articles. Length ratio of peduncular articles and flagellum in antenna I 100: 73: 80: 135, in antenna II, 68: 100: 123: 191: 653.

Left mandible stout, incisor and lacinia mobilis both unicuspidate, bluntly rounded (spatulate); apical spine row of 13 spiniform processes on a long stalk; molar process with prominent serrations around smooth mesial surface. Right mandible without lacinia mobilis. Other mouth appendages and maxilliped as in type species, Monolistra (Monolistra) caeca Garstaecker ( Racovitza, 1910) .

Pereopod I propodus (article 6) width 36% of propodus length; merus (article 4) with two serrate spines at anterodistal angle; carpus (article 5) with two biserrate spines at posterodistal angle; propodus with three biserrate spines on posterior margin and two at posterodistal angle; setulose fringe near continuous on posterior margin of basis (article 2) to beginning of unguis (distal part of article 7, claw); setules lengths on ischium (article 3) about 50% of article width, diminishing towards unguis; setulose fringe also present on anterior margin of basis to merus, length of setules increasing towards merus; secondary unguis finely serrate. Pereopod II basis with three long plumose setae on anterior margin; merus with two serrate spines at anterodistal angle; carpus with one biserrate spine at posterodistal angle, and one on distal margin; propodus with two short serrate spines on posterior margin, one serrate spine at posterodistal angle, and one long plumose seta at anterodistal angle; setulose fringe present on posterior margin of distal third of ischium to beginning of unguis, nearly continuous on anterior margin of basis to unguis; secondary unguis finely serrate. Pereopod VII basis with one long plumose seta on anterior margin; merus with two serrate spines at posterodistal angle; carpus with one serrate spine at posterodistal angle, one biserrate spine at anterodistal angle, and two on distal margin; propodus with one serrate spine on posterior margin, one at posterodistal angle, and one long plumose seta at anterodistal angle; setulose fringe as in pereopod II, except setules shorter; secondary unguis finely serrate. Relative lengths of pereopods I, II, and VII: 33, 41, 48% of body length; length ratio of articles (coxa excluded) in pereopod I 100: 49: 31: 19: 54: 40, in pereopod II 100: 51: 32: 48: 53: 38 in pereopod VII 100: 91: 34: 53: 63: 33.

Pleopod I protopodite with fine long setules along internal and external margins, and two strong spines at internal angle; exopodite elliptical, with 7 plumose setae along terminal margin, and setules at proximoexternal angle; endopodite about half as wide and nearly as long as exopodite, parallel sided, with two plumose setae on rounded terminal margin and setules at proximo-internal angle. Pleopod II similar to I, but with more numerous plumose setae; endopodite as wide as exopodite, slightly widened distally, with 17 setae; appendix masculina distally curved and terminally blunt, its length 120% of endopodite length; exopodite with 9 plumose setae. Pleopod III exopodite elongate, subovoid, without respiratory area, with short transverse suture at the external margin, and with a trace of the same suture at the internal margin. Pleopod IV shape similar; respiratory area length 55% of exopodite length, surface 35% of exopodite surface. Pleopod V exopodite irregularly elliptical with thick sclerotized ridge along proximal half of external margin; three patches on intero-distal half densely scaled; respiratory area on intero-proximal half, its length 30% of exopodite length. Uropods vestigial, as in the subgenus type species Monolistra (Microlistra) spinosa Racovitza (1929) .

Description of paratypes: Females of 11.6, 8.2, and 6.4 mm in length; larger than male if adult; body width 67% of body length. Pleotelson dorsocaudal vault surpassing ventrocaudal pleotelson border to greater extent than in male.

Antenna I length 29–39% of body length; of between six and nine flagellar articles, articles 4–6 and 8, or 3–5 and 7, each with single, long aestethasc. Antenna II length 38–43% of body length, flagellum of between 10 and 12 articles.

Pereopod I spines and setulose fringe as in male, but propodus with between three and five biserrate spines on posterior margin, and two at posterodistal angle. Pereopod II spines and setulose fringe as in male, but basis with one or two long plumose setae on anterior margin; carpus with one or two biserrate spines at anterodistal angle, and one or two biserrate spines on distal margin; propodus with one or two short serrate spines on posterior margin. Pereopod VII spines and setulose fringe as in male, but basis with between two and five long plumose setae on anterior margin; merus with one or two biserrate spines at anterodistal angle; carpus with between one and three biserrate spines at anterodistal angle, one on distal margin and two at posterodistal angle; propodus with one or two short serrate spines on posterior margin. Relative length of pereopods I, II, and VII, 30–34, 36–40, and 43–50% of body length, respectively; length ratio of their articles (coxa excluded) in pereopod I 100: 47: 28: 13: 48: 35/100: 54: 37: 16: 57: 49/100: 54: 39: 19: 58: 48, in pereopod II 100: 49: 31: 45: 49: 34/100: 55: 34: 53: 61: 35/ 100: 79: 46: 67: 81: 60, in pereopod VII 100: 94: 39: 57: 64: 33/100: 93: 35: 58: 61: 32/100: 101:

39: 62: 64: 38.

Pleopods I and II as in male, but with different number of plumose setae: pleopod I with one or two and six or seven plumose setae; pleopod II with 13–18 and 8–11 plumose setae. Pleopods III and IV shapes as in male. Pleopods IV and V respirtory area length 54–63 and 32–42% of exopodite length, pleopod V respiratory area surface 26–41% of exopodite surface.

Distribution and ecology: Numerous specimens were found in small freshwater springs, appearing in the tunnel draining the karst polje (a large depression within karst) Čepićko polje, north of Labin, eastern Istra Peninsula, Croatia. They were accompanied by the large cirolanid isopod Sphaeromides virei virei (Brian) , and by an atyid cave shrimp Troglocaris sp. In the past, numerous cave salamanders, Proteus anguinus Laurenti ( Amphibia: Proteidae ), used to be washed up from the springs into the tunnel ( Sket, 1997). Some specimens of the new Monolistra were dorsally nearly black, presumably as a result of bacterial iron deposition.

Remarks: The pleopods of M. (Microlistra) jalzici sp. nov. are nearly identical to those of M. (Microlistra) pretneri Sket, 1964 . In most populations of the latter species, dorsal protuberances are present on pereonites; however, they are all of equal length, and are conical and smooth. We believe that prominent differences in dorsal sculpturing might play the role of a reproductive barrier, and therefore we consider M. (Microlistra) jalzici sp. nov. to be a true species, in accordance with the molecular tree and with the biological species concept.

Figures

Figure 3. Monolistra (Microlistra) jalzici sp. nov. tunnel Čepic´, Istra, Croatia, female 11.6 mm, obliquelateral view (SEM JEOL JSM-840A by K. Drašlar). * – *, median row of dorsal spines.

Figure 4. Monolistra (Microlistra) jalzici sp. nov., tunnel Čepic´, Istra, Croatia, dissected ovigerous female: MdbL, left mandible (apical part); MdbR, right mandible with palp (apical parts); Mx I, II, maxilla I and II (apical parts); Mxlp, maxilliped; PMxlp, maxilliped palp. Holotype male, 7.9 mm: A I, II, antennae I and II; F, frons: with ep, epistome and la, labrum; Plt, pleotelson, ventral view: with U, uropod rudiment on its socle.

Figure 5. Monolistra (Microlistra) jalzici sp. nov., tunnel Čepic´, Istra, Croatia, holotype male, 7.9 mm: Plp I–V, pleopods I–V; Pp I, II, VII, pereopods I, II, VII.