Stammericaris destillans, Bruno & Cottarelli & Hauffe & Rossi & Obertegger & Grasso & Spena, 2017

Bruno, Maria Cristina, Cottarelli, Vezio, Hauffe, Heidi Christine, Rossi, Chiara, Obertegger, Ulrike, Grasso, Rosario & Spena, Maria Teresa, 2017, Morphological and molecular analyses of epikarstic Parastenocarididae (Copepoda: Harpacticoida) from two Sicilian caves, with description of a new Stammericaris, Zootaxa 4350 (2) : 255-261

Stammericaris destillans sp. nov.

( Figs. 2 –5, 11, 12)

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Type locality. Italy, Sicily, Palermo province, Molara Cave (cadastral number: Si Pa 53), two rimstone pools (pools 2, 3) and two drip funnels .

Type material. Holotype: male, dissected, mounted on one slide labelled: “ Stammericaris destillans holotype: male” ( NHMUK 2017. 58 ), pool number 1, 25/X/2012. Paratypes: one female, dissected, mounted on slide labelled: “ Stammericaris destillans paratype: female” (NHMUK 2017. 59), pool number 3, 04/IV/2014; one female, undissected, mounted on slide labelled: “ Stammericaris destillans paratype: female” (NHMUK 2017. 60), pool number 3, 25/X/2012; one male, dissected and mounted on slide labelled: “ Stammericaris destillans paratype: male” (NHMUK 2017. 61), pool number 3, 04/IV/2014; one male, undissected, mounted on slide labelled: “ Stammericaris destillans paratype: male” (NHMUK 2017. 62), pool number 2, 04/IV/2014. All material collected by RG and MTS.

Etymology. The species epithet is the present active participle of the Latin verb destillo (“drip or trickle down), because the specimens dripped with water from the cave epikarst into the rimstone pools.

Description. Male (holotype). Body unpigmented, nauplius eye absent. Total body length, measured from tip of rostrum to posterior margin of caudal rami (excluding caudal setae) from 280 to 315 µm, mean 301 m (n = 5). Habitus ( Fig. 2A ) cylindrical and slender, without any demarcation between prosome and urosome; prosome to urosome ratio: 0.75. Free pedigerous somites without any lateral or dorsal expansions, all connected by welldeveloped arthrodial membranes. Integument weakly sclerotized, without cuticular pits, ornamented with sensilla on all somites except preanal one; second and fourth free pedigerous somites and second urosomite with proximal dorsal pore. Cuticular windows on urosomites not present ( Fig. 2A ). Cephalothorax ( Fig. 2A ) representing about 19.3 % of total body length (measured from tip of rostrum to end of caudal ramus), cephalosome with dorsal cuticular window and medial pore. Anal somite ( Figs. 3A, B ) with pair of large dorsal sensilla at base of anal operculum, pair of cuticular ventral pores (one pore on each side) near the insertion of caudal rami. Anal operculum ( Figs. 3A, B ) well-developed, with straight distal margin. Anal sinus wide open, with spinular rows. Spermatophore as in Fig. 12A .

Caudal rami ( Figs. 3A, B ): shorter than anal somite, approximately cylindrical, slightly divergent; length/width ratio: 3.5, with distal pore between setae IV and V. Anterolateral accessory seta (I), and posterolateral seta (III) subequal in length, anterolateral seta (II) longer than seta I and III (length seta/length caudal ramus: 0.34), all three setae inserted together distally at 3/4 length of the caudal ramus. Outer terminal seta (IV) short and pinnate (length seta/length caudal ramus: 0.53); inner terminal seta (V) without fracture plane. Terminal accessory seta (VI) short (length seta/length caudal ramus: 0.40) and smooth. Dorsal seta (VII) articulate, inserted distally at 3/4 length of the caudal ramus as setae I-III.

Rostrum ( Fig. 3C ): small, almost reaching distal margin of first antennulary segment, ornamented with two dorsal sensilla.

Antennule ( Fig. 3C ): prehensile, eight-segmented pocket-knife type sensu Schminke (2010). First segment short with transversal row of spinules, second segment longest, with six setae, the longest seta plumose. Third segment with four distal bare setae; fourth segment reduced to a small sclerite with two short setae. Fifth segment enlarged, distal tubercle with two equal setae and one large aesthetasc, reaching almost to the end of eighth segment, one short seta inserted at base of tubercle; a cylindrical protrusion at the base of tubercle, carrying a spear-like spiniform seta (marked with asterisk in Fig. 3D ). Sixth segment bare, partially fused to previous one. Seventh segment bare, distal anterior corner protruding as a triangular, pointed apophysis. Eighth segment with seven setae and apical acrothek represented by two subequal setae and a slender shorter aesthetasc, approximately as long as segment. Armature formula: 1-[0], 2-[1 uniplumose + 5 bare], 3-[4 bare], 4-[2 bare], 5-[3+ 1tr +ae], 6- [0], 7-[0], 8-[7 bare + (2 + ae)].

Antenna ( Fig. 3E ): coxa unarmed; allobasis with transverse row of spinules on inner margin. Exopod represented by a small segment merged with allobasis, with pinnate apical seta. Endopod bearing two short subdistal, and five longer distal elements, two of them geniculate, all elements with long spinules near their insertions.

Labrum ( Fig. 3F ): large and approximately rectangular, with convex and smooth anterior surface, cutting edge with apical row of slender denticles.

Mandible ( Fig. 3G ): coxal gnathobase bare, cutting edge with apical teeth. One-segmented palp, with two distal setae of equal length.

Maxillule ( Fig. 3H ): praecoxal arthrite with three apical curved robust spines apically denticled, one large spine, one subdistal curved seta. Coxal endite long, with one apical seta. Basis cylindrical, with three distal bare setae of subequal length. Endopod and exopod absent (fused to basis without trace).

Maxilla ( Fig. 3I ): syncoxa with two endites, proximal endite short, with one thin seta; distal endite cylindrical, longer, armed apically with two subequal thin bare setae; allobasis prolonged into apical pinnate claw; endopod represented by small segment fused at the base, with two long setae of equal length.

Maxilliped ( Fig. 3J ): prehensile. Syncoxa small and unarmed; basis slim and elongate, unarmed; endopod represented by distally unipinnate claw.

P1 ( Fig. 3K ): with smooth and small intercoxal sclerite; basis large, armed with single slender seta on outer margin and a hook with rounded tip on the inner margin of basis; ornamented with transverse row of minute spinules at base of outer seta. Exopod three-segmented, slightly shorter than endopod, second segment shortest; exp-1 with thin and slightly curved pinnate seta on outer distal corner; exp-3 with two geniculate and one normal pinnate apical setae, and one subapical pinnate seta. Endopod two-segmented; enp-1 as long as the first two segments of the corresponding exopod, with two transversal rows of spinules on the outer margin, one spinule at 2/ 3 of the inner margin. Enp-2 thinner and shorter than enp-1, with three spinules at 2/3 of the inner margin; long, geniculate pinnate seta, and shorter pinnate seta on apex.

P2 ( Fig. 3L ): with smooth intercoxal sclerite, twice as wide as tall. Basis unarmed, with row of four spinules on outer margin. Exopod three-segmented, exp-1 longest, with transversal row of three spinules at 1/3 of outer margin, longitudinal row of three spinules proximal to strong distolateral pinnate spine, row of four smaller spinules along outer distal margin; second and third segments of same length, exp-3 armed with subapical outer unipinnate spine, apical bipinnate seta and unipinnate spine. Endopod one-segmented, about 1/3 the length of the corresponding exp- 1, represented by cylindrical segment, with apical seta about as long as segment.

P3 ( Figs. 3M, N ): intercoxal sclerite narrow and tall, trapezoidal, unornamented, with slightly concave distal margin. Coxa with distal spinule row. Basis robust, with long, slender, smooth outer seta, basal pore and transverse spinule row above outer seta, inner row of transversal spinules. Endopod reduced to short seta. Exp-1 of characteristic shape, enlarged near origin of distal apophysis; inner margin with thin and long conical proximal tubercle fused to exopod. Exp-2 fused with exp-1, without ornamentation, prolonged into long apophysis slightly bent inwards, with pointed tip. Distal thumb represented by thin and pointed segment, reaching to 1/2 of the apophysis.

P4 ( Figs. 4A, B ): intercoxal sclerite smaller than in P1 or P2, with concave, smooth distal margin. Basis armed with single slender seta on outer margin; ornamented with row of spinules at base of outer seta; two spiniform processes of different size, slightly curved inwards aligned along inner margin, the larger one close to endopod. Exopod three-segmented, slender, all segments approximately of the same length; exp-1 slightly curved inwards, with distolateral pinnate spine; exp-3 armed with outer pinnate spine and very long apical pinnate seta, spine length less than 1/3 of seta length. Endopod one-segmented, length about 1/2 than corresponding exp-1, represented by a cylindrical element distally enlarged in three pointed protrusions, the middle one strongest and apically curved outwards.

P5 ( Fig. 4D ): fused to intercoxal sclerite, represented by two trapezoidal cuticular plates with inner-distal corner produced into small pointed tip, one large pore at midlength of each plate. Armature on free distal margin, from inner to outer: three bare setae of different length, innermost shortest, middle one longest, and long basipodal seta.

P6 ( Fig. 4D ): vestigial, fused into simple cuticular plate, unornamented and unarmed.

Female. Body length, excluding caudal setae, from 260 to 315 m, mean 289 m (n = 5), ornamentation of cephalothorax ( Fig. 11A ), somites, pigmentation, and lack of nauplius eye as in male, except genital and first urosomite fused into double-somite. Prosome/urosome ratio: 0.86. Genital double-somite (Fig. 5F) without any trace of subdivision. Genital field (Figs. 5F, 12A) broader than tall, occupying anterior ventral half of genital double-somite; single genital aperture covered by fused vestigial sixth legs; median copulatory pore located medially at 1/3 of double-somite length. Anal operculum and anal sinus as in male.

Caudal rami ( Fig. 4E, F , 12B ): shape, ornamentation and armature similar to those of male, length/width ratio: 3.5.

Rostrum, antenna, oral appendages, maxilliped, as in male.

Antennule ( Figs. 4G , 11A ): seven-segmented, aesthetasc on fourth segment longer and thinner than in male, reaching below end of seventh segment. First segment bare. Second segment longest. Apical acrothek represented by two setae of different length and slender aesthetasc. Armature formula: 1-[0], 2-[1 pinnate +3 bare], 3-[4 bare], 4-[2 + ae], 5-[0], 6-[0], 7-[6 bare + (2 + ae)].

FIGURE 5. Stammericaris destillans sp. nov., female: A, P1 basis, detail; B, P2; C, P3; D, P4; E, P5; F, first urosomite, P5, genital double-somite and genital field, P6, ventral view. Scale bar: 50 micrometers.

P1 (Figs. 5A, 11B): basis, ornamentation and armature as in male except with inner curved seta apically transformed instead than hook ( Fig. 11B ); exopod and endopod similar to the male’s ones in shape, ornamentation and armature.

P2 (Figs. 5B, 11C): intercoxal sclerite longer and narrower than in male, basis as in male but with spinular row below endopod insertion ( Fig. 11C ). Exp-1 less inwardly curved than in male, and subapical outer spine inserted more distally; remaining ornamentation and armature of exopod as in male. Endopod similar in shape and ornamentation to that of the male, but proportionally slightly longer.

P3 (Figs. 5C, 11D): intercoxal sclerite small, with concave margin, bare. Basis with outer seta and spinular row and pore near seta insertion, spinular row below endopod insertion; exopod two-segmented: exp-1 slightly shorter than exp-2, with distolateral pinnate spine and transversal row of four spinules at 1/2 of the outer margin; exp-2 with subapical outer pinnate spine and apical pinnate seta, spine slightly longer than 1/3 of seta. Endopod represented by a thin and pointed segment, slightly longer than half of corresponding exp-1, (at about 4500x magnification (SEM) apically pinnate).

P4 (Figs. 5D, 11E, 12A): intercoxal sclerite, basis as in male, with pore near outer seta insertion; exopod as in male. Endopod with spinular row near insertion, represented by a thin cylindrical segment, about the length of corresponding exp-1, ending in a short pinnate seta fused with endopod, with four spinules near insertion.

P5 (Figs. 5E, F, 11F, 12A): fused to intercoxal sclerite, represented by two cuticular plates slightly longer than in the male, with inner-distal corner produced into long and strong pointed tip, one large pore at midlength of each plate. Armature on free distal margin, from inner to outer: two bare setae of same length, one very small seta, and long basipodal seta.

P6 (Fig. 5F): vestigial, fused into simple cuticular plate, covering gonopore, unornamented and unarmed.

Variability. Three female paratypes with seta V of caudal rami proximally enlarged. In one male paratype the spiniform process on P4 basis closest to the endopod is smaller than the far most one ( Fig. 4C ).

Figures

FIGURE 2. A, Stammericaris destillans sp. nov.: A, male, habitus, lateral view; B, Stammericaris trinacriae (Pesce, Galassi and Cottarelli, 1988), male, habitus, lateral view. Scale bar: 50 micrometers.

FIGURE 3. Stammericaris destillans sp. nov., male: A, anal somite, anal operculum and caudal rami, dorsal view; B, anal somite, anal operculum and caudal rami, ventral view; C, rostrum and antennule, dorsal view; D, fifth antennular segment, ventral view; E, antenna; F, labrum; G, mandible; H, maxillule; I, maxilla; J, maxilliped; K, P 1; L, P 2; M, P 3; N, P 3, outer view. Scale bar: 50 micrometers.

FIGURE 4. Stammericaris destillans sp. nov.: A, male, P 4, dorsal view; B, male, P 4 basis and endopodite, lateral view; C, male, P 4 basis and endopodite, lateral view, variability; D, male, P 5, P 6, first to third urosomites, ventral view; E, female, anal somite, anal operculum and caudal ramus, lateral view; F, female, anal somite, anal operculum and caudal ramus, ventral view; G, female, antennule. Scale bar: 50 micrometers.

FIGURE 11. Stammericaris destillans sp. nov., female: A, antennule, cephalothorax and first pedigerous somite, dorsal view; B, P 1 basis, inner view; C, P 2 basis and endopod, inner view; D, P 3 basis and endopod, anterior view; E, P 4 basis and endopod, inner view. F, P 5.

FIGURE 12. Stammericaris destillans sp. nov.: A, female, P 4, P 5, genital field with attached spermatophore, ventral view; B, female, caudal ramus, outer view. Stammericaris trinacriae (Pesce, Galassi and Cottarelli 1988), male: C, habitus, lateral view; D, cephalothorax and first two pedigerous somites, antennule, antenna, P 1, P 2, lateral view. E, basis P 1, inner view; F, P 3, inner view.