Proserpinicaris specincola Bruno & Cottarelli, 2020

Bruno, Maria Cristina, Cottarelli, Vezio, Marrone, Federico, Grasso, Rosario, Stefani, Erika, Vecchioni, Luca & Spena, Maria Teresa, 2020, Morphological and molecular characterization of three new Parastenocarididae (Copepoda: Harpacticoida) from caves in Southern Italy, European Journal of Taxonomy 689, pp. 1-46 : 27-34

Proserpinicaris specincola Bruno & Cottarelli sp. nov.

urn:lsid:zoobank.org:act:7368747C-5CFB-4AF0-86E2-69860DF7E985

Figs 12 b–j, 13–14; Table 1

Diagnosis

Proserpinicaris specincola Bruno & Cottarelli sp. nov. is characterized by the morphology of P 3 in the males: the inner margin of exp-1 is straight, without a beak and/or one or more chitinous lobes; exp-2 is prolonged into a finger-like apophysis. The basis P4 of males has a long and pointed process, as long as exp-1, inserted between enp and exp. Both sexes are characterized by the reduced size, a thin cuticle and the lack of integumental windows on the urosomites and the cephalothorax, and the apical seta on P2 enp are missing.

Etymology

The species epithet is the genitive singular of the Latin word ‘ specus ’, meaning ‘cave’ and the nominative ‘ incola ’, meaning ‘inhabitant’, underlining that this species is a cave-dweller.

Material examined

Holotype

ITALY • ♂; Crotone Province, Verzino, Complesso Le Grave , Grave Grubbo , pool 2; approximate coordinates 39°15′41.4ʺ N, 16°51′45.1ʺ E; 28 Aug. 2015; R. Grasso and M.T. Spena leg.; dissected and mounted on one slide labelled “ Proserpinicaris specincola holotype: male”; NHMUK 2020.41 .

Paratypes

ITALY • 1 ♂; same collection data as for holotype, pool 3; 21 Apr. 2018; dissected and mounted on one slide labelled “ Proserpinicaris specincola paratype: male”; NHMUK 2020.42 • 1 ♀, same collection data as for holotype; mounted on one slide labelled “ Proserpinicaris specincola paratype: female”;

NHMUK 2020.43 • 1 ♀, same collection data as for holotype; dissected and mounted on one slide labelled “ Proserpinicaris specincola paratype: female”; NHMUK 2020.44 .

Description

Adult male

BODY. Unpigmented, nauplius eye absent. Total body length, measured from tip of rostrum to posterior margin of caudal rami (excluding caudal setae) from 372 to 384 µm, mean 363 μm (n = 2). Habitus cylindrical and slender, without any demarcation between prosome and urosome; prosome to urosome ratio: 0.90. 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. Cuticular windows on urosomites and cephalothorax not observed. Cephalothorax representing about 15 % of total body length. Anal somite ( Fig. 12b, j ) with pair of large dorsal sensilla at base of anal operculum. Anal operculum ( Fig. 12b, j ) well developed, with straight distal margin. Anal sinus wide open. Spermatophore as in Fig. 12c .

CAUDAL RAMI ( Fig. 12b, j ). Shorter than anal somite, approximately cylindrical, length to width ratio: 3. Anterolateral accessory seta (I) and anterolateral seta (III) long and subequal in length, smooth; posterolateral seta missing, all setae inserted together proximally at ¼ length of caudal ramus. Outer terminal seta (IV) long and unipinnate (length seta/length caudal ramus: 1.3), inserted subterminally; inner terminal seta (V) without fracture plane. Terminal accessory seta (VI) short (length seta/length caudal ramus: 0.9) and smooth. Dorsal seta (VII) articulate, inserted distally at ¾ length of caudal ramus.

ROSTRUM ( Fig. 12d ). Small, not demarcated at base, almost reaching distal margin of A1, ornamented with two dorsal sensilla.

A1 ( Fig. 12d ). Prehensile, eight-segmented coiled type sensu Schminke (2010). First segment short, second segment longest, with six setae, longest seta unipinnate. Third segment with four distal bare setae; fourth segment reduced to small bare sclerite. Fifth segment enlarged, with lateral seta and distal tubercle with two long subequal setae and one short aesthetasc. Sixth segment bare, partially fused to previous one. Seventh segment bare. Eighth segment with seven setae and apical acrothek represented by two seta and short aesthetasc. Armature formula: 1-[0], 2-[1 uniplumose + 5 bare], 3-[4 bare], 4-[0], 5-[3 bare + ae], 6-[0], 7-[0], 8-[7 bare + (2 + ae)].

A2 ( Fig. 12e ). Coxa unarmed; allobasis with one transverse row of four spinules on inner margin. Exp represented by small segment merged with allobasis, with pinnate apical seta. Enp bearing three proximal spinules and two unipinnate spines along inner margin, one transformed seta subapically on outer margin; one spine, two geniculate and one normal setae, all unipinnate, on the distal margin.

MDB ( Fig. 12f ). Coxal gnathobase with lateral pinnate short seta, cutting edge with apical teeth. Onesegmented palp, with two distal setae of subequal length.

MX 1 ( Fig. 12g ). Praecoxal arthrite with three apical curved robust spines apically denticled, one subdistal curved seta. Coxal endite long, with one apical seta. Basis cylindrical, with three distal bare setae. Enp and exp absent (fused to basis without trace).

MX 2 ( Fig. 12h ). Basis with two endites, proximal endite short, with one thin, bare seta; distal endite cylindrical, longer, with two bare and one leaf-like seta; proximal endopodal segment drawn into apical unipinnate claw; distal endopodal segment small, with two long setae of equal length.

MXP ( Fig. 12i ). Subchelate, composed of small and unarmed syncoxa, basis slim and elongate, unarmed, 1-segmented enp fused to the claw-like apical seta.

P1 ( Fig. 13a ). With smooth and small intercoxal sclerite; coxa large and bare. Basis large, armed with single slender seta on outer margin. Exp three-segmented, slightly longer than enp, exp-1 with thin spiniform seta on outer distal corner; exp-2 shortest and unarmed; exp-3 with two geniculate and one normal apical unipinnate setae and one unipinnate subapical seta. Enp two-segmented; enp-1 as long as first two segments of the corresponding exp, with two transversal rows of spinules on outer margin, longitudinal row of spinules at ¼ of inner margin. Enp-2 thinner and shorter than enp-1, with three spinules at ¼ of inner margin and four at ¼ of outer margin; with long, geniculate seta and shorter unipinnate seta on apex.

P2 ( Fig. 13b ). With smooth and small intercoxal sclerite, three times as wide as long; coxa bare. Basis unarmed, with row of four spinules on outer margin; one proximal transversal row of spinules and another transversal row between enp and exp. Exp three-segmented, exp-1 longest, with two transversal rows of spinules, transversal row of spinules proximal to strong distolateral bipinnate spine, hyaline frill on inner distal corner. Second and third segments of same length; exp-2 unarmed, with row of spinules on distolateral corner, hyaline frill on distal inner corner; exp-3 armed with subapical outer unipinnate spine, apical bipinnate seta and unipinnate spine, and inner hyaline frill. Enp one-segmented, about half length of corresponding exp-1, cylindrical, with small outer spinule inserted at half-length and two short apical spinules.

P3 ( Fig. 13c ). Intercoxal sclerite narrow and tall, trapezoidal, unornamented, with slightly concave distal margin. Coxa bare. Basis robust, with long, slender, smooth outer seta, one transverse spinule row above and one row of small, elongate lamellae inserted subdistally and transversally on ventral surface. Enp reduced to short, bare seta. Exp-1 rectangular, outer margin without ornamentation, inner margin straight, without buldges; exp-2 fused with exp-1, without ornamentation, prolonged into short fingerlike apophysis with round tip and apical short spine. Distal thumb represented by leaf-like segment, longer than apophysis.

P4 ( Fig. 13d ). Intercoxal sclerite smaller than in P1 or P2, with concave, smooth distal margin; coxa bare. Basis armed with single slender seta on outer margin; ornamented with row of spinules on outer margin; with long and pointed process, as long as exp-1, inserted between enp and exp. Exp threesegmented, slender, all segments approximately of same length but progressively thinner; exp-1 slightly curved inwards, with distolateral bipinnate spine; proximal group of three spinule and distal group of two spinules on outer margin, longitudinal row of four long setules distally along inner margin and distal spinular row; exp-2 unarmed, with distal spinular row; exp-3 armed with apical unipinnate spine and long apical unipinnate seta, spine length less than ¼ of seta length, ornamented with distal spinular row and inner hyaline frill. Enp one-segmented, as long as first segment of corresponding exp, spiniform, pointing inwards and crenulated in proximal half, smooth in distal half, ending in tip.

P5 ( Fig. 13e ). Fused to intercoxal sclerite; represented by triangular cuticular plate, inner distal corner produced into very large spiniform process, ornamented with short row of three spinules along inner margin and cuticular pore on anterior surface, armed with long basipodal seta and two bare setae of subequal length.

P6 ( Fig. 13e ). Vestigial, fused into simple cuticular plate, unornamented and unarmed.

Adult female

HABITUS. Cylindrical and slender, without any demarcation between prosome and urosome. Free pedigerous somites without any lateral or dorsal expansions, all connected by well-developed arthrodial membranes. Integument weakly sclerotized, without cuticular pits, ornamented with sensilla on all somites except preanal one. Cuticular windows on urosomites and cephalothorax not present. Body length, excluding caudal setae, from 355 to 376 μm, mean 363 μm (n = 2), ornamentation of cephalothorax, somites, pigmentation, and absence of nauplius eye as in male, except genital and first urosomite fused into double-somite. Cephalotorax representing about 16% of total body length. Prosome/urosome ratio: 0.90. Genital double-somite ( Fig. 14j ) without any trace of subdivision, with pair of ventral cuticular pores. Genital field as in Fig. 14j . Anal somite with pair of lateral basal pores ( Fig. 13f ). Anal operculum and anal sinus as in male.

CAUDAL RAMI ( Fig. 13f ). Shape, ornamentation and armature similar to those of male, length to width ratio: 2.6

ROSTRUM, A2, ORAL APPENDAGES AND P1. As in male.

A1 ( Fig. 14a ). Seven-segmented, aesthetasc on fourth segment shorter than in male, reaching below end of seventh segment. First segment bare, second segment longest. Apical acrothek represented by two setae of subequal length and slender aesthetasc. Armature formula: 1-[0], 2-[1 unipinnate + 3 bare], 3-[4 bare], 4-[2 bare + ae], 5-[0], 6-[0], 7-[7 bare + (2 bare + ae)].

P2 ( Fig. 14 b–c). Basis and exp as in male. Enp similar in shape and ornamentation to that of the male, but apical spinules longer.

P3 ( Fig. 14 d–e). Intercoxal sclerite small, with concave margin, bare. Coxa bare. Basis with outer seta and spinular row near seta insertion. Exp two-segmented: exp-1 longer than exp-2, with subdistal unipinnate spine and transversal row of three and two spinules at ¼ and ¼ of outer margin, hyaline frill on inner distal corner; exp-2 with apical outer unipinnate spine and apical bipinnate seta, spine length about ½ of seta, hyaline frill on inner distal corner. Enp represented by thin cylindrical segment, slightly shorter than ¼ of exp-1, with apical row of short spinules.

P4 ( Fig. 14 f–h). Intercoxal sclerite, coxa and exp as in male. Basis without long spinule between insertion of exp and enp. Enp represented by pointed cylindrical segment, slightly longer than exp-1, with two spinules inserted at ¼ of margin.

P5 ( Fig. 14 i–j). Fused to intercoxal sclerite, represented by cuticular plate, more elongated than in male, without basal pore and with five spinules inserted at about 4/5 on inner margin; armed with long basipodal seta and two bare setae of subequal length.

P6 ( Fig. 14j ). Vestigial, fused into simple cuticular plate, covering gonopore, unornamented and unarmed.

Accompanying fauna

Grave Grubbo, 28 Aug. 2015: Nitocrella stammeri Chappuis, 1938 : pool 3, pool 8, pool 11; Speocyclops sp.: pool 6, pool 8; Bryocamptus sp.: pool 6; Attheyella crassa (G.O. Sars, 1863) : pool 9.

Molecular phylogenetic analysis

Overall, 38 harpacticoids specimens, 34 of which belonging to the family Parastenocarididae , were analysed and included in the analyses ( Table 2). After trimming out the tails of the sequences, which were not present in all the individuals, we obtained a properly aligned 2090 bp-long combined fragment. The COI and 18S sequences produced in the frame of present work were deposited in GenBank ( Table 2). The BI and ML trees based on the combined dataset and rooted on Bryocamptus stillae show a congruent topology, in agreement with the current morphology-based taxonomy, with a wellsupported parastenocaridiid clade ( Fig. 15 ). Within the analysed Parastenocarididae , a first dichotomy separates Proserpinicaris amalasuntae from a clade including, with a sister-taxa relationship, the Parastenocaridinae Cottarellicaris sanctiangeli Bruno & Cottarelli sp. nov. and Stammericaris spp. Interestingly, specimens of Cottarellicaris sanctiangeli sp. nov. from Vucco Ucciardo and Grotta superiore di Sant’Angelo shared a unique haplotype, whereas a different haplotype occured in specimens

of C. sanctiangeli sp. nov. collected in Grotta del Banco di ferro. Conversely, two haplotypes were observed in specimens of Stammericaris vincentimariae Bruno & Cottarelli sp. nov. from Grotta dello Scoglio, constituting a well-supported clade with sister-clade relationship with S. pasquinii ( Fig. 15 ).

Based on the COI dataset, pairwise distances ( Table 3) between S. vincentimariae Bruno & Cottarelli sp. nov. and the other species of Stammericaris ranged between 12.9% ( S. pasquinii ) and 24.9% ( S. diversitatis ); the distances between Cottarellicaris sanctiangeli Bruno & Cottarelli sp. nov. and all the species of Stammericaris ranged between 22.4% ( S. diversitatis ) and 25.9% ( S. vincentimariae sp. nov.). Species belonging to different subfamilies were most distant (i.e., 32% pairwise distance for P. amalasuntae vs S. pasquinii ).

Figures

Fig. 12. a. Stammericaris vincentimariae Bruno & Cottarelli sp. nov., ♀ (NHMUK), first urosomite, P5, P6, genital double-somite and genital field, ventral view. — b–j. Proserpinicaris specincola Bruno & Cottarelli sp. nov., ♂ (NHMUK). b. Anal somite, anal operculum and caudal rami, dorsal view. c. Spermatophore. d. Rostrum and A1, disarticulated (antennular segments marked with roman numerals). e. A2. f. Mdb. g. Mx1. h. Mx2. i. Mxp. j. Anal somite, anal operculum and caudal rami, lateral view. Scale bar: 50 µm.

Fig. 13. Proserpinicaris specincola Bruno & Cottarelli sp. nov. (NHMUK). a. ♂, P1, posterior view. b. ♂, P2, posterior view. c. ♂, P3, posterior view. d. ♂, P4, anterior view. e. ♂, P5, P6, first and second urosomites, ventral view. f. ♀, anal somite, anal operculum and caudal rami, lateral view. Scale bar: 50 micrometers.

Fig. 14. Proserpinicaris specincola Bruno & Cottarelli sp. nov., ♀ (NHMUK). a. Rostrum and A1. b. P2 coxa, basis and exp, outer view. c. P2, enp. d. P3, basis and exp, outer view. e. P3, enp. f. P4, basis and exp, outer view. g. P4, enp. h. P4 coxa, basis and first exopodal segment, and enp, inner view. i. P5. j. P5, P6, genital double-somite and genital field, ventral view. Scale bar: 50 µm.

Fig. 15 (opposite page). Bayesian phylogram (95% majority rule consensus tree) of the investigated Parastenocarididae Chappuis, 1940 based on the 2090 bp fragment of the combined dataset including COI and 18S sequences. Bryocamptus (Rheocamptus) stillae Cottarelli & Bruno, 2012 and Bereraia sp. used as outgroups to root the tree. Node statistical support is reported as nodal posterior probabilities (Bayesian Inference of phylogeny, BI) / bootstrap values (Maximum Likelihood, ML). Asterisks indicate a bootstrap support value lower than 50.