Research Article |
Corresponding author: Andrés G. Morales-Núñez ( amoralesnunez@yahoo.es ) Academic editor: Martin Husemann
© 2017 Andrés G. Morales-Núñez, Sterling Ulrich, Richard W. Heard.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Morales Núñez AG, Ulrich S, Heard RW (2017) Brachylicoa lui, a new species of Tanaidacea (Crustacea: Peracarida: Parapseudidae), from the Hawaiian Islands, with a taxonomic key. Zoosystematics and Evolution 93(2): 1-23. https://doi.org/10.3897/zse.93.13824
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Brachylicoa lui sp. n. is described from the coastal waters of the Hawaiian island of O‘ahu. It is distinguished from the other four nominal members of Brachylicoa by a combination of characters including (1) an incised margin between base of rostrum and carapace, (2) mandible palp article-1 with cluster of 20–25 simple setae, (3) maxillule biarticulate palp ending in eight “cleaning’ setae, (4) maxilliped inner sub-distal margin with two stout spiniform seta, and (5) pereopod-6 with carpus having three plumose setae on mid-dorsal margin. Brachylicoa (=Apseudes) babelmandebensissensu Guţu is tentatively transferred to the genus Saltipedis Guţu sensu lato. Brachylicoa lui is the only member of the genus known from the mid-Pacific Region and the Northern Hemisphere; the other species of the genus are known from the western Pacific and Indian Ocean in the Southern Hemisphere. A key to separate the four nominal species of Brachylicoa species is presented.
Brachylicoa lui sp. n. Parapseudidae, O‘ahu, Mid-Pacific Region, taxonomy
An examination of the Tanaidacea holdings of the Bernice Pauahi Bishop Museum, Honolulu, Hawai‘i (BPBM) in 2015, revealed the presence of an apparently undescribed species belonging to the parapseudid genus Brachylicoa Guţu, 2006.
The description of the new Hawaiian species of Brachylicoa is the subject of this paper and represents the fourth in a series of publications dealing with the Tanaidacea of these mid-Pacific islands mentioned above.
The material examined during this study came from the Bernice Pauahi Bishop Museum (BPBM), Honolulu, Hawai‘i (BPBM), the Bohart Museum of Entomology (BME), University of California at Davis, and a collection made by the authors. Specimens from BPBM came from material collected from three coastal sites; (1) an ocean-water settling chamber in 1978 located at a now abandoned Naval Experimental site on the oceanic side of Mokapu Peninsula (type locality), (2) Kāne‘ohe Bay (adjacent to the type locality), and (3) Waikīkī. Material from the type locality was scraped by hand from sediment collection trays. Specimens from Kāne‘ohe Bay and Waikīkī were collected with sediment cores (12.5 cm diameter by 15 cm deep) pushed into the substratum and sieved through a 0.5 mm mesh screen (Coles et al. 2002 a, b). Material collected by the authors came from Makupu‘u Tidepools and was collected by “rock washings”. The late M. A. Miller collected the specimens from BME by hand from Coconut Island Reef, Kāne‘ohe Bay.
Other material (“Brachylicoa cf. lui”) from the eastern Hawaiian Islands [i.e., Hawai‘i (Big Island), Moloka‘i, and Maui] was collected by the same methods used for Kāne‘ohe Bay and Waikīkī studies (see Cole et al. 2004).
All the material was initially preserved in 10% formalin and then stored in ethanol. Specimens were dissected under an Olympus ZS-16 stereomicroscope. Appendages were mounted on glass slides in glycerin and observed with an Olympus BX41 microscope, and drawings were made with a camera lucida. Illustrations were prepared with Adobe Illustrator CC 2017. Photographs were taken using an Olympus DP73 digital camera mounted on a stereomicroscope and/or compound microscope and all specimens were measured with CellSens Dimension 1.11 Imaging Software (Olympus). Map was created using ArcGIS 10.4.1 software (University of Maryland Eastern Shore (UMES)).
The total lengths for all specimens in the type series of the new species of Brachylicoa were measured. Notwithstanding the presence on pereonite-6 of a male genital cone, hermaphroditic specimens having oostegites (marsupia) or oostegite buds are considered functional females. The various stages or forms observed were placed into six categories: (1) subadult <3.5 mm TL without distinctive secondary characters (e.g. oostegites and genital cone 6), (2) adult females with oostegites and genital cone, (3) adult ovigerous females and genital cone, (4) adult females with marsupium, (5) adult females with marsupium and genital cone, and (6) adult males having a genital cone with no indication of oostegites.
Type material is deposited in the Bernice Pauahi Bishop Museum, Honolulu, Hawai‘i (BPBM); National Museum of Natural History, Smithsonian Institution, Washington, DC (USNM); and Gulf Coast Research Laboratory Museum (GCRL). All measurements are in millimeters (mm). Total body length (TL) is measured from the tip of the rostrum to the tip of the pleotelson. Terminology used in this description generally follows that of
BPBM: Bernice Pauahi Bishop Museum, Honolulu, Hawai‘i; BME: Bohart Museum of Entomology, University of California at Davis; USNM: National Museum of Natural History, Smithsonian Institution, Washington DC; GCRL: Gulf Coast Research Laboratory Museum; TL: Total body length; Stn: Station
See
Hermaphroditism common with many adults having both oostegites and male genital cone. Rostrum weakly incised or entire at interface with carapace, broad posteriorly and with lateral margins entire or serrate, becoming greatly compressed anteriorly to form small, narrow, acute tip. Carapace ventral margins with row of 9−13 spiniform setae. Pereonite-6 and pleonites 1−5 lacking transverse row of setae on dorsal surface. Antennule with peduncle article-1 having 2−3 distinctive spiniform setae on inner margin and with flagella nearly equal in length. Ventral margins of carapace with row of 9−13 spiniform setae. Maxilliped basis with one or two, spiniform, stout seta on or near inner distal margin. Pereopod-1 with length of basis about equal to combined lengths of ischium-merus-carpus; merus with spiniform setae on distoventral margin; carpus with spiniform seta on distodorsal and distoventral margins; propodus having distodorsal margin with large spiniform seta (immediately adjacent to dactylus) and ventral margin with two to four spiniform setae. Pereopod-4 with propodus having sub-distal crown of setulate spiniform, lanceolate setae. Pereopod-6 having basis with long setae (plumose and/or simple) on dorsal and ventral margins; propodus with oblique semi-circle of setulate spiniform, lanceolate setae distally.
Male. Cheliped robust, with dorsal margin of basis armed small, but distinct spinose process.
Brachylicoa muelleri (Guţu, 1998)
Composition (four species). Brachylicoa estasiatica Guţu, 2007; B. indonesiana Guţu, 2006; B. lui sp. n. (see below); B. muelleri (Guţu, 1998).
Remarks. Based on our observations, we conclude that the questionable species “B. babelmandebensis” (Băcescu, 1978) described from the North west Indian Ocean, is not congeneric with Brachylicoasensu stricto. It is immediately distinguished from the other nominal members of Brachylicoa by a having an acutely tipped rostrum with a unique pair of anteriorly directed, lateral spines and by the first pleonite having a distinct transverse, dorsal row of small setae near its anterior margin (see
Although not prominent, we consider another reliable generic character, originally noted by
Holotype. Ovigerous hermaphrodite with male genital cone (BPBM S17058), TL 8.3 mm, Station (Stn) Ulupau (Head), Tray10, (780041HI − jar #23102, labelled as Apseudes sp. #2), (21°27'24.26"N, 157°44'10.29"W), from Naval Experimental site (no longer extant), Mokapu Peninsula, O‘ahu, Hawai‘i, 05-Dec-1978.
Paratypes. Same collection data as for holotype. One ♀ with marsupium and genital cone (BPBM S17059), TL 7.56 mm; one ♂ without oostegites but with genital cone (BPBM S17060), TL 8.4 mm; one ♀ with marsupium (USNM 1422411), TL 8.8 mm; one ♀ with marsupium and genital cone, TL 6.47 mm (USNM 1422412); one ♀ with eggs and genital cone (USNM 1422413), TL 7.5 mm; one ♀ with oostegites and genital cone, TL 6.83 mm (GCRL 06586); one ♀ with eggs and genital cone, TL 6.80 mm; (GCRL 06587). Additional specimens from the type locality are in the collection of the Bernice Pauahi Bishop Museum, Honolulu, Hawai‘i (BPBM).
Same collection data as for holotype. One subadult, TL 3.03 mm; one ♀with oostegites and genital cone, TL 5.15 mm; one ♀ with oostegites and genital cone, TL 6.02 mm. Additional specimens from the type locality are in the collection of the authors.
Kāne‘ohe Bay, O‘ahu (collectors:
Kāne‘ohe Bay, O‘ahu (BME). — Four ♂, six ♀♀ (ovigerous), (21°26'38"N, 157°47'47"W), Coconut Island Reef, lee side, coll. by M.A. Miller [Miller accession No. 2642]. 15 August 1961.
Waikīkī, O‘ahu (Collectors:
Makupu‘u Tidepools, O‘ahu. — One manca, two subadults, (21°19'0.95"N, 157°39'52.13"W), depth 0-1 m, coll. by Andrés G. Morales-Núñez and Richard W. Heard, 22 Oct 2015
(
Diagnosis. Often hermaphroditic, having both four pairs of oostegites and male penal cone mid-ventrally on pereonite-6. Rostrum weakly incised at base, with slightly rounded, non-serrate shoulders, becoming immediately constricted distally to form, short, acute tip. Left mandible with lacinia mobilis having five denticles (proximal being most minute). Mandibular palp with article-1 having cluster of 20−25 simple setae. Pereopod-1 with propodus having ventral margin bearing two, rarely three, stout spiniform setae. Pereopod-6 with basis having row of plumose setae on dorsal and ventral margins; carpus with row of three plumose setae on mid-dorsal margin. Cheliped on both sexes and on hermaphroditic forms with exopod bearing five terminal plumose setae.
Female. Cheliped exhibiting two forms; first form typical of parapseudid females, having narrow carpus length three to four times width and chela lacking teeth; second form robust and similar to male cheliped, but with dorsal margin of basis lacking blunt spinose process.
Male. Cheliped robust, with dorsal margin of basis armed small, but distinct spinose process; carpus massive, length about twice width, widest distally; fixed finger of propodus and moveable finger each with tooth.
Hermaphrodites having cheliped similar to those of male, with sub-proximal anterior margin of basis with or without blunt spinose process.
This species is named in honor of the late Lu Eldredge, a true gentleman and scholar, who contributed greatly to our understanding of the zoogeography, natural history, and marine ecology of the Pacific Ocean. Lu, also, is remembered fondly by colleagues and friends for his warm hospitality, generosity, kindness, and willingness to share his vast knowledge of the natural history and culture of the Mid and West Pacific.
Oceanic water sediment settling chamber (now closed and abandoned), Naval Experimental site (21°27'24.26"N, 157°44'10.29"W), Mokapu Peninsula (Ulupau Head), O‘ahu, Hawai‘i.
Distribution. Known with certainty from the shallow coastal waters of the O‘ahu island, Hawaiian Archipelago.
We examined similar, possibly conspecific, BPBM material of Brachylicoa from the eastern Hawaiian Islands of Hawai‘i (Big Island), Moloka‘i, and Maui. Most of the relatively few specimens available for study were damaged subadults and females. We did not include specimens from these three islands in the distribution records for B. luisensu stricto because of their relatively poor condition and geographical isolation from the O‘ahu population of B. lui. To determine if cryptic species are represented or if the specimens from the Big Island, Moloka‘i, and Maui represent a single variable species will have to resolved with certainty using molecular genetic comparisons.
Hermaphrodite adult. With oostegites present on pereonites 1−4 and pereonite-6 with genital cone.
Body (Fig.
Cephalothorax (Fig.
Pereon (Fig.
Pleon (Fig.
Pleotelson (Fig.
Antennule (Fig.
Antenna (Fig.
Mouthparts. Labrum (Fig.
Brachylicoa lui sp. n. holotype female with oostegites and genital cone. A and H right mandible; B enlargement of tip of right incisor process; C enlargement of right lacinia mobilis; D right mandible palp; E enlargement of pectinate seta; F and I left mandible; G enlargement of left lacinia mobilis; J labium. Scale bars = 0.1 mm for A, D−E, G−I.
Brachylicoa lui sp. n. holotype female with oostegites and genital cone. A maxillule; B enlargement of penta-furcate spiniform setae; C maxilla; D−F, enlargement of inner pinnate-plumose spiniform setae; G enlargement of bipinnate-outer setulose spiniform seta; H enlargement of trifurcate-plumose spiniform seta; I enlargement of outer pectinate-outer setulose spiniform seta; J enlargement of bipinnate spiniform setae K enlargement of bifid basally-swollen seta; L maxilliped; M enlargement of distal outer margin of maxilliped palp-1; N enlargement of inner-setulate spiniform seta; O endite, P apically-bidentate spiniform setae; Q enlargement of leaf-shaped bifid spiniform seta; R epignath. Scale bars = 0.1 mm for A, C, L, O, R.
Maxilliped (Fig.
Epignath (Fig.
Cheliped (Fig.
Pereopod-1 (Fig.
Brachylicoa lui sp. n. holotype female with oostegites and genital cone. A pereopod-1, lateral view; B basis of pereopod-1, inner view; C propodus and dactylus of pereopod-1, inner view; D pereopod-2, lateral view; E basis of pereopod-2, inner view; F propodus and dactylus of pereopod-2, inner view. Scale bar = 0.5 mm.
Pereopod-2 (Fig.
Pereopod-3 (Fig.
Brachylicoa lui sp. n. holotype female with oostegites and genital cone. A pereopod-3, lateral view; B basis of pereopod-3, inner view; C propodus and dactylus of pereopod-3, inner view; D pereopod-4, lateral view; E propodus and dactylus of pereopod-4, inner view; F enlargement of setulate spiniform, lanceolate setae. Scale bar = 0.5 mm for A−E.
Pereopod-4 (Fig.
Pereopod-5 (Fig.
Pereopod-6 (Fig.
Pleopods (Fig.
Uropods (Fig.
Mucus glands/storage sites (Fig.
The adult male cheliped is robust and distinctly more massive than those described for the females of other members of the genus. As in the other known males of Brachylicoa, the dorsoproximal margin of the cheliped basis of B. lui bears a relatively small, blunt spiniform process (Fig.
Brachylicoa lui exhibited some degree of variation among the individuals especially in the number of articles in uropodal exopod and endopod articles varied ontogenically, i.e., subadult and females with oostegites and genital cone have fewer articles than females with eggs/marsupium and a genital cone (7−11 versus 11−12, respectively) (Table
TL, mean ± SE, and comparison of morphological features of sexual stages of Brachylicoa lui sp. n. from the Naval experimental site.
Stages | TL (mm) | No. of uropodal exopod articles | No. of uropodal endopod articles |
---|---|---|---|
Subadult | |||
1 | 3.03 | 7 – 8 | 33 – 33 |
Adult females with oostegites and genital cone | |||
1 | 5.15 | 7 – 8 | Missing |
2 | 6.02 | 11 | 33 – 35 |
Mean ± SE | 5.59 ± 0.44 | ||
Adult ovigerous females and genital cone | |||
1 | 6.80 | 11 | 40 – 42 |
2 | 6.83 | Missing | Missing |
3 | 7.54 | 11 | 34 – 37 |
Mean ± SE | 7.06 ± 0.24 | ||
Adult females with marsupium, no indication of male cone | |||
1 | 8.82 | 12 | 43 – 45 |
Adult females with marsupium and genital cone | |||
1 | 6.47 | 11 | 36 – 38 |
2 | 7.56 | 12 | 44 – 47 |
3 | 8.13 | 12 | 34 – 37 |
Mean ± SE | 7.39 ± 0.49 | ||
Male with genital cone, no indication of oostegites | |||
1 | 8.35 | 12 | 31 (damaged) |
The body sizes of individual Brachylicoa lui measured during this study are presented in Table
The adult female of Brachylicoa lui sp. n. (Fig.
The new Hawaiian species differs from B. muelleri by having the ventral margin of the carapace with a row of 13 spiniform setae (nine in muelleri), antenna with 18 articles (13 in muelleri), and more setae on the first article of the mandibular palp (20–25 versus 6). Brachylicoa lui closely resembles B. indonesiana by having a mandibular palp article-1 with a cluster of more than ten simple setae, but it can be distinguished by (1) carapace having ventral margin with row of 13 spiniform setae (nine in indonesiana), (2) the maxillule biarticulated palp with total of eight sub-terminal and terminal “cleaning’ setae (five in indonesiana), (3) female cheliped basis lacking a blunt spine on the dorsal margin of the basis (one present in indonesiana), (4) pereopod-1 with distoventral margin of basis lacking a stout spiniform seta (one present in indonesiana) and merus without distodorsal stout spiniform seta (one present in indonesiana), (5) pereopod-1 with distoventral margin of basis lacking a stout spiniform setae (one present in indonesiana), and (6) the basal article of pleopod with plumose setae (without plumose setae in indonesiana). Brachylicoa lui is distinguished from B. estasiatica by the absence of an acute rostrum with serrate margins, antenna having 18 articles, and a mandible without tubercles on the outer surface. In contrast, B. estasiatica has 15 antennal articles, an acute rostrum with serrate margins, and a mandible with tubercles on the outer surface. The following key may be used to separate the species within the genus Brachylicoa.
1 | Tip of rostrum relatively long (over 1/3 length of rest of rostrum), posterior lateral margins distinctly serrate (Fig. |
B. estasiatica [South China Sea: Malaysia] |
– | Tip of rostrum small (less than 1/4 length of rest of rostrum), lateral margins of rostrum not distinctly serrate (Fig. |
2 |
2 | Rostrum not basally incised (Fig. |
B. indonesiana [Indonesia: Celebes Sea] |
– | Rostrum basally incised (Fig. |
3 |
3 | Mandibular palp, article-1 with cluster of six or fewer simple setae (Fig. |
B. muelleri [Western Indian Ocean: Tanzania] |
– | Mandibular palp, article-1 having cluster of 20–25 simple setae (Fig. |
B. lui sp. n. [North Central Pacific: O‘ahu Island] |
Tip of rostrum: A Brachylicoa estasiatica; B B. indonesiana; C B. muelleri; D B. lui sp. n. Pereopod-6: E B. indonesiana; F B. muelleri; G B. lui sp. n. Pleopod: H B. indonesiana; I B. muelleri; J B. lui sp. n. Mandible palp: K B. muelleri; L B. lui sp. n. Figures modified from [
We suspect the mucus secretions produced by the glands or mucus storage sites (see Fig.
Possibly due to being overlooked, the presence of mucus glands and tub-like domiciles has not been reported previously for the genus Brachylicoa. We suspect that upon re-examination of the other species of the genus their presence will be confirmed. Similar glandular structures are prominent within the parapseudid genera Halmyrapseudes Băcescu & Guţu, 1974 and Discapseudes Băcescu & Guţu, 1976. In these genera, mucus is used in the thin walled tube domiciles (e.g., H. bahamensis: R. Heard, per. observ.) and in the lining of the burrows (e.g., D. holthuisi: see
We further suspect that these glands are analogous, or possibly homologous, to those reported for the suspension/filter feeding members of the subfamily Kalliapseudinae. In Mesokalliapseudes macsweenyi (Drumm, 2003) and Psammokalliapseudes granulosus Silva Brum 1973, similar mucus glands are involved in the in the construction of their fragile mucus tubes (
The occurrence of two distinct cheliped forms for adult females of B. lui may indicate the presence of both primary females and hermaphroditic forms in this species. The basis of the male cheliped has a characteristic sub-acute process on its mid-dorsal margin, which is absent on that of the female. If the presence of this process is indicative of terminal development of the cheliped, it may indicate protogynic development of the male. To support this conjecture, further observations are needed to determine if the functional females (i.e. those which produce viable young) for the other three species of the genus also exhibit two different female cheliped morphotypes. The males of B. lui and those of B. muelleri and B. indonesiana are characterized by the presence of a distinctive sub-acute process on cheliped basis, while the male cheliped for B. estasiatica remains unknown (
The presence of B. lui in the Hawaiian waters represents the first record for the genus from the mid-Pacific and northern Hemisphere. The other species of this genus are known from the Southern Hemisphere in coastal waters of the Indian and western South Pacific Oceans: B. muelleri from Tanzania, western Indian Ocean (
Our observations and comparisons with other Brachylicoa species go with the caveat that ontogenetic factors may skew some taxonomic characters used in some of the earlier descriptions. For this reason, we chose the holotype and paratype series for B. lui, from specimens collected from the Naval experimental site. Many appeared to have reached terminal sizes, usually much greater than those of specimens collected from surveys of natural habitats on O‘ahu. Thus, the largest specimens from the type locality should quantitatively express the maximum development of characters for defining B. lui. In contrast, most of the specimens collected from natural habitats in Kane‘ohe Bay and Waikīkī were usually smaller and mostly damaged to varying degrees from the collection and sorting processes.
Though we did not have many terminal size adult B. lui from the from the natural habitats from O‘ahu, there appeared to be fewer hermaphrodites present than in the population occurring in the settling tank at the Naval experimental site. There is a possibility that the “unnatural” biotic environmental factors experienced by the population of B. lui within the settling tank may have been a contributing factor to the high percentage of the adults being hermaphroditic. For instance, this might have been an effect of the concentrations of pheromones released by the dense population of B. lui within the restricted confines of the settling tank habitat. Notwithstanding the role of such altered conditions or abiotic factors in inducing hermaphroditism in B. lui is beyond the scope of our study.
This research is based in part on an undergraduate thesis submitted SU to the Honors College of the University of Southern Mississippi in partial fulfilment of the requirements for the degree of Bachelor of Science in the Department of Biological Sciences. We wish to thank Ralph C. DeFelice and the late Lu Eldredge of the Bernice Bishop Museum, Honolulu, Hawai‘i, for originally making the Hawaiian material available to us for study. RWH is also gratefully acknowledges travel support through the Bishop Museum’s Edmondson Visiting Scientist Fund. William Cook kindly facilitated our access to the large series of B. lui, including the holotype, collected by the U. S. Navy on O‘ahu. Also, we wish to express our appreciation to Holly Bolick, Invertebrate Collections Manager, Bishop Museum, for her assistance in obtaining ecological and location data for some of the collection sites. Lynn Kimsey and Steve Heydon, Bohart Museum of Entomology, University of California at Davis, graciously gave the third author (RWH) access to the Hawaiian collections of the late Miller. This research was initially supported by NSF grant DEB-0529749. Lu Eldredge facilitated this financial support and graciously provided RWH living accommodations during his visit to the Bishop Museum in May 2012. We would like to thank Wilmelie Cruz-Marrero for help in drafting the study map. We are most grateful for the helpful and constructive criticism provided by the three anonymous reviews. We take full responsibility for any differing systematic or taxonomic interpretations. The open access publication of this paper was generously supported by the Museum für Naturkunde, Berlin.